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  • Articles  (201)
  • biological control
  • phosphorus
  • 2015-2019
  • 1990-1994  (201)
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  • Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition  (187)
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  • Articles  (201)
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  • 1
    ISSN: 1573-0417
    Keywords: Great Basin ; climatic variations ; productivity ; organic matter ; nitrogen ; phosphorus ; hardwater lake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Sediment cores from the shallow and deep basins of Pyramid Lake, Nevada, revealed variations in composition with depth reflecting changes in lake level, river inflow, and lake productivity. Recent sediments from the period of historical record indicate: (1) CaCO3 and organic content of sediment in the shallow basin decrease at lower lake level, (2) CaCO3 content of deep basin sediments increases when lake level decreases rapidly, and (3) the inorganic P content of sediments increases with decreasing lake volume. Variations in sediment composition also indicate several periods for which productivity in Pyramid Lake may have been elevated over the past 1000 years. Our data provide strong evidence for increased productivity during the first half of the 20th Century, although the typical pattern for cultural eutrophication was not observed. The organic content of sediments also suggests periods of increased productivity in the lake prior to the discovery and development of the region by white settlers. Indeed, a broad peak in organic fractions during the 1800's originates as an increase starting around 1600. However, periods of changing organic content of sediments also correspond to periods when inflow to the lake was probably at extremes (e.g. drought or flood) indicating that fluctuations in river inflow may be an important factor affecting sediment composition in Pyramid Lake.
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  • 2
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    Nutrient cycling in agroecosystems 37 (1994), S. 1-22 
    ISSN: 1573-0867
    Keywords: animal slurries and manures ; applications to soils ; carbon- ; nitrogen- ; phosphorus ; contamination ; crop production ; dissemination ; hazardous organics ; heavy metals ; inputs ; macro- and micronutrients ; pathogens ; sewage sludges ; survival- ; transfer- ; transport and adsorption rates in soils
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The European Community is producing annually about 300 × 106 tons of sewage sludges as well as about 150, 950,160 and 200 tons of domestic, agricultural, industrial and other wastes (street litter, dead leaves etc.). About 20–25% of the German sewage sludges, which contain in average about 3.8,1.6, 0.4, 0.6, 5.3% DM−1 N, P, K, Mg and Ca, 202, 5, 131, 349, 53, 3 and 1446 mg kg−1 DM Pb, Cd, Cr, Cu, Ni, Hg, Zn as well as ca. 37 and 5 mg kg−1 Dm polychlorinated hydrocarbons and biphenyls, are recycled annually as fertilizer. In addition environmental impacts on the arable land of Germany may derive from 76,19.2, 64.7, 33.6, 7.8 and 0.1 kg ha−1 a−1 of N, P, K, Ca, Mg and Cu added as animal manures. Besides heavy metals and hazardous organics pathogens are disseminated with organic wastes. Crop production and soil fertility generally profit from the considerable amounts of plant nutrients and carbon in sewage sludges, animal slurries and manures, but the physicochemical soil properties, the composition of microbial, faunal and plant communities as well as the metabolic processes in the soil-, rhizo- and phyllosphere are changed by organic manuring. Consequences for the soil carbon-, nitrogen-and phosphorus-cycle are discussed. Impacts of heavy metals and hazardous organics on the soil biomass and its habitat as well as on transport mechanisms and surival times of disseminated pathogens in soils are reviewed with emphasis on the German situation. A proposal for future strategies (landscape recycling) is made.
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  • 3
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    Nutrient cycling in agroecosystems 40 (1994), S. 165-173 
    ISSN: 1573-0867
    Keywords: Animal manure ; eutrophication ; ground water ; nitrogen ; phosphorus ; surface runoff
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract With the rapid growth of the poultry industry in Oklahoma, U.S.A., more litter is applied to farm land. Thus, information is required on the impact of applications on regional soil and water resources. The effect of soil and poultry litter management on nitrogen (N) and phosphorus (P) loss in runoff and subsurface flow from four 16 m2 plots (Ruston fine sandy loam, 6 to 8% slope) was investigated under natural rainfall. Plots under Bermudagrass (Cynodon dactylon) received 11 Mg litter ha−1, which amounts to contributions of approximately 410 kg N and 140 kg P ha−1 yr−1. In spring, litter was broadcast on 3 of the plots; the upper half of one and total area of the other two. One of the total-area broadcast plots was tilled to 6 cm, the other remained as no till. The fourth plot served as a control. Relative to the control, litter application increased mean concentrations of total N and total P in runoff during the 16-week study for no-till (15.4 and 5.8 mg L−1) and tilled treatments (16.7 and 6.1 mg L−1). However, values for the half-area application (5.6 and 2.0 mg L−1) were similar to the control (5.7 and 1.3 mg L−1). Interflow (subsurface lateral flow at 70 cm depth) P was not affected by litter application; however, nitrate-N concentrations increased from 0.6 (control) to 2.9 mg L−1 (no till). In all cases, 〈 2 % litter N and P was lost in runoff and interflow, maintaining acceptable water quality concentrations. Although litter increased grass yield (8518 kg ha−1) compared to the control (3501 kg ha−1), yields were not affected by litter management. An 8-fold increase in the plant available P content of surface soil indicates long-term litter management and application rates will be critical to the environmentally sound use of this nutrient resource.
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  • 4
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    Nutrient cycling in agroecosystems 37 (1994), S. 107-113 
    ISSN: 1573-0867
    Keywords: Ensete ventricosum ; fertilizer response ; nitrogen ; phosphorus ; potassium ; sulphur ; starch
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Ensete (Ensete ventricosum W. Cheesm.) is a root crop which stores starch in the root and in the lower part of the stem. It is grown in the southwest of Ethiopia and due to its drought resistance, it is of outstanding importance for the supply of food to the local population. Until now virtually nothing is known about the response of Ensete to fertilizer application. Field trials carried out on three representative soils in Ethiopia showed that Ensete biomass yields were increased significantly on all three soils by nitrogen and phosphorus application. Potassium had only marginal effect on biomass growth but favourably influenced starch production. Sulfate application had no major impact on growth and starch yield. The yield response was well related to the level of available nutrients in the soil, as determined by electroultrafiltration (EUF). Leaf analysis provided preliminary evidence that optimum levels of N, P, and K may be 3.8%, 0.3%, and 4.8%, respectively.
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  • 5
    ISSN: 1573-0867
    Keywords: interaction ; isotopic exchange ; phosphorus ; plant-availability ; selenium ; soil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Phosphate, applied at 5µg P cm−3, decreased selenite sorption by from 30–70% in three soils studied. Both maximum sorption (Xm) and the binding-energy of sorption as indicated by the binding-energy related constant (k) or the molar free energy (ΔG) of the sorption reaction derived from the Langmuir equation were considerably decreased. On the other hand, phosphate sorption was decreased by increasing concentration of selenite from 0.2µg Se cm−3 to 1.0µg Se cm−3 in the initial solution. The competitive sorption of phosphate with selenite was likely the main mechanism involved in the P-Se interactions. The competitively sorbed selenite exhibited much larger desorption in 0.01M CaCl2 solution, more readily extractable to 0.5M NaHCO3 and significantly higher isotopic exchangeability compared to that sorbed without the competing anion. Results from pot trial using ryegrass indicated that phosphate application increased more efficiently the plant-availability of applied fertilizer Se than that of indegeneous Se in soil.
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  • 6
    ISSN: 1432-0495
    Keywords: Nitrogen ; phosphorus ; Precipitation collector ; Nutrients rates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract The contribution of nitrogen and phosphorus due to precipitation constitutes the second most important route after superficial runoff. The sampling carried out during a two-year period by means of a precipitation collector allows us to determine the contribution of this route both qualitatively and quantitatively. Nitrogen is mainly supplied in an inorganic form, while phosphorus is principally supplied as orthophosphate. During the period of this study (March 1986–February 1988) it was found that in the Santillana Reservoir Watershed the level of nitrogen supplied by precipitation constitutes an average of 4.87% and the level of phosphorus constitutes 8.01%. The contribution of nitrogen varies in inverse ratio to precipitation and the contribution of phosphorus varies in direct ratio.
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  • 7
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    European journal of plant pathology 100 (1994), S. 137-156 
    ISSN: 1573-8469
    Keywords: biological control ; mycoparasite ; potato black scurf ; Rhizoctonia solani ; sclerotia ; soil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Verticillium biguttatum cannot utilise cellulose or nitrate-nitrogen and it requires biotin for growth, yet it grew and sporulated abundantly onRhizoctonia solani on cellulose, obtaining at least organic carbon, nitrogen and biotin fromR. solani. Videomicroscopy of inter-hyphal interactions on films of water agar showed thatV. biguttatum behaved as a biotrophic mycoparasite. From germinating spores, it penetrated the hyphae ofR. solani and formed haustorium-like branches without killing the host cells, and the haustoria supported an external mycelial network of the mycoparasite. Later the mycoparasite sporulated, and the infected host cells died. On cellulosic substrataV. biguttatum did not reduce the growth ofR. solani, and often enhanced the rate of cellulose degradation. However,V. biguttatum drastically reduced the production of sclerotia byR. solani, often completely suppressing sclerotium production when the mycoparasite infected only a localized region of the host colony. This is ascribed to the creation of a nutrient sink by the parasite, consistent with biotrophy. On plates of cellulose agar the suppression of sclerotia was not confined to parasitized colonies but extended to adjacent colonies ofR. solani that had successfully anastomosed with the parasitized colony. There was no effect on adjacent vegetatively incompatible colonies, where attempted anastomoses caused cytoplasmic death. In comparable experiments the necrotrophic mycoparasiteGliocladium roseum had no long-distance effect on sclerotium production byR. solani. Suppression of sclerotium production may explain the reported success ofV. biguttatum in biocontrol of black scurf of potato in experimental field conditions.
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  • 8
    ISSN: 1573-8469
    Keywords: biological control ; antibiotics ; Tn5 mutagenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Pseudomonas fluorescens strain CHA0 is an effective biocontrol agent of various soilborne pathogens. It controls damping-off or root rot caused byPythium ultimum on cucumber, wheat and cress. Strain CHA0 synthesizes several antibiotic metabolites such as hydrogen cyanide, 2,4-diacetylphloroglucinol, and pyoluteorin. The role of pyoluteorin in the suppression of damping-off was investigated. Two Tn5 mutants (CHA660 and CHA661) of strain CHA0 were isolated which had lost the capacity to produce pyoluteorin but still produced 2,4-diacteylphloroglucinol and HCN. These mutants still inhibitedP. ultimum on malt agar (which favours the production of 2,4-diacetylphloroglucinol) but had partially lost the ability to inhibit this pathogen on King's B agar (which favours the production of pyoluteorin). The two pyoluteorin-negative mutants showed a reduced capacity to suppress damping-off of cress caused byP. ultimum but were as effective in the protection of cucumber against this pathogen as the wild-type strain. These results indicate that, depending on the plant, pyoluteorin production plays a role in the suppression of damping-off by strain CHA0 without being a major mechanism in disease suppression. We suggest that the contribution of pyoluteorin to the biocontrol activity of strain CHA0 is determined by the quantity of this antibiotic produced in the rhizosphere, which might depend on the root exudates of the host plant.
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  • 9
    ISSN: 1573-5036
    Keywords: nitrogen ; phosphorus ; revegetation ; silica ; succession ; shrubland
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Fire is the principal means of stand renewal in big sagebrush-steppe communities of western North America. Plant growth following fire may be influenced by heat-induced changes in the nutrient status of the soil. Moreover, post-wildfire pioneer plant species may alter soil properties, and thereby, impact subsequent plant recruitment. Our study compared the growth and elemental content of big sagebrush (Artemisia tridentata), squirreltail (Elymus elymoides), cheatgrass (Bromus tectorum), and Indian ricegrass (Achnatherum hymenoides), grown under greenhouse conditions in post-wildfire and similar unburned soil. We also examined soil attributes following plant growth. Cheatgrass and squirreltail, grown in post-wildfire soil, had significantly (p≤0.05) greater aboveground mass than plants grown in unburned soil. As compared with unburned soil, post-wildfire soil engendered the following significant (p≤0.05) differences in leaf elemental content: 1) big sagebrush had higher levels of P and lower levels of Mn; 2) squirreltail accumulated more P and N; and 3) all grass species had higher SiO2 content. Following harvest of plants, post-wildfire soil generally contained significantly (p≤0.05) more KCl-extractable ortho-P, NH inf4 + , and SO 4 − , than unburned soil. Plant growth in both burned and unburned soils fostered a significant (p≤0.05) increase in the bicarbonate-extractable pool of P as compared with unplanted controls. Soil Kjeldahl-N was significantly (p≤0.05) greater after plant growth in burned treatments as compared with the control. This study demonstrates that post-wildfire soil can have a stimulatory effect on plant growth for some species. Squirreltail deserves consideration as a post-wildfire revegetation species. Furthermore, pioneer plant growth following wildfires can attenuate soil properties and therefore influence plant succession.
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  • 10
    ISSN: 1573-5036
    Keywords: phosphorus ; root disease ; soil acidity ; subterranean clover ; yield decline
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Experimental sites were established at two locations in north-eastern Victoria to define factors limiting the establishment and growth of Trifolium subterranean L. (subterranean clover). Liming the soil, seed inoculation and fungicide application were used in renovating subterranean clover pasture on two acidic soils (Longwood: brown/grey sandy loam DY 3.14 and Seymour: grey brown light clay DY 3.22, Northcote classification) with mean annual rainfall of 650 mm and 600 mm respectively. Soil acidity, low available soil phosphorus and plant disease were identified as factors limiting clover yield on these soils. Significant yield responses to lime (35–140%) were obtained with subterranean clover at both sites, with corresponding decreases in Al in the 0–10 cm soil horizon. Liming the soil, when combined with seed inoculation, increased the number and effectiveness of root nodules at both sites. Soil P available for plant growth was low at both sites (6.1 and 8.4 μg g−1) resulting in sub-optimal P concentrations in the clover herbage (45 mmol kg−1 at Longwood). Levels of root disease were low but Aphanomyces euteiches and Phytophthora clandestina (causal agents of lateral and tap root rot) were detected frequently on roots. Application of fungicide resulted in higher dry matter yields (p=0.05) at both sites. An assessment of the relative contributions of these limiting factors and the benefits to be obtained from better management would provide a clearer picture of the profitability and sustainability of this farming system.
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  • 11
    ISSN: 1573-5036
    Keywords: antibiosis ; bacterization ; biological control ; chitinase ; sheath blight
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Bacterial antagonists of both fluorescent and nonfluorescent groups were screened for in-vitro inhibition of the rice sheath blight (ShB) fungus Rhizoctonai solani Kuhn and chitinase production in the laboratory. Twelve percent of the total 1,757 strains screened inhibited R. solani while 31% of the total 1,366 strains tested were positive for chitinase activity. The efficient strains were then evaluated in the field for ShB suppression. Two strains from each of the three seed-bed experiments were chosen for the field test in a hot-spot location. Additional treatments were a Bacillus and validamycin, the fungicide. There was no correlation between chitinase activity in the antagonists and ShB suppression in the seed-bed or field plots. Two most efficient Pseudomonas putida and P. fluorescens strains afforded 68 and 52% ShB suppression while validamycin afforded 27% disease control.
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  • 12
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    Plant and soil 159 (1994), S. 213-218 
    ISSN: 1573-5036
    Keywords: concentration gradient ; diffusion ; phosphorus ; rhizosphere ; soil moisture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract To study the influence of soil moisture on phosphorus (P) depletion in the rhizosphere, maize (Zea mays cv. Trak) was pre-grown in vermiculite filled-PVC tubes for 9 days and then the plants with the tubes were transplanted into soil columns maintained at two soil moisture levels (θ) of 0.14 and 0.20 cm3 cm−3 for 10 days. The soil columns were separated at 1 cm depth by a nylon screen of 53 μm inner mesh size, into 1 cm soil layer above and 3 cm soil column below screen. A root mat developed over the screen, but root hairs only could penetrate it. Regardless of the soil moisture level in the columns, and adequate and equal water and nutrients supply was maintained via wicks from an external nutrient solution to the plant roots in vermiculite. After 10 days, the soil columns were separated from the root mats, quickly frozen in liquid nitrogen and sliced into thin layers (0.2mm) using a refrigerated microtome to give soil samples at defined distances from the root mats for analyses. Lower soil moisture (θ=0.14) resulted in narrower and steeper depletion profile of 0.5 M NaHCO3 extractable P (NaHCO3-Pi) as compared to higher soil moisture (θ=0.20). Depletion of P in soil solution in the immediate vicinity of root mats did not differ much but the extension of the depletion zones was 0.10 cm at θ=0.14 and 0.20 cm at θ=0.20. The depletion up to 0.05cm with θ=0.14 and up to 0.07 cm with θ=0.20 was uniform, and may be attributed to the depletion in the root hair zone. Beyond the root hair zones, the theory of diffusion and mass flow was able to explain the observed differences in shape and extent of the P depletion profiles at the two soil moisture levels.
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  • 13
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    Plant and soil 165 (1994), S. 81-88 
    ISSN: 1573-5036
    Keywords: carbohydrates ; ectomycorrhizae ; elevated CO2 ; phosphorus ; Pinus taeda L. ; Pisolithus tinctorius (Pers.) Coker & Couch
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Interactive effects of elevated atmospheric CO2 and phosphorus supply on mycorrhizal colonization rates were investigated using loblolly pine (Pinus taeda L.) seedlings from Florida and coastal North Carolina. Seedlings from both populations were grown in greenhouses maintained at either 35.5 Pa or 71.0 Pa CO2. In both CO2 treatments, seedlings were grown in a full factorial experiment with or without mycorrhizal inoculum and with an adequate or a limiting supply of phosphorus. Seedlings were harvested 60, 90 and 120 days after emergence and at each harvest root subsamples were examined to determine the percent of fine roots that were mycorrhizal. Additionally, root carbohydrate and nutrient levels were measured at each harvest. Root starch, sugar and total non-structural carbohydrate (TNC) concentrations were increased by growth in elevated CO2 and decreased by mycorrhizal colonization. Phosphorus stress decreased root starch concentrations, increased root sugar concentrations and did not significantly affect TNC concentrations. However, despite significant effects on root carbohydrate levels, there were generally no significant treatment effects on mycorrhizal colonization. Additionally, at all harvests, root starch and sugar concentrations were not correlated with percent of fine roots that were mycorrhizal. These results suggest that although elevated CO2 may significantly increase root carbohydrate levels, the increases may not affect the percent of fine roots that are mycorrhizal.
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  • 14
    ISSN: 1573-5036
    Keywords: blue grama ; Bouteloua gracilis ; C4 grass ; CO2 enrichment ; mycorrhizae ; nitrogen ; phosphorus ; VAM ; water relations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In order to better elucidate fixed-C partitioning, nutrient acquisition and water relations of prairie grasses under elevated [CO2], we grew the C4 grass Bouteloua gracilis (H.B.K.) lag ex Steud. from seed in soil-packed, column-lysimeters in two growth chambers maintained at current ambient [CO2] (350 μL L−1) and twice enriched [CO2] (700 μL L−1). Once established, plants were deficit irrigated; growth chamber conditions were maintained at day/night temperatures of 25/16°C, relative humidities of 35%/90% and a 14-hour photoperiod to simulate summer conditions on the shortgrass steppe in eastern Colorado. After 11 weeks of growth, plants grown under CO2 enrichment had produced 35% and 65% greater total and root biomass, respectively, and had twice the level of vesicular-arbuscular mycorrhizal (VAM) infection (19.8% versus 10.8%) as plants grown under current ambient [CO2]. The CO2-enriched plants also exhibited greater leaf water potentials and higher plant water use efficiencies. Plant N uptake was reduced by CO2 enrichment, while P uptake appeared little influenced by CO2 regime. Under the conditions of the experiment, CO2 enrichment increased root biomass and VAM infection via stimulated growth and adjustments in C partitioning below-ground.
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  • 15
    ISSN: 1573-5036
    Keywords: efficiency ; Glomus intraradices ; phosphorus ; root hair ; rye ; Secale cereale L. ; VA mycorrhiza
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Plant growth and phosphorus (P) uptake of two selections of rye (Secale cereale L.) differing in length of root hairs, in response to mycorrhizal infection were investigated. Rye plants with short root hairs (SRH) had a greater length of root infected by Glomus intraradices (up to 32 m pot−1) than those with long root hairs (LRH) (up to 10 m pot−1). Application of P decreased the percentage of root length infected in both selections. In low-P soil, mycorrhizal infection increased shoot and root P concentration, especially in LRH plants. Generally, LRH had higher shoot dry weight than SRH plants. P uptake was increased both by LRH and by mycorrhizal infection. Differences in specific P uptake and P utilization efficiency between SRH and LRH plants were observed in non-mycorrhizal plants. With low P supply, P utilization efficiency (dry matter yield per unit of P taken up) of LRH plants increased with time. However, mycorrhizal infection reduced P utilization efficiency, particularly of SRH plants. SRH plants, which were agronomically less efficient (i.e. low dry matter yield at low P supply) were more responsive to either mycorrhizal infection or P addition than the LRH plants. No interaction was observed between mycorrhizal infection and root hair length.
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  • 16
    ISSN: 1573-5036
    Keywords: alginate ; biological control ; Cucumis sativus ; Lycopersicon esculentum ; Meloidogyne incognita ; microbial ecology ; nematode eggs ; soil microbiology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A method was developed for utilizing alginate films to deliver inoculum into soil and evaluate microbial antagonistic activity against nematode eggs. Eggs of Meloidogyne incognita were harvested from galled tomato roots (Lycopersicon esculentum), surface disinfested, suspended in 2% (w/v) aqueous sodium alginate, and applied to 2.5 × 5.0 cm polyvinyl chloride coated fiberglass screens (1.5 mm2 mesh size) at a uniform thickness of 0.5 mm. The alginate solution was gelled by dipping in 0.25 M CaCl2. Films containing eggs were observed in vitro and egg development was evaluated. The number of immature eggs and eggs with first stage juveniles declined linearly over time while the number of empty eggs shells, and hatched juveniles increased over time, indicating that the alginate gel did not inhibit development and motility of M. incognita juveniles. In a greenhouse experiment using cucumber (Cucumis sativus) the number of galls g-1 root was correlated with the number of eggs in alginate films placed in each pot at planting. Films containing M. incognita eggs were buried in field soil containing organic amendments, incubated, removed from soil, rinsed with water, and observed. The number of immature eggs in grids from soil amended with chitin or flax seed meal were lower than in untreated soil; percent parasitized eggs was also greater in films from amended soil than from untreated soil.
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  • 17
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    Plant and soil 160 (1994), S. 193-199 
    ISSN: 1573-5036
    Keywords: gaps ; ion uptake ; nitrogen ; nutrient acquisition ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Tree seedlings that colonize large treefall gaps are generally shade-intolerant species with high potential relative growth rates. Nutrient availability may be significantly elevated in disturbance-induced gaps, however, little is known about the role of differences in nutrient uptake capacities of different species in structuring the community response to gap openings in eastern North American deciduous forests. Seven tree species were grown from seed under both a high and a low nutrient regime, and uptake kinetics of phosphate, ammonium, and nitrate were studied. Yellow birch, a species with intermediate shade tolerance and relative growth rate, had the highest maximum rates of uptake of all ions, while tulip tree, a gap-colonizing species with high relative growth rate, had the lowest rate of phosphate uptake and intermediate rates of ammonium and nitrate uptake. Beech and hickory, which have low relative growth rates and are not gap-colonizing species, had intermediate levels of nutrient uptake. There was no evidence that species with the highest maximum uptake rates measured at high supply concentrations had relatively low uptake at low nutrient supply concentrations. Although birch increased phosphate absorption capacity when grown under a low nutrient regime, this pattern did not hold for nitrate or ammonium uptake, and other species showed no change in nutrient uptake capacity according to nutrient growth regime. Clearly, factors other than nutrient absorption capacity, such as nutrient use efficiency or allocation to root vs. shoot biomass, underlie differences in species' capacities to colonize and maintain a high relative growth rate in canopy gaps.
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  • 18
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    Plant and soil 165 (1994), S. 161-169 
    ISSN: 1573-5036
    Keywords: carbon cost ; phosphorus ; Phaseolus vulgaris ; root architecture ; root growth ; root simulation model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Root architecture is an important component of nutrient uptake and may be sensitive to carbon allocational changes brought about by rising CO2. We describe a deformable geometric model of root growth, SimRoot, for the dynamic morphological and physiological simulation of root architectures. Using SimRoot, and measurements of root biomass deposition, respiration and exudation, carbon/phosphorus budgets were developed for three contrasting root architectures. Carbon allocation patterns and phosphorus acquisition efficiencies were estimated for Phaseolus vulgaris seedlings with either a dichotomous, herringbone, or empirically determined bean root architecture. Carbon allocation to biomass, respiration, and exudation varied significantly among architectures. Root systems also varied in the relationship between C expenditure and P acquisition, providing evidence for the importance of architecture in nutrient acquisition efficiency.
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  • 19
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    Plant and soil 166 (1994), S. 21-30 
    ISSN: 1573-5036
    Keywords: aluminium ; growth period ; phosphorus ; plant age ; root length ; root width ; solution culture ; techniques ; Triticum aestivum ; variation ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of growth period (time between transplanting and harvesting), plant age at which aluminium (Al) was added to solution, changes in Al concentration, and solution culture techniques (monitoring and adjusting solution Al concentrations thrice weekly or weekly replacement of the solutions) were investigated using a low ionic strength (2.7×10−3 M) solution culture technique. The wheat (Triticum aestivum L.) cultivars Waalt (Al-tolerant) and Warigal (Al-sensitive), or the near isogenic lines bred from these cultivars (RR for the Al-tolerant line and SS for the Al-sensitive line) were grown. In all experiments and treatments, Al additions were required to maintain the nominal concentration. The decline in solution Al concentrations was partially attributed to formation of an Al-hydroxy-phosphate precipitate with an Al:P molar ratio of 2.8 to 4.0. Increasing the growth period from 14 to 28 days increased Al sensitivity in Warigal but not in Waalt. When plants were exposed to Al for the same time, increasing the age of the plants that Al was added to solution decreased sensitivity to Al. Differential Al tolerance between the two lines was evident when solutions were monitored thrice weekly or replaced weekly. However, the Al concentration required to reduce relative yield by a given amount when the solutions were replaced weekly was about twice that when the solutions were monitored. With a constant growth period of 28 days, increasing solution Al concentrations for 3 or more days resulted in decreased yields at harvest. The exact effect depended on the cultivar, plant part (tops or roots), when solution Al concentrations were increased and the duration of the increase. For example, increasing Al concentrations from 5 μM to 20 μM for 10 days reduced yield in the RR line by approximately 50% in the tops and 30% in the roots beyond the effect of 5 M but had no effect in the SS line due to yields already being low at 5 μM. Adding 10 μM Al to solution for 6 days at the beginning of the experiment reduced yield by 25% in the RR line and 50% in the SS line. In contrast, adding 10 μM Al for 6 days in the middle of the growth cycle had no effect on the RR line but reduced yield by approximately 25% in the SS line. These results show that growth period, the age of the plants at which Al is added and the technique used (monitored or weekly replacement) all need to be considered when comparing results from different experiments. These results also show that the Al concentrations in solution need to be regularly monitored in long term experiments.
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  • 20
    ISSN: 1573-5036
    Keywords: organic agriculture ; phosphorus ; rock phosphate ; VA-mycorrhizas ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Levels of colonisation by vesicular-arbuscular (VA)-mycorrhizal fungi were compared between adjacent farms, one operated in a conventional manner and the other run according to organic farming principles. Wheat grown on the organic farm was found to have VA-mycorrhizal colonisation levels consistently 2 to 3 times higher than wheat on the conventional farm. Glasshouse and field trials indicated that the lower colonisation levels on the conventional farm were due to continual use of fertiliser containing soluble phosphorus (P). The fertiliser appeared to have an immediate negative effect on the rate of colonisation, and also appeared to have a long term negative effect through maintaining higher levels of soluble P in the soil, and by decreasing inoculum levels. Use of the relatively insoluble reactive rock phosphate fertiliser on the organic farm did not decrease levels of VA-mycorrhizas. Colonisation levels did not vary between wheat varieties, and herbicides and seed dressings were also not found to be having any significant effect on levels of colonisation.
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  • 21
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    Plant and soil 163 (1994), S. 77-83 
    ISSN: 1573-5036
    Keywords: actinomycetes ; biological control ; Brassica rapa ; Daucus carota ; PGPR ; rhizosphere
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Root-colonization ability of Streptomyces griseoviridis was tested on turnip rape (Brassica rapa subsp. oleifera) and carrot (Daucus carota) by the plate test and the sand-tube method. In the plate test, colonized root length of total root length was highly significantly greater for turnip rape roots (72%) from those for carrot roots (1%). In the sand-tube method, root-colonization ability was examined in nonsterile soil, and no water was added after sowing. Seeds were treated with spores of S. griseoviridis or the biofungicide Mycostop. Roots were cut into 2-cm segments, and the root segments and the rhizosphere soil were studied separately. Root-colonization frequencies and population densities of the microbe in the rhizosphere soil indicated that S. griseoviridis successfully colonized turnip rape but weakly colonized carrot. Root-colonization of turnip rape is accounted for as proliferation of S. griseoviridis in the rhizosphere of turnip rape seedlings and is not due to the movement of microbe through the rhizosphere by water infiltration.
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  • 22
    ISSN: 1573-5095
    Keywords: foliage ; grafting ; nitrogen ; phosphorus ; Pinus caribaea ; rootstock ; scion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Both scion and rootstock clones significantly influenced scion elongation and concentrations of nitrogen and phosphorus in the scion foliage. Scion clone was the more important determinant. Scion clone × rootstock clone interactions were not significant. The ability of a clone to elongate as a scion was not correlated with its capacity to promote or retard scion elongation when used as a rootstock. Genetic differences in foliar nutrient concentrations appeared to reflect levels of nutrient demand, rather than the ability of roots to absorb nutrients. Nutrient demand of the rootstock can also explain negative correlations between nitrogen levels in rootstock clones and levels of both nitrogen and phosphorus in the scions. There was no significant relationship between scion elongation and foliar nitrogen concentrations of either rootstock or scion. The weak relationship between scion elongation and concentration of phosphorus in the rootstock apparently resulted from tissue dilution.
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  • 23
    ISSN: 1573-515X
    Keywords: carbonate sediments ; phosphate adsorption ; phosphorus ; phosphorus limitation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract We determined phosphate uptake by calcareous sediments at two locations within a shallow lagoon in Bermuda that varied in trophic status, with one site being mesotrophic and the other being more eutrophic. Phosphate adsorption over a six hour period was significantly faster in sediments from the mesotrophic site. Uptake at both sites was significantly less than that reported for a similar experiment on calcareous sediments in an oligotrophic lagoon in the Bahamas. The difference in phosphorus adsorption between our sites did not appear to be related to sediment characteristics often cited as important, such as differences in surface area (as inferred from grain size distributions), total organic matter content, or iron content. However, the sediment total phosphorus contents were inversely related to phosphorus uptake at our sites in Bermuda, and at the previously studied Bahamas site. We hypothesize that phosphate uptake in these calcareous sediments is a multi-step process, as previously described for fluvial sediments or pure calcium carbonate solids, with rapid initial surface chemisorption followed by a slower incorporation into the carbonate solid-phase matrix. Accordingly, sediments already richer in solid phase phosphorus take up additional phosphate more slowly since the slower incorporation of surface-adsorbed phosphate into the carbonate matrix limits the rate of renewal of surface-reactive adsorption sites. Although carbonate sediments are a sink for phosphate, and thereby reduce the availability of phosphorus for benthic macrophytes and phytoplankton in the shallow overlying water, phosphate uptake by these sediments appears to decrease along a gradient from oligotrophic to eutrophic sites. If our result is general, it implies a positive feedback in phosphorus availability, with a proportionately greater percentage of phosphorus loading being biologically available longer as phosphorus loading increases. This pattern is supported by the significantly higher tissue phosphorus content of the seagrass,Thalassia testudinum, collected from the eutrophic inner bay site. Over time, this effect may tend to cause a shift from phosphorus to nitrogen limitation in some calcareous marine environments.
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  • 24
    ISSN: 1572-9680
    Keywords: Argania spinosa ; micro-elements ; nitrogen ; phosphorus ; V.A. mycorrhization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé L'influence de la mycorhization V.A. sur la nutrition minérale de 2 clones d'Arganier (Argania spinosa) a été étudiée sur des plantules micropropagées in vitro poussant en conditions contrôlées. L'inoculation (qui augmentait la production de matière sèche d'un facteur 4,5) accroit également la teneur des plantes en phosphore, notamment dans les feuilles, et les plantes mycorhizées mobilisent 15 fois plus de phosphore que les plantes non inoculées. La teneur en azote est légèrement plus faible chez les plantes mycorhizées mais au total ces dernières exportent 3 fois plus d'azote. L'absorption des micro-éléments est aussi affectée par l'inoculation, qui accroit les teneurs des plantes en Fe, Zn et Cu. La nutrition minérale des deux clones étudiés semble affectée par le rapport racines/parties aériennes et d'autres caractéristiques génétiques, comme l'efficacité de translocation du fer. Ces résultats nous permettent de comprendre en quoi son système racinaire profond et mycorhizé permet à l'Arganier non seulement de pousser dans des zones arides aux sols pauvres, mais aussi d'améliorer la fertilité des couches supérieures du sol par l'effet litière.
    Notes: Abstract The influence of V.A. mycorrhization on mineral nutrition of 2 clones ofArgania spinosa was studied with in-vitro micropropagated plantlets grown in confined medium under controlled conditions. Inoculation, which increased dry matter production by a factor of 4.5, also increased P concentration in the plant, especially in the leaves, and the mycorrhizal plants mobilized 15 times more P than control plants. N concentration was slightly lower in mycorrhizal plants, but total N content was 3 times higher. Uptake of micro elements was also affected, inoculation increasing plant Fe, Zn and Cu content. Mineral nutrition in the test clones seemed affected by root/shoot ratio and other genetically-related characteristics, such as Fe translocation efficiency. These results help us to understand how its deep mycorrhizal root system might allowArgania spinosa not only to grow in infertile arid areas but also to improve top-soil fertility by a litter effect.
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  • 25
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    Plant and soil 159 (1994), S. 89-102 
    ISSN: 1573-5036
    Keywords: copper ; ectomycorrhizas ; hyphal uptake ; phosphorus ; vesicular-arbuscular mycorrhizas ; zinc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The role of mycorrhizal fungi in acquisition of mineral nutrients by host plants is examined for three groups of mycorrhizas. These are; the ectomycorrhizas (ECM), the ericoid mycorrhizas (EM), and the vesicular-arbuscular mycorrhizas (VAM). Mycorrhizal infection may affect the mineral nutrition of the host plant directly by enhancing plant growth through nutrient acquisition by the fungus, or indirectly by modifying transpiration rates and the composition of rhizosphere microflora. A capacity for the external hyphae to take up and deliver nutrients to the plant has been demonstrated for the following nutrients and mycorrhizas; P (VAM, EM, ECM), NH4 + (VAM, EM, ECM), NO3 - (ECM), K (VAM, ECM), Ca (VAM, EM), SO4 2- (VAM), Cu (VAM), Zn (VAM) and Fe (EM). In experimental chambers, the external hyphae of VAM can deliver up to 80% of plant P, 25% of plant N, 10% of plant K, 25% of plant Zn and 60% of plant Cu. Knowledge of the role of mycorrhiza in the uptake of nutrients other than P and N is limited because definitive studies are few, especially for the ECM. Although further quantification is required, it is feasible that the external hyphae may provide a significant delivery system for N, K, Cu and Zn in addition to P in many soils. Proposals that ECM and VAM fungi contribute substantially to the Mg, B and Fe nutrition of the host plant have not been substantiated. ECM and EM fungi produce ectoenzymes which provide host plants with the potential to access organic N and P forms that are normally unavailable to VAM fungi or to non mycorrhizal roots. The relative contribution of these nutrient sources requires quantification in the field. Further basic research, including the quantification of nutrient uptake and transport by fungal hyphae in soil and regulation at the fungal-plant interface, is essential to support the selection and utilization of mycorrhizal fungi on a commercial scale.
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  • 26
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    Plant and soil 162 (1994), S. 89-97 
    ISSN: 1573-5036
    Keywords: desorption ; phosphorus ; rice ; variable-charge mineral
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Experiments were conducted to study the desorption characteristics and plant-availability of phosphate sorbed by some important variable-charge minerals including kaolinite, goethite and amorphous Al oxide. Phosphate desorption from the complexes of goethite-P, kaolinite-P and Al oxide-P by equilibration with 0.02M KCl, resin or some commonly used chemical extractants was slow compared to desorption from a permanent-charge mineral (montmorillonite). However, rice plants were not observed under P deficiency in a pot trial with a phosphate-mineral complex as the only P source for both the permanent-charge mineral and the variable-charge minerals at either 50% or 100% sorption saturation with the exception of goethite-P at 50% saturation. In the exceptional goethite-P treatment, plant P concentration (1.0 g kg−1) was on the threshold of P deficiency. From 15% to 31% of the applied P was recovered by the plants within a growing period of three months, depending on sorption saturation and mineral type. Both the dry matter yield and P uptake decreased with decreasing sorption saturation for all the tested complexes except for Al oxide-P100 (100% saturation). In the case of Al oxide-P100, Al toxicity may have occurred, for poor root growth and high Al concentration in the plants were observed. The effect of sorption saturation on the yield and P uptake of plant was obvious for kaolinite and goethite but not very significant for montmorillonite. Based on the recovery of applied P, the plant-availability decreased in the following order: kaolinite-P100 〉 goethite-P100 〉 Al oxide-P50 〉 montmorillonite-P100 〉 montmorillonite-P50 〉 kaolinite-P50 〉 goethite-P50. Fractionation of the sorbed P before and after plant uptake showed that most of the P uptake originated from the resin-exchangeable P fraction in montmorillonite-P complex, but came mainly from NaOH-extractable fractions in goethite-P complex, whereas all the resin-P, NaHCO3-P and NaOH-P fractions in kaolinite- and amorphous Al oxide-P complex made a contribution to P uptake.
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  • 27
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    Euphytica 77 (1994), S. 243-250 
    ISSN: 1573-5060
    Keywords: Acid soils ; phosphorus ; selection ; Trifolium repens ; white clover
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A total of 490 white clover genotypes were grown in competition withAgrostis tenuis and repeatedly defoliated, in a glasshouse trial. The percentage change in shoot yield from the first to the last harvest (harvest 6) was negatively correlated with the soil-P level from which ecotypes were collected. High- and low-yielding genotypes were selected from this study and compared in a field trial on a low-P soil (12 mg Olsen P/kg soil), in a grazed mixed species sward. Over the first year there was no significant difference in spread into the sward, and over three years no significant difference in persistence. Selection in glasshouses for yield is unlikely to improve edaphic stress tolerance in the field. In a field study in New Zealand, comparison of six ecotype populations showed that after one year the highest-spreading population had been collected from a low-P soil while the lowest spreading population came from a high-P soil, although the correlation between spread and soi-P from which ecotypes were collected was not significant (r=−0.67 p〉0.05). However, in another field trial in England it was shown that populations collected from low-P soils not only outyielded those, collected from high-P soils but that they also responded less to added P. It was concluded that populations collected from low-P soils will be a useful source of germplasm to identify genotypes adapted to low-P soils. Successful identification of such genotypes is most likely to be made in the field rather than in controlled more artificial environments.
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  • 28
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    European journal of plant pathology 100 (1994), S. 279-282 
    ISSN: 1573-8469
    Keywords: ascospores ; biological control ; chinese aster ; germination ; heat resistance ; seed coating ; survival ; tomato
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Spores of the biocontrol agentTalaromyces flavus were recovered from coating material of chinese aster and tomato seeds in which they were incorporated 17 years before. The seeds had been stored at room temperature. About 20% of the ascospores had retained their heat resistance and survived treatment in aqueous suspension at 60°C for 30 min. None of the chinese aster seeds and 90% of the tomato seeds germinated after the storage period. Presence ofT. flavus during storage had not affected germinability of the seeds.
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  • 29
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    European journal of plant pathology 100 (1994), S. 315-336 
    ISSN: 1573-8469
    Keywords: biological control ; Botrytis cinerea ; grey mould ; sorulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Sixty isolates of saprophytic microorganisms were screened for their ability to reduce the severity of grey mould (Botrytis cinerea) infection and sporulation. Isolates of the bacteriaXanthomonas maltophilia, Bacillus pumilus, Lactobacillus sp., andPseudomonas sp. and the fungusGliocladium catenulatum reduced germination of conidia of the pathogen and controlled disease on bean and tomato plants. Their activity under growth room conditions was good, consistent, and similar to the activity of the known biocontrol agent,Trichoderma harzianum T39 (non-formulated). Although the tested isolates may for nutrients with the germinating conidia ofB. cinerea, resistance induced in the host by live or dead cells were also found to be involved. Inhibitory compounds were not detected on treated leaves. Sporulation ofB. cinerea after its establishment on leaves was also reduced by the above mentioned isolates and byPenicillium sp.,Arthrinium montagnei, Ar. phaeospermum, Sesquicillium candelabrum, Chaetomium globosum, Alternaria alternata, Ulocladium atrum, andT. viride. These sporulation-inhibiting fungi did not reduce the infection of leaves byB. cinerea. Most of these selected fungi and bacteria were capable of reducing lesion expansion.
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  • 30
    ISSN: 1573-8469
    Keywords: Trichoderma spp. ; biological control ; increased growth response ; PGPR ; damping-off
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Trichoderma harzianum was applied to cucumber and pepper seedlings as a peat-bran preparation incorporated into the propagative mixture in a commercial production nursery. On marketing day (after 18 and 30 days for cucumber and pepper, respectively), significant increases of 23.8% and 17.2% in seedling height, 96.1% and 50% in leaf area, and 24.7% and 28.6% in plant dry weight were observed in cucumber and pepper seedlings, respectively, as compared to their non-treated counterparts.Trichoderma-treated seedlings were much more developed and vigorous and had higher chlorophyll contents. No significant differences were found in N, P or K content between treatments. Cucumber seedlings were then transplanted to a commercial greenhouse and analyzed over two successive growth cycles following soil fumigation with methyl bromide (500 kg/ha). Results revealed theTrichoderma-treated plants to be more resistant to damping-off disease. During the first cycle, immediately after soil fumigation, no damping-off was observed with either treatment, except in border beds where 4% of the non-treated plants died, as compared to no damping-off in theTrichoderma-treated plants. During the second growing cycle however, significant reductions in damping-off of 67% and 52% were obtained in middle and border beds, respectively, as compared to the non-treated controls.
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  • 31
    ISSN: 1573-8248
    Keywords: predatory soil mite ; biological control ; glasshouse ; development rate ; fecundity ; longevity ; rearing techniques
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé Différents aspects de la biologied'Hypoaspis miles sont examinés: vitesse de développement de l'oeuf à l'adulte à différentes températures, fécondité, longévité et voracité sur les sciarides. Avec une augmentation de la température, la durée du développement passe de 33,7 jours à 15°C à 9,2 jours à 28°C. La température minimale qui permet le développement complet deH. miles est située entre 10 et 12°C. Quand il est nourri d'"itAcarus siro, H. miles pond 2 à 3 oeufs par jour et seuls les oeufs non fécondés donnent des mâles. Les adultes deH. miles (âgés de 0 à 1 jour) survivent pendant 24±1,4 jours sans nourriture et si elles sont nourries pendant 6 jours puis privées de nourriture, les femelles vivent 65,4±2,6 jours, ce qui est significativement plus long que les mâles (45,2±3 jours). Avec de la nourriture, 60% des mâles et des femelles vivent pendant 142 jours. Toutes les larves de sciarides sont attaquées parH. miles, mais le nombre de proies consommées dépend de la taille des larves. La prédation des oeufs est négligeable et les pupes ne sont pas attaquées. Dans des études sur la productivité deH. miles en élevage (nourri deA. siro), la durée nécessaire aux acariens pour atteindre une densité de 45–65 000/1 est de 76 et 23 jours à 15°C et 28°C respectivement.
    Notes: Abstract The following aspects ofHypoaspis miles' biology were investigated; development rate of egg to adult at different temperatures, fecundity, longevity and rate of predation on sciarids. With an increase in temperature the time taken for development decreased from 33.7 days at 15°C to 9.2 days at 28°C. The threshold temperature forH. miles to complete its life cycle was between 10° and 12°C. When fed onAcarus siro, H. miles laid 2–3 eggs a day and unfertilized eggs only developed into males. Adults ofH. miles (0–1 day old) survived for 24.0±1.4 days without food and if fed for 6 days and then starved, females lived for 65.4±2.6 days which was significantly longer than males (45.2±3.0 days). With food, 60% of males and females survived for 142 days. All larval instars of sciarids were attacked byH. miles although the numbers consumed were dependent on the size of the larvae. Egg predation was negligible and pupae were not attacked. In productivity studies ofH. miles in culture (fed onA. siro), the time taken for the mites to reach a density of 45–65,000/litre ranged from 76 to 23 days at 15° and 28°C respectively.
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  • 32
    ISSN: 1573-8248
    Keywords: Abax parallelepipedus ; biological control ; mass breeding ; soil capsule ; growth rate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé Des travaux précédents ont montré qu'Abax parallelepipedus Piller & Mitterpacher est un prédateur de limaces sur le terrain et peut être employé efficacement pour leur contrôle dans les tunnels en polyéthylène. Pour que la lutte biologique soit réalisable, ce carabe doit aussi pouvoir être produit massivement. La préparation du substrat garantit que les oeufs soient pondus dans des boulettes de terre, mais déposés dans de la tourbe, ce qui facilite la récolte et la surveillance. Un carabe peut pondre jusqu'à 570 oeufs/femelle, à une température constante de 20 °C. Quel que soit le stade de développement de cette espèce, aucun cannibalisme n'a été observé. Les larves sont élevées intensivement en groupes et nourriesad libitum de vers de terre vivants, ce qui élimine ainsi la nécessité d'apporter régulièrement les aliments et de retirer la nourriture en décomposition. Les expériences d'élevage ont été menées à differents régimes de températures. A une température constante de 20 °C, la croissance s'arrête pendant une longue période chez plusieurs larves de deuxième stade. La réduction de température à 14 °C, durant les 24 à 31 jours après l'éclosion, induit la synchronisation des passages du deuxième au troisième stade larvaire. Le cycle de vie complet, depuis la ponte de l'oeuf jusqu'au carabe adulte, peut être réduit à moins de 110 jours. La mortalité est la plus élevée à la fin du troisième stade larvaire et au stade pré-pupal, et les causes possibles en sont discutées.
    Notes: Abstract Previous work has shown thatAbax parallelepipedus Piller & Mitterpacher preys upon slugs in the field, and can be effectively employed to control slugs in polythene tunnels. To be a viable biological control agent this carabid must also be amenable to mass culturing. Manipulation of the substrate ensured that eggs were laid in soil capsules, but deposited in peat, facilitating collection and monitoring. Up to 570 eggs per beetle were laid at 20°C. No cannibalism was exhibited at any stage by this species. Larvae were reared intensively in batches and fed ad libitum on live earthworms, eliminating the need for regular feeding and the removal of decaying food. Rearing experiments were undertaken under a number of different temperature regimes. At constant 20°C it was found that growth was arrested in some 2nd instar larvae for long periods. Co-ordinated changes between 2nd and 3rd instar stages were induced by reduction of the temperature to 14°C between days 24–31 from hatching. The complete life cycle, from newly laid egg to adult beetle, could be reduced to less than 110 days. Mortality was greatest at the late 3rd instar and pre-pupal stages, and possible reasons for this are discussed.
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  • 33
    ISSN: 1573-8248
    Keywords: Chrysomelidae ; weed ; Acacia ; host specificity ; oviposition ; biological control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé Au Kenya, la chrysomèle phytophage,Weiseana barkeri Jacoby, se nourrit surAcacia nilotica (L.) Willdenow ex Delile. Des essais de spécificité à l'hôte montre que cette espèce est strictement spécifique àA. nilotica: l'autorisation de lâcher dans le nord ouest du Queensland a donc été demandée pour cet auxiliaire carA. nilotica est considérée comme une plante nuisible dans les zones de pacage de troupeaux dans cette région d'Australie. En outre, une nouvelle technique d'élevage et de tests de spécificité à l'hôte est rappotée dans laquelle la présence de feuillage deA. nilotica permet de stimuler l'oviposition deW. barkeri sur des bandes de carton ondulé.
    Notes: Abstract The leaf-feeding beetleWeiseana barkeri Jacoby feeds onAcacia nilotica (L.) Willdenow ex Delile in Kenya. Host specificity tests show it is host specific toA. nilotica and approval has been given for its field release in northwest Queensland. A novel rearing and host specificity-testing technique is reported whereA. nilotica foliage stimulates oviposition into strips of corrugated cardboard.
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  • 34
    ISSN: 1573-8248
    Keywords: biological control ; weeds ; Compositae ; Centaurea ; moths
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé La biologie de la PhalènePterolonche inspersa (Staudinger) (Lepidoptera: Pterolonchidae) a été étudiée dans le Sud de l'Europe. Les larves vivent dans les racines deCentaurea diffusa De Lamarck et deC. maculosa De Lamarck. Les larves de premier stade n'infestent pas les Compositae d'importance économique des genresCynara L.,Helianthus L.,Zinnia L. etCalendula L.P. inspersa est largement répandue dans la zone étudiée, et se retrouve à la fois dans des populations denses ou dispersées de la plante hôte, en général sur des sols sableux ou rocheux. Il n'existe qu'une seule génération par an. Les larves se nourrissent dans les racines pendant environ 11 mois (août–septembre à juillet–août de l'année suivante). Au laboratoire, les adultes émergent entre mi-juillet et fin août, le pic d'émergence se situant à la mi-août. Sur le terrain, les adultes sont observés tout au long du mois de juillet. L'oviposition a été observée à partir du 10 juillet jusqu'à la fin du mois. Les œufs sont déposés isolément ou en groupes de 5 ou 6 sur des rosettes, solidement fixés aux feuilles des plantes-hôtes. Au laboratoire, les adultes s'accouplent au cours des 24 heures suivant l'émergence. La période de pré-oviposition dure 2,6±0,8 jours et la période de l'oviposition 7,4±2,2 jours. Le nombre moyen d'œufs pondus est de 142,2±59,2 par femelle. La durée moyenne d'incubation est de 12±4,7 jours, le stade durant 14,7±2,4 jours. La durée de vie des femelles est supérieure à celle des mâles: 15,8±2,4 au lieu de 10,7±1,4 jours.
    Notes: Abstract The moth,Pterolonche inspersa (Staudinger) (Lepidoptera: Pterolonchidae), is widely distributed in southern Europe, north Africa, Turkey and the former Soviet Union. It occurs in both thick and scattered stands of knapweeds in disturbed sites, usually on sandy and/or stony soil. Larvae bore in the roots of diffuse and spotted knapweeds (Centaurea diffusa De Lamarck andC. maculosa De Lamarck). There is one generation per year in northern Greece, and larvae feed in the roots for about 11 months during the growing season (August–September, to the following July–August). In the laboratory garden, emergence took place between the second half of July and the end of August, with peak emergence during mid August. In the field, adults were observed from early to late July. Female moths oviposited on rosettes during the first ten days of July and continued through the end of July. Eggs were laid singly or in groups of five or six, firmly attached to the leaves of the host plant. In the laboratory, females mated within 24 hours of emergence and the preoviposition period lasted 2.6±0.8 days. The oviposition period lasted 7.4±2.2 days and the average number of eggs per female was 142.2±59.2. The incubation period was 12±4.7 days; the pupal stage lasted 14.7±2.4 days; and females lived 15.8±2.4 days, while males lived 10.7±1.4 days. First instar larvae failed to survive on economically important Compositae in the generaCynara L.,Helianthus L.,Zinnia L. andCalendula L. (Dunnet al., 1989).
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  • 35
    ISSN: 1573-8248
    Keywords: Coccinellidae ; Coleomegilla maculata ; Bacillus thuringiensis ; Leptinotarsa decemlineata ; biological control ; toxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé Des bioessais en laboratoire ont été effectués afin de déterminer si les larves de la coccinelle maculée,Coleomegilla maculata lengi Timberlake (Col.: Coccinellidae), sont affectées par M-One™, un insecticide biologique préparé à partir de la bactérieBacillus thuringiensis var.san diego Berliner et utilisé dans la lutte contre le doryphore de la pomme de terre,Leptinotarsa decemlineata (Say) (Col.: Chrysomelidae). Le développement larvaire, effectué sur du pollen traité avec des concentrations de 20 ml M-One™/litre (5,6×108 unités internationales de doryphore/litre) et 200 ml M-One™/litre, a nécessité 29,3 et 38,5 jours respectivement, comparativement à 21,9 jours pour le témoin (eau). M-One™ n'a pas causé de mortalité chez les larves. Au cours d'un test de 48 h, les larves de stade III n'ont montré aucune préférence entre des œufs traités avec 20 ml M-One™/litre et des œufs traités avec de l'eau. Par contre avec 200 ml M-One™/litre, le nombre d'œufs attaqués a diminué significativement de 34,7% par rapport au témoin, 48 h après le début du test. Ces résultats indiquent que l'utilisation de M-One™ à la concentration recommandée de 20 ml/litre ne représente pas une menace pour les populations larvaires de la coccinelle maculée.
    Notes: Abstract Laboratory experiments were conducted to determine the effects of M-One™ (Bacillus thuringiensis var.san diego) on larval instars ofColeomegilla maculata lengi Timberlake. Coccinellid larval development (from egg hatch to adult), completed on pollen treated with suspensions of M-One™ at 20 ml/litre (5.6×108 CPBIU/litre) and 200 ml/litre, took respectively 29.3 and 38.5 days compared with 21.9 days for the control (water). M-One™ did not cause larval mortality.C. maculata third instars did not show any preference between eggs ofLeptinotarsa decemlineata (Say) treated with water or with M-One™ at 20 ml/litre. However, at 200 ml M-One™/litre, the number of eggs attacked was 34.7% lower than the eggs treated with water only, 48 h after the beginning of the test. These results indicate that the use of M-One™, at the manufacturer's recommended field rate of 20 ml/litre, does not cause a major threat to larvalC. maculata populations.
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  • 36
    ISSN: 1573-8248
    Keywords: Podisus maculiventris ; Leptinotarsa decemlineata ; Pieris brassicae ; biological control ; predation rate ; development rate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé Des recherches de terrain ont été menées afin d'étudier le degré de prédation journalier et l'effet de la proie sur le développement et la survie des différents stades nymphaux deProdisus maculiventris Say en présence de larves du 3e stade deLeptinotarsa decemlineata (Say) et dePieris brassicae (Linnaeus). Les résultats obtenus montrent que les nymphes du 5e stade et les adultes du prédateur ont une importante activité prédatrice avec un taux de survie élevé quand ils se nourrissent aux dépens de larves du doryphore ou de la Piéride du chou. Par conséquent, il est très probable quePodisus pourrait être utilisé contre ces ravageurs dans des zones où les conditions climatiques sont proches de celles de la région de Thessaloniki (Grèce du Nord).
    Notes: Abstract The mean predation rate per day and the effect of the prey on the development and survival of the various nymphal stages ofPodisus maculiventris (Say) were studied under field-cage conditions. Third instar larvae of the Colorado potato beetleLeptinotarsa decemlineata (Say) and the large white butterflyPieris brassicae (Linnaeus) were used as the prey. The results show that under climatic conditions similar to those occurring in the Thessaloniki region (N. Greece), the 5th instar nymphs and the adults of the predatorP. maculiventris would be promising agents for the biological control of larvae ofL. decemlineata andP. brassicae.
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  • 37
    ISSN: 1573-8248
    Keywords: biological control ; cantharid ; supplementary food ; coccinellids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé Chrysophtharta bimaculata Olivier (Col. Chrysomelidae) est un défoliateur important des régénérations d'eucalyptus en Tasmanie: il cause une forte réduction de l'accroissement en hauteur et en diamètre des arbres, réduisant ainsi le cubage de bois produit à l'hectare. En 1991 et 1992, une étude pour conserver et accroître l'efficacité de coccinelles, principalementCleobora mellyi Mulsant (Col.: Coccinellidae), et d'une cantharide,Chauliognathus pulchellus (Macleay) (Col.: Cantharidae) comme agents de lutte biologique, a été faite dans les jeunes peuplements forestiers de Tasmanie du sud pour la lutte biologique deC. bimaculata. Les cantharides adultes et les adultes et larves de coccinelles se nourrissent des œufs deC. bimaculata et à un degré moindre, des jeunes larves. L'activité des coccinelles était la plus importante pendant le stade œuf et les premier et deuxième stades larvaires deC. bimaculata. Les cantharides n'étaient actives que durant le stade œuf de la proie puis disparaissaient de la parcelle. Les coccinelles étaient donc les prédateurs les plus utiles, mais leur population diminuait lorsque la proie atteignait les 3e et 4e stades larvaires. Comme le manque de nourriture pouvait être à l'origine de leur diminution, un complément de nourriture a été fourni sous forme de pulvérisation de saccharose ou de granules de sucre déposées à une station de nourrissage. Ceci a provoqué le maintien des populations des deux prédateurs, particulièrement des coccinelles, et a augmenté leur efficacité.
    Notes: Abstract Chrysophtharta bimaculata (Olivier) (Coleoptera: Chrysomelidae) is a major defoliator of regeneration eucalypt trees in Tasmania causing a significant reduction in height and diameter increment of trees which reduces wood volume per hectare. A study to conserve and enhance the efficiency of coccinellid species chieflyCleobora mellyi (Mulsant) (Coleoptera: Coccinellidae), and the cantharid,Chauliognathus pulchellus (Macleay) (Coleoptera: Cantharidae), for the biological control ofC. bimaculata was conducted in young regeneration forests in southern Tasmania from 1991–92. Cantharid adults and coccinellid adults and larvae feed onC. bimaculata eggs and, to a lesser extent, young larvae. The study found that coccinellids were more active throughout the egg and early (1st and 2nd) stage ofC. bimaculata. The cantharid, however was active only during the egg stage of the prey and then disappeared from the plantation. The coccinellids were therefore the most useful predators, but their population declined when the prey reached the 3rd and 4th stages. As shortage of food may account for this decline, supplementary food was provided in the form of sucrose sprays or sugar granules at a feeding station. This resulted in the retention of both predators and particularly the coccinellids and enhanced their efficacy.
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  • 38
    ISSN: 1573-8248
    Keywords: Aphodius ater ; Aphodius sphacelatus ; Sphaeridium bipustulatum ; Dictyocaulus sp. ; biological control ; Pilobolus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé L'effet de l'activité d'Aphodius spacelatus et deA. ater dans les bouses de vaches et deSphaeridium bipustulatum dans les fèces de moutons et de chevaux, sur la libération de sporanges parPilobolus a été étudié en conditions de laboratoire. Sur 5 essais le nombre médian de sporanges libérés dans des cellules expérimentales (avec 1 ou 2 bousiers/g fèces) était significativement inférieur (P〈0.01) à celui obtenu dans des cellules témoins (sans bousier). De plus, le pourcentage médian de réduction des sporanges est significativement plus élevé (P〈0,01) pourA. sphacelatus (80,9%) que pourA. ater (56,9%) à la densité de 1 bousier/g de bouse.
    Notes: Abstract The effect ofAphodius sphacelatus andA. ater activity in cattle faeces andSphaeridium bipustulatum in sheep and horse faeces on the discharge ofPilobolus sporangia was investigated under laboratory conditions. In five trials, the median number of sporangia produced was significantly less (P〈0.01) in experimental chambers (with 1 or 2 beetles/g faeces) than in control chambers (without beetles). In addition, median percentage reduction of sporangia was significantly higher (P〈0.01) forA. sphacelatus (80.9%) than forA. ater (56.9%) at 1 beetle/g cattle faeces.
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  • 39
    ISSN: 1573-8248
    Keywords: Plutella xylostella ; Diadegma semiclausum ; Cotesia plutellae ; superparasitism ; multiparasitism ; biological control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé Des expériences ont été menées en laboratoire afin d'étudier les caractéristiques du parasitisme dePlutella xylostella (L.), ravageur des crucifères de répartition mondiale, par un parasitoïde larvaire,Diadegma semiclausum Hellén. Les résultats montrent que plus la densité des larves-hôtes est importante, plus le pourcentage de larves parasitées est faible. La surface explorée décroît avec l'augmentation de la densité du parasitoïde mais la valeur de k est pratiquement invariable. Le parasitisme réduit la consommation alimentaire des chenilles. Aucune différence n'est observée quant à la durée des stades larvaires entre larves parasitées et larves non parasitées. La proportion de femelles augmente avec l'accroissement de la fréquence du superparasitisme. La présence de larves du parasitoïde à l'intérieur de la larve-hôte limite davantage le superparasitisme que la présence d'oeufs du parasitoïde. La présence de larves deD. semiclausum ou d'un autre parasitoïde larvaire,Cotesia plutellae Kurdjumov, à l'intérieur des larves-hôtes freine davantage le multiparasitisme par l'une ou l'autre des espèces que la présence d'oeufs de l'un ou l'autre parasitoïde.D. semiclausum est beaucoup plus aggressive queC. plutellae pour parasiter les larves deP. xylostella.
    Notes: Abstract Laboratory experiments were conducted to study the characteristics of parasitism of diamondback moth,Plutella xylostella (L.), a worldwide pest of crucifers, by a larval parasite,Diadegma semiclausum Hellén. Results showed that the greater the host larval density, the lesser was the percentage of larvae parasitized. The area of discovery decreased with increasing parasite density, but k-value remained practically unchanged. Parasitism reduced food consumption in parasitised larvae. No difference was observed in duration of larval instars between the parasitized and healthy larvae. As the frequency of superparasitism increased, the proportion of production of female progeny also increased. Presence of parasite larva within the host larva deterred superparasitism greater than the presence of parasite egg. Presence of larva of eitherD. semiclausum or another larval parasite,Cotesia plutellae Kurdjumov, within host larva deterred multiparasitism by either species greater than the presence of egg of either parasite species.Diadegma semiclausum was much more aggressive thanC. plutellae in parasitisingP. xylostella larvae.
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  • 40
    ISSN: 1573-8248
    Keywords: Dendroctonus micans ; Rhizophagus grandis ; Scolytidae ; Rhizophagidae ; biological control ; mass-rearing ; flight ; take-off ; windtunnel ; quality control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé Le temps passé en conservation à basse température (3–7°C) depuis la métamorphose est intervenu pour 81% dans la perte de la capacité d'envol chez le coléoptère prédateurRhizophagus grandis Gyll. lors d'expériences en tunnel de vol. A l'âge de trois semaines, les insectes sont à leur plus haut niveau d'envol (envol d'environ 80% des insectes). Par la suite, il y a un déclin constant de la capacité d'envol, à raison de 7% des insectes chaque mois. Des changements dans les réserves lipidiques peuvent partiellement expliquer cette réduction, bien qu'il n'y ait pas eu de différence entre le poids frais d'insectes capables de s'envoler et celui d'individus qui en étaient incapables. Le sexe a une influence sur le taux d'envol, avec un taux d'envol significativement plus élevé de 8.7% chez les femelles. La capacité d'envol est encore réduite chez des insectes qui ont été produits dans des élevages de masse où les parents étaient soumis à un mélange de stimuli de ponte de synthèse au lieu d'être mis en présence de larves deD. micans vivantes. Chez les insectes qui prennent leur vol, cependant, la réponse aux attractifs de synthèse est indépendante de l'âge ainsi que des conditions d'élevage.
    Notes: Abstract Time spent by adult beetles in cold storage at 3–7°C accounted for 81% of the loss of take-off capacity inRhizophagus grandis Gyllenhal in windtunnel experiments. At the age of three weeks, the insects were at their highest take-off capacity at about 80%. This was followed by a steady decrease, 7% of the insects failing to take-off each month. Changes in the fat reserves during cold storage could explain at least partly this reduction of flight capacity although there was no significant difference in fresh weight between insects that were able/unable to take-off. Sex had a significant influence on take-off rates, with an 8.7% higher take-off rate in females. Take-off capacity was further reduced when the insects were mass-produced in cultures using parent beetles submitted to a blend of synthetic oviposition stimulants instead of live prey larvae. Response to synthetic attractants by those insects which took-off, however, was not influenced by cold storage or by the use of synthetic stimulants in the culture medium.
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  • 41
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    Nutrient cycling in agroecosystems 36 (1993), S. 127-133 
    ISSN: 1573-0867
    Keywords: hydrology ; water balance ; phosphorus ; Streamflow ; Peel-Harvey
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract This paper discusses the land types, hydrologic characteristics and processes, and the major modification of these, in relation to mechanisms and magnitude of phosphorus losses to drains and riverine systems which discharge to the Peel-Harvey estuary. About 75% of the coastal plain part of the catchment is cleared of native vegetation and used for dryland, dairy and beef grazing. There are small areas devoted to irrigated pasture and commercial horticulture. Seventy-five percent of the soils of the catchment are sandy surfaced with a poor capacity to retain phosphorus. Though the area is flat, catchment water yields are high because of a large winter rainfall excess and low soil storage capacity. Drainage schemes have been constructed in much of the catchment to remove excess water quickly. This was required initially to allow agricultural expansion and is now important for protecting a growing infrastructure which serves the most populous region of Western Australia.
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  • 42
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    Nutrient cycling in agroecosystems 35 (1993), S. 217-226 
    ISSN: 1573-0867
    Keywords: calcium ; dry matter distribution ; fertilizer ; harvest index ; magnesium ; manure ; millet ; nitrogen ; nutrient uptake ; phosphorus ; potassium ; Senegal
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In a fertilizer and manure experiment, millet was grown under four treatments (no fertilizer or manure, farmyard manure, chemical fertilizer, and both). Grain yield and total aboveground biomass production of the unfertilized plot were relatively high. The observed differences in total dry matter production must be attributed to differences in nutrient availability, as amount of rainfall and its distribution were favourable. Results show only small differences in distribution of dry matter among the various plant organs between the best and the non-fertilized treatments. Nutrient supply from natural sources, defined as crop content of N, P, and K at maturity without fertilizer application, amounted to 104, 16 and 103 kg ha−1, respectively, which are very high values. Total uptake of calcium and magnesium is related to that of potassium, as the combined content of these three elements is linearly related to total aboveground biomass production. Minimum removal of nitrogen and phosphorus per ton grain dry matter amounts to 29 and 4kg, respectively, and 9 kg potassium per ton total aboveground dry matter. A possible double function of phosphorus as element of structural biomass and for maintenance of electro-neutrality is discussed.
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  • 43
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    Nutrient cycling in agroecosystems 36 (1993), S. 95-103 
    ISSN: 1573-0867
    Keywords: eutrophication ; phosphorus ; fertilizer ; Peel-Harvey estuary ; algal blooms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract An excess of plant nutrients has caused serious eutrophication in aquatic ecosystems of southwestern Australia manifested by excessive growth and accumulation of green and bluegreen algae. Phosphorus is generally the limiting nutrient for algal growth and phosphatic fertilizers applied to nutrient-deficient, leaching, sandy soils are the main source of P, supplemented by rural industry point sources. Nitrogen is the limiting nutrient in marine embayments with little drainage from the land. Measures to reduce the load of P delivered to drainage include basing fertilizer application rates on soil testing for P and the use of less soluble P fertilizers. Catchment management plans are being implemented with community involvement to reduce P loads and maintain agricultural production. This introductory paper reviews the history of eutrophication in southwestern Australia and of studies into its causes, principally in the large Peel-Harvey estuary. It briefly summarises other papers in this special issue concerned with different aspects of the problem: how to fertilize the land without causing eutrophication.
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  • 44
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    Nutrient cycling in agroecosystems 36 (1993), S. 115-122 
    ISSN: 1573-0867
    Keywords: phosphorus ; retention ; release ; sandy soils
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In order to manage phosphorus (P) losses from soils to waterbodies, knowledge of the mechanisms through which P is retained or released from the soil is essential. Sandy soils of the Peel-Harvey catchment (Western Australia) were subjected to a range of environmental and management factors in the laboratory and field in order to gain an understanding of the mechanisms that affect the magnitude of P losses. Sandy soils accumulated P, despite having little sorption capacity, and this accumulation could be monitored by measuring an acid-extractable fraction. The potential, short-term P loss could be estimated by determination of water-soluble soil solution P prior to winter rains. An annual cycle of the change in arbitrarily defined soil-P pools is discussed in relation to environmental and management factors. Laboratory experiments indicated that P rundown and potential annual P loss in the absence of P fertilizers could be estimated using bicarbonate extractable P. Phosphorus losses were decreased by the application of fertilizers with a low content of water-soluble P. The low ability of sandy soils of the Peel-Harvey coastal catchment to retain P, when compared to other Western Australian soils, is because of low contents of clay minerals and iron and aluminium hydrous oxides.
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  • 45
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    Plant and soil 155-156 (1993), S. 297-300 
    ISSN: 1573-5036
    Keywords: efficiency ; phosphorus ; sowing time ; vernalization ; winter wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The uptake and utilization of phosphorus (P) by cereal crops is influenced by the growing period of the crop. In this article the effect of sowing date on the utilization of P by wheat crops grown in southern NSW is reviewed. Crops sown early in the accepted sowing period require smaller inputs of P fertilizer to reach the maximum yield but produce grain with a higher concentration of P than crops sown late in the sowing season. For later sowings a higher rate of applied P is required to achieve the yield potential but this is not associated with a high grain P concentration or a high rate of removal of P from the soil. If grain with a high P concentration is required as seed for subsequent crops, then sowing early, even with little or no applied P fertilizer, is preferable, although crops sown early in the season are likely to remove more P from the soil than the amount applied in fertilizer.
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  • 46
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    Plant and soil 157 (1993), S. 97-105 
    ISSN: 1573-5036
    Keywords: barley cultivars ; efficiency ; Glomus etunicatum ; Hordeum vulgare ; low temperature ; phosphorus ; response ; VA mycorrhiza
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The purpose of this study was to investigate how barley cultivars which are different in dry matter yield at low phosphorus (P) supply (i.e. they differ in agronomic P efficiency) respond to mycorrhizal infection. In a preliminary experiment, six mycorrhizal fungi were tested for their ability to colonize barley (Hordeum vulgare L.) roots at a soil temperature of 15°C. Glomus etunicatum was the most effective species and was used in the main experiment. The main experiment was conducted under glasshouse conditions in which soil temperature was maintained at 15°C. Treatments consisted of a factorial arrangement of 8 barley cultivars, 2 mycorrhiza (inoculated and non-inoculated), and 3 rates of P (0, 10 and 20 mg kg-1). P utilization efficiency (dry matter yield per unit of P taken up) and agronomic P efficiency among the barley cultivars was significantly negatively correlated with mycorrhizal responses. However, the response to mycorrhizal infection was positively correlated with response to P application. Poor correlation was observed between P concentration when neither mycorrhiza nor P were supplied and the percentage of root length infected. The extent of mycorrhizal infection among the barley cultivars in soil without P amendment varied from 8.6 to 28.6%. Significant interactions between cultivar and P addition, and between mycorrhiza and P addition were observed for shoot dry weight but not root dry weight.
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  • 47
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    Plant and soil 155-156 (1993), S. 45-55 
    ISSN: 1573-5036
    Keywords: compartmentation ; cytoplasm ; 39K NMR ; maize ; nitrogen ; 14N NMR ; 15N NMR ; pea ; phosphorus ; potassium ; 31P NMR ; vacuole
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The cytoplasmic and vacuolar pools of ammonium, inorganic phosphate and potassium can be studied non-invasively in plant tissues using high resolution nuclear magnetic resonance spectroscopy. The techniques that allow these pools to be discriminated in vivo are described and their application to plants is reviewed with reference to the phosphorus, nitrogen and potassium nutrition of root tissues.
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  • 48
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    Plant and soil 151 (1993), S. 143-146 
    ISSN: 1573-5036
    Keywords: iron oxide-impregnated filter paper ; phosphorus ; Pi soil test
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The efficiency of recovery of P by iron oxide-impregnated filter paper, as used in the new Pi test for soil phosphorus, was found to depend on the method used for impregnating the paper with iron oxide and could range from as little as 28% to more than 98%. The greatest efficiency of recovery was obtained with filter papers which had been washed with deionised water following iron oxide-impregnation. These filter papers were also found to give the most reproducible results. ei]{gnB E}{fnClothier}
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  • 49
    ISSN: 1573-5036
    Keywords: bioavailability ; maize ; myo-inositol ; phosphorus ; phytase ; phytin ; soil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effect of adding phytase to the root medium of maize plants on the P-availability of added myo-inositol hexaphosphate (phytin) has been studied in pot experiments. When 40 mM phytin-P in nutrient solution was incubated in quartz-sand for 15 days in the absence of plants, 80% of it could be recovered from the solution as soluble organic P. Maize plants growing on this mixture assimilated P from phytin at rates comparable to those from inorganic phosphate (Pi). At a lower addition rate (2 mM phytin-P) only 10% was recovered in the soil solution, and plant growth was severely limited by P. At this low phytin level, the addition of phytase (10 enzyme units per kg sand) increased the plants' dry weight yield by 32%. The relative increases of the Pi concentration in the solution and of the amount of P in the plants were even higher, indicating that the observed growth stimulation was due to an increased rate of phytin hydrolysis. The enzyme-induced growth stimulation was also observed with plants growing in pots filled with soil low in P, when phytin was added. However, on three different soils the addition rates of phytin and phytase necessary for obtaining a significant phytase effect were both about 10 times higher than those required in quartzsand. It is concluded that the P-availability from organic sources can be limited by the rate of their hydrolytic cleavage.
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  • 50
    ISSN: 1573-5036
    Keywords: critical concentration ; magnesium ; manganese ; nitrogen ; phosphorus ; potassium ; solution culture ; zinc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Solution culture was used to characterise deficiencies or toxicities of several essential elements in Ipomoea batatas cv. Wanmun, and to define the critical concentrations of these elements in young mature leaves during vegetative growth. Tentative critical concentrations for deficiency, expressed on the basis of dry weight of leaf blade, were: nitrogen 3.8%, phosphorus 0.17%, potassium 2.4%, magnesium 0.12%, manganese 20μg/g and zinc 10μg/g. For manganese and zinc toxicities it was possible only to designate the range within which the critical concentration occurred. Visible symptoms are briefly described.
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  • 51
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    Plant and soil 155-156 (1993), S. 277-280 
    ISSN: 1573-5036
    Keywords: allocation ; barley ; efficiency ; Glomus etunicatum ; phosphorus ; VA mycorrhiza
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A glasshouse experiment was undertaken to investigate the effect of mycorrhizal infection on the allocation of phosphorus (P) in agronomically P-efficient (i.e. high yields at low P supply) and inefficient barley (Hordeum vulgare L.) cultivars. Four barley cultivars differing in agronomic P-efficiency were inoculated or not inoculated with Glomus etunicatum. Cultivars did not differ in percentage of root length infected. The concentration of P in roots of the inefficient cultivars was higher than that of the efficient cultivars. However, because of changes in root to shoot dry weight ratio and below-ground productivity, mycorrhizal infection significantly reduced the percentage of total plant P in roots of the inefficient cultivars. The distribution of P between root and shoot of P-efficient cultivars was not affected by mycorrhizal infection. Root to shoot dry weight ratio of the P-efficient cultivars was lower than that of the inefficient cultivars, and the decrease in the ratio following infection was significant in inefficient but not in P-efficient cultivars. This study indicates that mycorrhizal infection alters the allocation of P in inefficient cultivars and effectively improves the efficiency of P utilization with respect to shoot growth.
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  • 52
    ISSN: 1573-5036
    Keywords: benefit ; mycorrhizas ; phosphorus ; revegetation ; root characteristics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We aimed to relate the root characteristics of native plants, with their benefit from mycorrhizal colonization, to assist in developing criteria for predicting plant response to mycorrhizal fungi in revegetated soils. The response of four plant species to VA mycorrhizal fungi was measured at increasing applications of phosphorus (P). The benefit of colonization for all species was large at low rates of P, but declined rapidly for some species at moderate P deficiency. Only then were length and fineness of roots and characteristics of root hairs useful in predicting relative benefit.
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  • 53
    ISSN: 1573-5036
    Keywords: mutant ; 15N isotope dilution ; nitrogen fixation ; nitrogen (N) use efficiency ; nodules ; phosphorus ; phosphorus (P) use efficiency ; roots ; supernodulator
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effect of different levels of soil phosphorus on nodulation, N2 fixation and growth of supernodulating soybean mutant, nts 382, its parent, Bragg, and soybean cultivar, Chippewa, were compared in a greenhouse study. The P rates were, 0, 30, 60 and 90 mg kg−1 soil (P0, P1, P2 and P3, respectively). The reduced shoot growth of nts 382 (25% at P0 and 17% at P3) could not be attributed to P deficiency, as nts 382 achieved near maximum yield at a lower P rate (P1) than Bragg (P2). The P response of Chippewa that produced the lowest shoot yield, was similar to that of Bragg. Root growth of nts 382 was more retarded than shoot growth (on average 50% that of Bragg), and yet absorbed a similar amount of total P as Bragg. Also, Chippewa that had the lowest root dry matter accumulated the highest P in the shoots. The data indicate that plant growth was influenced by differences in P use efficiency rather than differences in total P. In contrast to plant growth, nts 382 accumulated 26% more N than Bragg, and Chippewa accumulated a similar amount of N as Bragg. Thus again, Bragg used N most efficiently for growth. Soil N uptake was not governed by root biomass, and Chippewa absorbed more N from soil than both Bragg and nts 382 which absorbed similar amounts of soil N. Nodulation in nts 382 was significantly enhanced, being 528 and 892% greater than Bragg at P0 and P3, respectively, and nts 382 was the only cultivar whose nodulation was consistently enhanced by P addition. The percentage of N derived from fixation (% Ndfa) was not affected by supernodulation, but because of a greater accumulation of total N in nts 382, amount of N fixed (Ndfa) was on average 30% higher in nts 382 than Bragg. Also, while % Ndfa in either nts 382 or Bragg was not influenced by P addition, total N and consequently, Ndfa increased. However, for Chippewa which fixed the lowest N, both % Ndfa and Ndfa were increased by P addition. We conclude that although supernodulation had an adverse effect on shoot and root growth, these reductions could not be attributed to a reduced uptake of the two major plant nutrients, N and P, neither was there evidence that the mutation had caused a greater demand for these nutrients, other than for the greater requirement of P for nodulation. ei]{gnR O D}{fnDixon}
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  • 54
    ISSN: 1573-5036
    Keywords: ectomycorrhizal fungi ; eucalypts ; growth response ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effectiveness of 16 fungal isolates in forming ectomycorrhizas and increasing the growth and phosphorus uptake of Eucalyptus globulus Labill. and E. diversicolor F. Muell. seedlings was examined in the glasshouse. Seedlings were grown in yellow sand at 2 phosphorus levels (4 and 12 mg P kg-1 sand). At the time of harvest (100 days), the non-inoculated seedlings and seedlings inoculated with Paxillus muelleri (Berk.) Sacc. and Cortinarius globuliformis Bougher had a low level of contamination from an unknown mycorrhizal fungi. Seedlings inoculated with Thaxterogaster sp. nov. and Hysterangium inflatum Rodway had developed mycorrhizas of the superficial type whereas Hydnangium carneum Wallr. in Dietr., Hymenogaster viscidus Massee & Rodway, Hymenogaster zeylanicus Petch, Setchelliogaster sp. nov., Laccaria laccata (Scop. ex. Fr.) Berk., Scleroderma verrucosum (Vaillant) Pers., Amanita xanthocephala (Berk.) Reid & Hilton, Descolea maculata Bougher and Malajczuk and Pisolithus tinctorius (Pers.) Coker & Couch formed typical pyramidal ectomycorrhizas. The dry weight of non-inoculated and inoculated E. globulus seedlings at 12 mg P kg-1 sand did not differ, whereas several isolates caused growth depression of E. diversicolor. By contrast, at 4 mg P kg-1 sand growth increases ranged from 0–13 times above that of non-inoculated seedlings. P. tinctorius produced the largest growth increase on both eucalypt species. In general, isolates which developed more extensive mycorrhizas on roots produced the largest growth responses to inoculation. Isolates which increased plant growth also increased phosphorus uptake by the plant. Seedlings inoculated with L. laccata and S. verrucosum retained more phosphorus in their roots than plants inoculated with the other fungal isolates.
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  • 55
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    Plant and soil 157 (1993), S. 97-105 
    ISSN: 1573-5036
    Keywords: barley cultivars ; efficiency ; Glomus etunicatum ; Hordeum vulgare ; low temperature ; phosphorus ; response ; VA mycorrhiza
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The purpose of this study was to investigate how barley cultivars which are different in dry matter yield at low phosphorus (P) supply (i.e. they differ in agronomic P efficiency) respond to mycorrhizal infection. In a preliminary experiment, six mycorrhizal fungi were tested for their ability to colonize barley (Hordeum vulgare L.) roots at a soil temperature of 15°C.Glomus etunicatum was the most effective species and was used in the main experiment. The main experiment was conducted under glasshouse conditions in which soil temperature was maintained at 15°C. Treatments consisted of a factorial arrangement of 8 barley cultivars, 2 mycorrhiza (inoculated and non-inoculated), and 3 rates of P (0, 10 and 20 mg kg-1). P utilization efficiency (dry matter yield per unit of P taken up) and agronomic P efficiency among the barley cultivars was significantly negatively correlated with mycorrhizal responses. However, the response to mycorrhizal infection was positively correlated with response to P application. Poor correlation was observed between P concentration when neither mycorrhiza nor P were supplied and the percentage of root length infected. The extent of mycorrhizal infection among the barley cultivars in soil without P amendment varied from 8.6 to 28.6%. Significant interactions between cultivar and P addition, and between mycorrhiza and P addition were observed for shoot dry weight but not root dry weight.
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  • 56
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    Plant and soil 155-156 (1993), S. 293-296 
    ISSN: 1573-5036
    Keywords: efficiency ; genotypic differences ; phosphorus ; Triticum aestivum ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In an attempt to evaluate whether breeding and selection for high yielding capacity did change the P requirements of modern wheat cultivars, the response of two wheat cultivars to different levels of P supply was investigated. A traditional cultivar ("Peragis") and a modern cultivar ("Cosir") were cultivated in a C-loess low in available P and high in CaCO3 in 120 cm high PVC pots. Shoot and root growth at different developmental stages was compared. The grain yield of the modern cultivar Cosir was higher at limiting and non-limiting P supply and, therefore, this cultivar can be considered as more P-efficient than the traditional cultivar. From the results it can be concluded that the main factors contributing to the higher P efficiency of the modern cultivar are (i) efficient use of assimilates for root growth characteristics which enhance P acquisition: smaller root diameter, and longer root hairs, (ii) efficient remobilization of P from vegetative plant organs to the grains, and (iii) lower P requirement for grain yield formation because of lower ear number per plant but higher grain number per ear.
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  • 57
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    Plant and soil 150 (1993), S. 33-39 
    ISSN: 1573-5036
    Keywords: droguth tolerance ; phosphorus ; photosynthesis ; plant nutrition ; plant water relations ; Pseudotsuga menziesii ; stomatal conductance ; water stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A growth chamber experiment was conducted to determine if P fertilization to enhance the P nutrition of otherwise N and P deficient Douglas fir [Pseudotsuga menziesii (Mirb.) Franco] seedlings reduces water stress in the seedlings during drought periods. Seedlings were grown in pasteurized mineral soil under well-watered conditions and fertilized periodically with a small amount of nutrient solution containing P at either of three levels: 0, 20, or 50 mg P L-1. By age 6 mo, leaf nutrient analysis indicated that N and P were deficient in control (0 mg P L-1) seedlings. The highest level of P fertilization, which doubled leaf P concentration, did not affect plant biomass, suggesting that N deficiency was limiting growth. When these seedlings were subjected to drought, there was no effect of P fertilization on leaf water potential or osmotic potential. Furthermore, P fertilized seedlings had lower stomatal conductance and net photosynthesis rate. These results indicate that enhanced P nutrition, in the presence of N deficiency, does not reduce water stress in Douglas fir seedlings during drought periods.
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  • 58
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    Plant and soil 150 (1993), S. 61-68 
    ISSN: 1573-5036
    Keywords: calciaquoll ; FeEDDHA ; iron ; Linum usitatissimum L. ; manganese ; phloem mobility ; phosphorus ; post-flowering N stress ; zinc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Seed of flax (Linum usitatissimum L.) grown on calcareous and neutral soils sometimes accumulates relatively high concentrations of Cd. The influence of a post-flowering application of NH4NO3 (115 mg N kg-1), CdSO4 (1 mg Cd kg-1), FeEDDHA (2 mg Fe kg-1), NaH2PO4 (120 mg P kg-1) and ZnSO4 (8 mg Zn kg-1) on seed accumulation of Cd, Fe, N, Mn, P and Zn by flax grown on a Calciaquoll was studied in two experiments under greenhouse conditions. Seed yields were increased by the N and Zn treatments, and the N×Zn interaction was positive. Zinc deficiency delayed flowering and boll formation by up to 20 days and reduced seed size. In the absence of added Cd, seed accumulated up to 0.33 mg Cd kg-1. This Cd accumulation was reduced by approximately 50 and 17% by added Zn and Fe, respectively, but was little affected by P fertilizer and post-flowering N stress. In the presence of added Cd, seed Cd exceeded 3.3 mg Cd kg-1, and the antagonistic effects of Fe and Zn on seed Cd were absent. Seed N, P, Fe and Zn concentrations were increased on average by 10, 45, 31 and 97% by the N, P, Fe and Zn fertilizer treatments, respectively. FeEDDHA reduced seed Mn concentration by approximately 58%. However, seed Mn concentration was much less than that found in vegetative tissue at flowering. Soil-applied Zn may reduce seed Cd concentration in flax under field conditions, and may increase marketability of flax for food use.
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  • 59
    ISSN: 1573-5036
    Keywords: bean ; 15N isotope ; nitrogen fixation ; N fertilizer ; phosphorus ; potassium ; Rhizobium tropici ; sulphur
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Although common bean (Phaseolus vulgaris L.) has good potential for N2 fixation, some additional N provided through fertilizer usually is required for a maximum yield. In this study the suppressive effect of N on nodulation and N2 fixation was evaluated in an unfertile soil under greenhouse conditions with different levels of soil fertility (low=no P, K and S additions; medium = 50, 63 and 10 mg kg−1 soil and high = 200, 256 and 40 mg kg−1 soil, respectively) and combined with 5, 15, 60 and 120 mg N kg−1 soil of 15N-labelled urea. The overall average nodule number and weight increased under high fertility levels. At low N applications, nitrogen had a synergistic effect on N2 fixation, by stimulating nodule formation, nitrogenase activity and plant growth. At high fertility and at the highest N rate (120 mg kg−1 soil), the stimulatory effect of N fertilizer on N2 fixation was still observed, increasing the amounts of N2 fixed from 88 up to 375 mg N plant−1. These results indicate that a suitable balance of soil nutrients is essential to obtain high N2 fixation rates and yield in common beans.
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  • 60
    ISSN: 1573-5036
    Keywords: carbon ; fertiliser ; fractionation ; pH ; phosphorus ; soil ; soil solution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The influence of soil acidity and phosphorus fertilization on phosphorus fractions and dissolved organic carbon (DOC) in soil solution was quantified experimentally in an iron humus podzol. Soil solution was isolated by centrifugation from top- and sub-soil samples. Total dissolved phosphorus (TDP), dissolved reactive phosphorus (DRP), dissolved organic phosphorus (DOP) and DOC increased as soil pH and P status increased. DOP was the fraction present at the highest concentration (0.080–0.464 mg P L−1) for the majority of samples. DOC and DOP concentrations which remained relatively constant down the soil profile were also highly correlated. Soluble organic P compounds may make a significant contribution to plant available soil P particularly for soils with low fertility levels. The relatively high DOP concentrations (ca 0.227 mg P L−1) found throughout the soil profile have important consequences with regards to P leaching and plant nutrition.
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  • 61
    ISSN: 1573-5095
    Keywords: eucalypt ; regrowth forest ; litter ; litterfall ; fertilizer ; nitrogen ; nutrient cycling ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of fertilizer treatment on nutrient transfers to the forest floor were examined in regrowth Eucalyptus diversicolor F. Muell. forest. Dry weight and nutrient content of leaf litterfall and total litterfall were measured for 3 years in a stand to which two levels of N (0, 200 kg ha-1 year-1) were applied each year at each of three levels of a single initial application of P (0, 30, 200 kg ha-1). Annual accessions of litter to the forest floor were significantly increased by additions of both N (by 17%, 18% and 21% in the 3 years) and 200 kg P ha-1 (by 8%, 8% and 4% in the 3 years) but there was no interaction between effects of N and P treatments. Fertilizer application also had a significant effect on the nutrient content of leaf litterfall and total litterfall. Concentration of N in leaf litterfall was 9% to 23% greater on plots treated with N fertilizer compared to untreated plots. The amounts of N in litterfall were about 30% greater on N-treated compared to untreated plots. On plots treated with 200 kg P ha-1, P concentrations in leaf litter were 50% to 100% greater than in litter from plots receiving no P. Application of 200 kg P ha-1 increased the amounts of P in annual litterfall by 32% to 87%. The greatest increase in P accessions occurred soon after fertilizer treatment. The amounts of Ca, K, and Na in litterfall were also significantly increased by fertilizer application. For Ca and K this was due partly to increases in element concentrations in litterfall following application of treatments. The effect of fertilizers on internal recycling of plant nutrients and on litter accumulation and nutrient dynamics in forest floor litter is discussed.
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  • 62
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    Nutrient cycling in agroecosystems 36 (1993), S. 79-90 
    ISSN: 1573-0867
    Keywords: agriculture ; Sahel ; Sudan ; Mali ; cotton ; fertilization ; nutrient ; soil ; soil degradation ; depletion ; nutrient ; nutrient balance ; nitrogen ; phosphorus ; potassium ; calcium ; magnesium ; acidification ; sustainability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The degree of soil mining by agricultural production in Southern Mali is assessed by calculating nutrient balances: differences between the amount of plant nutrients exported from the cultivated fields, and those added to the fields. Export processes include extraction by crops, losses due to leaching, to erosion, and to volatilization and denitrification. Inputs include applications of fertilizer and manure, restitution of crop residues, nitrogen fixation, atmospheric deposition of nutrients in rain and dust, and enrichment by weathering of soil minerals. Nutrient balances are calculated for N, P, K, Ca, and Mg. Both pessimistic and optimistic estimates are given. The resulting figures indicate, even when the most optimistic estimates are used, large deficits for nitrogen, potassium and magnesium. For the region as a whole, the calculated deficits are -25 kg N/ha,-20 kg K/ha, and -5 kg Mg/ha. Further, acidification is to be expected, in particular in areas where cotton is grown. The deficits are caused by traditional cereal crops, but also by cotton and especially by groundnut. The latter two crops are fertilized, but insufficiently. It is important to note, that the negative figures are not automatic recommendations for application of a specific amount of additional fertilizer. For phosphorus and calcium the balance of the region as a whole appears to be about in equilibrium, but locally large variations may occur. Erosion and denitrification are important causes of nutrient loss, accounting respectively for 17 and 22% of total nitrogen exports. Atmospheric deposition and weathering of minerals in the soil are still important nutrient inputs that contribute as much as nutrients as organic and mineral fertilizer combined. Nutrient depletion is very large in comparison to the amount of fertilizer applied. Drastic options, such as doubling the application of fertilizer or manure, or halving erosion losses, even if feasible, would still not be enough to make up for the calculated deficits. The annual value of withdrawn nutrients, if related to prices of fertilizers, varies between 10,000 and 15,000 FCFA/ha (40-60 US $/ha). Since the estimated average gross margin from farming in this area is 34,000 FCFA/ha (123 US $/ha), soil mining appears to provide an amount equal to 40% of farmers' total income from agricultural activities.
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  • 63
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    Nutrient cycling in agroecosystems 36 (1993), S. 105-114 
    ISSN: 1573-0867
    Keywords: eutrophication ; phosphorus ; algae ; cyanobacteria ; seagrasses ; plankton ; benthic fauna
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Water bodies in coastal areas of southwestern Australia are predisposed to eutrophication. The sandy soils of the catchments retain nutrients poorly, streamflow is highly seasonal, most freshwater wetlands are small and shallow, and the estuaries are poorly flushed. Nearshore waters lack the conventional upwelling of other coastal regions in these latitudes. Consequences include increased macroalgal growth and phytoplankton blooms, especially of cyanobacteria, and loss of seagrasses. Changes to fish and invertebrate populations result both from increased algal production and low oxygen concentrations. Algal toxins and outbreaks of botulism have caused waterbird casualties. Phosphorus is especially important in controlling plant biomass in freshwater wetlands and estuaries, and N in some wetlands and coastal embayments. In the examples reviewed here nutrients are derived mainly from fertilizer applications in catchments and rural industries, and from sewage and individual discharges to coastal waters.
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  • 64
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    Nutrient cycling in agroecosystems 36 (1993), S. 157-164 
    ISSN: 1573-0867
    Keywords: phosphorus ; wetlands ; nutrient uptake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Natural and artificial wetlands have the potential to reduce phosphorus (P) loads from dispersed agricultural runoff and from point sources in the Peel-Harvey catchment, Western Australia. Small experimental systems containing wetland plants and substrate have shown significant removal of P from inflowing water, the proportion of P removed being dependent on P concentration and flow rate of water through the system. The use of artificial wetlands to treat diffuse agricultural runoff is limited by the highly seasonal runoff typical of this Mediterranean climate, while use at point sources has so far been unsuccessful because compounds from the effluent clog the wetland ‘filters’. Treatment at point sources may well be feasible after further research. Natural wetlands in the catchment absorb P received in runoff from farmland and, in the absence of any outflow channels to the drainage system, confine this P within the boundaries of the wetland. Disturbance to wetlands may reduce their efficiency in absorbing nutrients and may release P stored in the vegetation and sediment to the water. The conservation of natural wetlands is recommended to maximise nutrient retention in the catchment.
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  • 65
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    Nutrient cycling in agroecosystems 36 (1993), S. 165-170 
    ISSN: 1573-0867
    Keywords: phosphorus ; nutrient loss ; management ; point sources
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Nutrient loss from rural point sources and urban environments need to be minimised as part of strategies to overcome declining water quality on the Swan Coastal Plain and in the Peel-Harvey estuary in Western Australia. This paper discusses the management of nutrient losses from domestic effluent, urban stormwater runoff, domestic gardens and public open space, intensive animal industries and intensive irrigated agriculture. Measures to minimise nutrient losses from these sources are outlined, using cooperative, technological and regulatory approaches.
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  • 66
    ISSN: 1573-5036
    Keywords: liming ; nutrient uptake ; phosphorus ; Stylosanthes guianensis ; tropical soil ; vesiculararbuscular mycorrhiza
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The nutrient concentration in the shoots ofStylosanthes guianensis (Aubl.) Sw. cultivated in a sterilized acid and dystrophic soil (Quartzipsament) amended with 4 levels of lime (0; 0.27; 0.63 and 1.10 meq Ca2+/100 g soil, as Ca(OH)2), 2 levels of P (0 and 20 mg P kg-1 soil, as KH2PO4) and not-inoculated or inoculated with 3 vesicular-arbuscular (VA) mycorrhizal fungi was evaluated under greenhouse conditions. The effectiveness of the different fungal species in increasing the nutrient concentration in the shoots varied with the different edaphic conditions. In general, mycorrhiza formation was associated with increases in the concentrations of most of the nutrients analyzed. Under the experimental conditions, the increments in nutrient concentration were higher overall in plants inoculated withAcaulospora scrobiculata. Inoculation ofS. guianensis with VA mycorrhizal fungi was also associated with alterations in the ratios of nutrients in the shoots, which might be important in understanding and explaining the tolerance of mycorrhizal plants to nutritional stresses such as Al and Mn toxicity.
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  • 67
    ISSN: 1573-5060
    Keywords: Wheat ; Triticum aestivum ; landrace ; semidwarf ; phosphorus ; nitrogen ; fertilization ; genetic improvement ; breeding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In recent decades, most winter wheat (Triticum aestivum L.) breeding in the United States has been done in field nurseries in which the soil receives ample fertilization. To determine the effects of these breeding efforts on productivity under low-fertility conditions, we evaluated twenty-nine winter wheat genotypes (seven Asian landraces; thirteen standard-height U.S. cultivars released between 1874 and 1971; and nine semidwarf cultivars released between 1977 and 1988) under severe fertility stress at three Kansas, USA locations. Experiments included fertilized and unfertilized treatments. The modern, semidwarf cultivars yielded 18% and 20% more, on average, than landraces and standard-height cultivars under low and high fertility, respectively; however, only the latter difference reached the 5% significance level. At only one location (Hays) was there a significant genotype X fertility interaction: there, 89% of the semidwarf cultivars, only 8% of the standard cultivars, and 57% of the landraces responded to fertilization. The regression coefficient of mean grain yield (unfertilized) on year of introduction or release for standard and semidwarf cultivars was zero, indicating that a century of breeding has produced no genetic improvement in performance under these low-fertility conditions. Although we found that the usual yield advantage of modern cultivars is not expressed under very low fertility, we saw no evidence that older cultivars are superior under those conditions.
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  • 68
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    Biogeochemistry 21 (1993), S. 141-166 
    ISSN: 1573-515X
    Keywords: acetylene reduction ; agroecology ; natural abundance15N ; nitrogen fixation ; phosphorus ; sustainable agriculture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Although nitrogen is considered to be the nutrient that most commonly limits production of natural and managed terrestrial ecosystems, I propose that phosphorus may regulate productivity in many continuously cultivated agroecosystems that do not receive applications of synthetic fertilizers. One way P may limit agroecosystem productivity is by controlling nitrogen fixation of legume crops, thus affecting nitrogen availability in the overall agroecosystem. I tested this hypothesis in two studies by examining the effect of phosphorus nutrition on nitrogen fixation of alfalfa in traditional Mexican agroecosystems. All farms used in the research relied on alfalfa as the primary nitrogen source for maize cultivation and other crops, and had minimal or no reliance on synthetic fertilizers. In one study, I used the natural abundance of15N to estimate nitrogen fixation in five alfalfa plots with soils representing a wide range of P fertility. I found a correlation of r = 0.85 between foliage P concentrations and nitrogen fixation in the alfalfa plots. Mean nitrogen fixation in alfalfa plots ranged between 232–555 kg ha−1 yr−1 as estimated by the15N-natural abundance method. In a second study, I sampled soils from alfalfa plots on traditional farms located in 5 different physiographic regions of Mexico. Half of each soil sample was augmented with phosphorus in a greenhouse experiment. I grew alfalfa on the fertilized and unfertilized soils from each site and then determined nitrogenase activity (acetylene reduction) of the Rhizobium on the plant roots. Nitrogenase activity increased in the alfalfa grown on all soils with added phosphorus, with two of the five differences being statistically significant at P 〈 0.01, 0 and one at P 〈 0.05. Foliage P concentrations and nitrogenase activity were 0 positively correlated (r = 0.81,P 〈 0.01).0
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  • 69
    ISSN: 1573-515X
    Keywords: chronosequence ; montane tropical forest ; nitrogen ; soil development ; phosphorus ; tropical forest
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract We determined the effects of nutrient amendments on plant growth in three tropical montane rainforest sites representing a sequence of soil ages (〈 30, 200, and ≈ 2000 y). Factorial fertilization with nitrogen, phosphorus, and all other essential nutrients (combined) was applied to the two younger sites; only nitrogen was applied to the oldest one. Nitrogen supply represented the most important limitation to plant growth in the two younger sites; additions of nitrogen caused significant increases in tree diameter increment, height growth, litterfall, and most other growth-related parameters. In contrast, nitrogen additions had no significant effect on plant growth in the oldest site. Phosphorus additions increased extractable soil phosphorus and plant tissue phosphorus, but did not increase plant growth at the young sites. The results are consistent with Walker & Syers' (1976) model for the control of nutrient limitation during soil development.
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  • 70
    ISSN: 1573-8469
    Keywords: antibiosis ; biological control ; disease resistance ; Fusarium oxysporum f.sp.dianthi ; root colonization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The mechanisms of suppression of fusarium wilt of carnation by two fluorescentPseudomonas strains were studied. Treatments of carnation roots withPseudomonas sp. WCS417r significantly reduced fusarium wilt caused byFusarium oxysporum f. sp.dianthi (Fod). Mutants of WCS417r defective in siderophore biosynthesis (sid−) were less effective in disease suppression compared with their wild-type. Treatments of carnation roots withPseudomonas putida WCS358r tended to reduce fusarium wilt, whereas a sid− mutant of WCS358 did not. Inhibition of conidial germination of Fod in vitro by purified siderophores (pseudobactins) of bothPseudomonas strains was based on competition for iron. The ferrated pseudobactins inhibited germination significantly less than the unferrated pseudobactins. Inhibition of mycelial growth of Fod by bothPseudomonas strains on agar plates was also based on competition for iron: with increasing iron content of the medium, inhibition of Fod by thePseudomonas strains decreased. The sid− mutant of WCS358 did not inhibit Fod on agar plates, whereas the sid− mutants of WCS417r still did. This suggests that inhibition of Fod by WCS358r in vitro was only based on siderophore-mediated competition for iron, whereas also a non-siderophore antifungal factor was involved in the inhibition of Fod by strain WCS417r. The ability of thePseudomonas strains to induce resistance against Fod in carnation grown in soil was studied by spatially separating the bacteria (on the roots) and the pathogen (in the stem). Both WCS417r and its sid− mutant reduced disease incidence significantly in the moderately resistant carnation cultivar Pallas, WCS358r did not. It is concluded that the effective and consistent suppression of fusarium wilt of carnation by strain WCS417r involves multiple mechanisms: induced resistance, siderophore-mediated competition for iron and possibly antibiosis. The less effective suppression of fusarium wilt by WCS358r only depends on siderophore-mediated competition for iron.
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  • 71
    ISSN: 1573-8248
    Keywords: Lymantria dispar ; gypsy moth ; pupal parasitism ; density dependence ; biological control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé Le parasitisme nymphal deLymantria dispar a été étudié dans 15 placettes du New Jersey, de 1978 à 1988. Le principal parasitoïde était un chalcidien,Brachymeria intermedia (Nees), qui n'a été trouvé que dans 6 placettes. Le parasitisme s'observait généralement dans l'année même ou dans celle précédant l'apparition du maximum d'ooplaques deL. dispar. Un seul site montrait un taux de parasitisme dépassant 4%. Le pourcentage de parasitisme était significativement corrélé avec le nombre d'ooplaques par ha de la saison en cours et avec le nombre de nymphes par site de la saison précédente, suggérant une densité-dépendance retardée. Une analyse de régression multiple a révélé un pourcentage de parasitisme significativement corrélé avec le pourcentage d'infection par le virus de la polyhédrose nucléaire, la densité de nymphes hôtes mâles, les températures minimales moyennes en août et en mars. Une analyse canonique discriminante, effectuée pour différencier les sites avec ou sans parasitoïdes, a été significative. Les placettes avecB. intermedia présentent des populations d'hôtes et une défoliation relativement plus élevées.
    Notes: Abstract Pupal parasitism of the gypsy moth,Lymantria dispar (L.), was monitored in 15 study plots in New Jersey from 1978 to 1988. The predominant parasitoid was a chalcidid wasp,Brachymeria intermedia (Nees), which was found in only six plots. Parasitism was generally observed in the year of or preceding the peak numbers of gypsy moth egg masses. Parasitism exceeded 4% in only one plot. Percentage parasitism was correlated significantly with numbers of egg masses per hectare in the current season and with numbers of pupae per plot in the previous season, suggesting delayed density dependence. A multiple regression analysis found percentage parasitism to be correlated significantly with percentage infection by nuclear polyhedrosis virus, density of male host pupae, and mean minimum temperature in August and March. A canonical discriminant analysis carried out to distinguish study plots with and without the parasitoid was significant. Plots withB. intermedia had relatively higher host populations and defoliation.
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  • 72
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    BioControl 38 (1993), S. 3-6 
    ISSN: 1573-8248
    Keywords: biological control ; thelytoky ; arrhenotoky ; sexual reproduction ; asexual reproduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 73
    ISSN: 1573-8248
    Keywords: Psyllaephagus ; Tamarixia ; Heteropsylla ; biological control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé La fécondité en fonction de l'âge de deux parasitoïdes du psylleHeteropsylla cubana, Psyllaephagus yaseeni etTamarixia leucaenae a été étudiée en condition de laboratoire. A 25 °C,P. yaseeni présente une fécondité plus élevée (R0=192,9) queT. leucaenae (R0=71,2);T. leucaenae montre cependant une sex ratio plus faible (environ 99 % de femelles) queP. yaseeni (environ 50 %). Le taux d'accroissement potentiel (rm=0,236) deT. leucaenae était plus élevé que celui deP. yaseeni (rm=0,188). Les vitesses de développement des parasitoïdes ont été examinées à des températures constantes et fluctuantes et les équations de la vitesse de développement en fonction de la température ont été calculées. A 25 °C, la durée moyenne des générations était respectivement de 28,0 et 18,1 jours pourP. yaseeni etT. leucaenae. Aux températures de 21,5, 25 et 30 °C la durée totale de développement (de l'œuf à l'adulte) était de 28,5, 21,9 et 14,7 jours chezP. yaseeni et 19,2, 12,6 et 9,5 jours chezT. leucaenae. Le taux de parasitisme était faible et la mortalité nymphale était élevée à la température la plus basse, 21,5 °C, pour les deux parasitoïdes. Tous deux présentaient une survie faible à 100 % de HR;P. yaseeni survivait particulièrement bien à une température de 21 °C et à 44 ou 76% d'HR. P. yaseeni attribuait environ 58 % de femelles aux larves de premier stade de développement mais seulement 12 % aux larves de second stade. Environ 99 % de toutes les éclosions deT. leucaenae était constituée de femelles. La taille des femelles issues des larves de 5e stade étaient significativement supérieure à la taille de celles qui émergeaient des larves de 3e ou 4e stade.
    Notes: Abstract Age specific fecundity of two parasitoids,P. yaseeni andT. leucaenae, of the leucaena psyllidH. cubana, were studied under laboratory conditions. At 25 °C,P. yaseeni had a greater fecundity (R0=192.9)_thanT. leucaenae (R0=71.2);T. leucaenae however had a lower sex ratio (about 99 % females) thanP. yaseeni (about 50 % females). Innate capacity for increase (rm=0.236) ofT. leucaenae was higher thanP. yaseeni (rm=0.188). Developmental rates of the parasitoids were examined at constant and fluctuating temperatures and equations of the rate of development against temperature were calculated. At 25 °C, mean generation times were 28.0 and 18.1 days forP. yaeseeni andT. leucaenae respectively. At temperatures of 21.5, 25, and 30 °C total development times (egg to adult) were 28.5, 21.9, and 14.7 days inP. yaseeni and 19.2, 12.6, and 9.5 days inT. leucaenae respectively. The level of parasitism was low and pupal mortality was high at the lower temperature of 21.5 °C for both parasitoids. Both parasitoids showed poor survivorship at 100 % RH,P. yaseeni survived particularly well (32 days) at a temperature of 21.5 °C and 44 or 76 % RH. P. yaseeni allocated about 58 % females to first instar psyllid nymphs but only 12 % females to second instars. About 99 % of allT. leucaenae births were females. Significantly largerT. leucaenae females emerged from fifth instar parasitized nymphs than third or fourth instars.
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  • 74
    ISSN: 1573-8248
    Keywords: parasitoid ; biological control ; heat shock
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé Suite à une efficacité parasitaire faible des trichogrammes, constatée, dans des conditions climatiques particulières lors des lâchers de ces parasitoïdes contre la pyrale du maïs, des chocs thermiques à 35°C et 44°C pendant une durée de 6 heures sont appliqués au stade nymphal deTrichogramma brassicae Bezdenko. Deux âges sont choisis: nymphe blanche et nymphe mélanisée. Différents critères biologiques ont été étudiés pour la génération G0 ayant subi le choc de température et pour les descendants G1. Les résultats obtenus indiquent une sensibilité des deux âges, surtout à 44°C. Cette température provoque une réduction du pouvoir parasitaire de la G0 de 51% pour les individus issus des nymphes blanches traitées et de 55% pour ceux issus des nymphes mélanisées traitées. Au niveau de la génération G1, on constate une chute de la proportion des femelles dans la descendance des adultes issus des deux âges traités: réduction de 38% pour les individus issus des nymphes mélanisées; 88% pour ceux issus des nymphes blanches. Dans ce dernier cas, la génération G1 pratiquement totalement mâle, est obligatoirement sans efficacité parasitaire.
    Notes: Abstract Trichogramma brassicae Bezdenko is used throughout Europe as an effective biological control agent against the European corn borer (Ostrinia nubilalis Hübner). However, in certain climatic regions, the biological control exerted by this parasitoid is less effective. High temperatures inside the released capsules are suspected to have a negative influence on the parasitoids. To simulate these adverse conditions, we applied heat shocks (35°C and 44°C) for 6 hours to pupae ofTrichogramma brassicae at two periods: white pupae and melanized pupae. The results showed the susceptibility of both the white pupae and melanized pupae, especially at 44°C. At this temperature, the adults (G0 generation) derived from pupae treated at any age showed reduced longevity and fecundity. Moreover, those descended from treated melanized pupae showed an emergence rate lower than that of the control. These effects reduced to half and more the parasitic efficiency of the G0 generation. For the progeny (G1 generation), we observed a decrease of the female ratio: 38% for the progeny of adults derived from treated melanized pupae; 88% for the progeny of those derived from treated white pupae. In that condition, the G1 generation, almost totally male, could not have any parasitic activity.
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  • 75
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    BioControl 38 (1993), S. 193-198 
    ISSN: 1573-8248
    Keywords: biological control ; predation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé Des expériences menées en conditions contrôlées dans des boîtes carrées semées de trèfle ou de ray grass ont montré que les CarabesAbax parallelepipedus (Piller & Mitterpacher) etPterostichus madidus F. limitent les populations de limaces dans les champs de trèfle et de ray grass. La limitation par ces carabes se révèle aussi bonne que celle obtenue avec le molluscicide methiocarb.A. parallelepipedus semble plus efficace queP. madidus dans ce rôle, les dégâts sur le trèfle étant maintenus à un minimum.P. madidus ne limite les limaces qu'une fois le trèfle déjà attaqué.
    Notes: Abstract Experiments conducted in sward boxes under controlled conditions showed that the carabid beetlesAbax parallelepipedus (Piller & Mitterpacher) andPterostichus madidus F. controlled slugs in a grass/clover sward. Control was shown to be as good as that by the molluscicide, methiocarb.A. parallelepipedus proved to be more successful thanP. madidus at controlling the slugs, damage to the clover being kept to a minimum.P. madidus controlled the slugs only after some damage to the clover was sustained.
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  • 76
    ISSN: 1573-8248
    Keywords: host size preference ; parasitoid ; stored product ; maize ; biological control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé La première génération d'Anisopteromalus calandrae (Howard) récoltée dans du maïs stocké commercialement en Caroline du Sud fut exposée, dans du maïs écossé, à un mélange de jeunesSitophilus zeamais Motschulsky, de toutes tailles représentant une distribution d'âge uniforme. On a observé 87% de parasitisme sur les larves comportant un tunnel de 0,9 à 1,8 mm et 6% sur les prépupes et pupes pour cette distribution d'âge. Le taux de préférence était le plus élevé pour les grosses larves-hôte (1,6 mm de diamètre), moyen pour les autres larves de 0,9 à 1,8 mm, et le plus bas pour les pupes et les petites larves. On a discuté de la sélectivité des hôtes en utilisant les paramètres de Chesson (1983): préférence, αi, probabilité de parasitisme, Pi, et index d'électivité ɛi.
    Notes: Abstract First generationAnisopteromalus calandrae (Howard) collected from commercial stored maize in South Carolina were exposed to a mixture of all sizes of immatureSitophilus zeamais Motschulsky, representative of a uniform age distribution, in shelled maize. Eighty-seven percent of parasitism is expected on larvae with tunnel diameters of 0.9 to 1.8 mm and 6% on prepupae and pupae, given this host-size distribution. Preference was greatest for large host larvae (1.6 mm diameter), intermediate for other larvae in the range 0.9 to 1.8 mm, and least for pupae and small larvae. Host-stage preference is discussed with respect to Chesson's (1983) parameters for preference, αi, probability of parasitism, Pi, and electivity index, ɛi.
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  • 77
    ISSN: 1573-8248
    Keywords: Aphidius polygonaphis ; Illinoia liriodendri ; Liriodendron tulipifera ; tuliptree aphid ; biological control ; hyperparasitoids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé Un recensement du cortège parasitaire deIllinoia liriodendri (Monell) effectué en Californie du nord de 1988 à 1990 a révélé la présence de 12 espèces de parasitoïdes primaires et de 14 espèces d'hyperparasitoïdes. Le plus abondant des parasitoïdes primaires,Aphidius polygonaphis (Fitch), importé dans les années 1970, est à présent établi dans toute la région. Sont signalés pour la première fois associés àI. liriodendri les parasitoïdes primaires suivants:A. ervi Haliday,A. avenaphis (Fitch),Praon occidentale Baker,P. unicum Smith,Diaeretiella rapae M'Intosh,Lysiphlebus testaceipes (Cresson), etMonoctonus nervosus (Haliday) [tous Hymenoptera: Braconidae: Aphidiinae] etAphelinus sp. nr.asychis Walker [Hymenoptera: Aphelinidae]. Les hyperparasitoïdes les plus abondants sontPachyneuron aphidis (Bouché) etAsaphes californicus Girault [tous deux Hymenoptera: Pteromalidae]Pachyneuron californicum Girault etCoruna clavata Walker [Hymenoptera: Pteromalidae] sont signalés pour la première fois comme hyperparasitoïdes sur Aphidiinae et Aphelinidae spp. pour le premier, et surAphelinus sp. pour le second.
    Notes: Abstract A survey of the parasitoids ofIllinoia liriodendri (Monell) in northern California conducted from 1988–1990 revealed the presence of 12 primary and 14 hyper-parasitoid species. The most common primary parasitoid wasAphidius polygonaphis (Fitch), which was imported from the eastern United States in the 1970's and is now established throughout the area. New host records were noted forA. ervi Haliday,A. avenaphis (Fitch), Praon occidentale Baker,P. unicum Smith,Diaeretiella rapae M'Intosh,Lysiphlebus testaceipes (Cresson), andMonoctonus nervosus (Haliday) (all Hymenoptera: Braconidae: Aphidiinae), andAphelinus sp. nr.asychis Walker (Hymenoptera: Aphelinidae). The most common hyperparasitoid species werePachyneuron aphidis (Bouché) andAsaphes californicus Girault (both Hymenoptera: Pteromalidae). New hyperparasitoid host records were noted forPachyneuron californicum Girault on Aphidiine and Aphelinidae spp. andCoruna clavata Walker (Hymenoptera: Pteromalidae) onAphelinus sp.
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  • 78
    ISSN: 1573-8248
    Keywords: Mamestra brassicae ; Chrysodeixis chalcites ; parasitoid ; sweet pepper ; biological control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Eulophus pennicornis, a hymenopteran parasitoid of several Lepidoptera, was found onMamestra brassicae in a commercial sweet pepper crop in 1990 in Belgium. The rearing of the parasitoid and some additional data on biology are described.
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  • 79
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    BioControl 38 (1993), S. 89-100 
    ISSN: 1573-8248
    Keywords: parasitoid ; biological control ; release of beneficial arthropods
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé Entre 1975 et 1982, l'Institut de Lutte biologique “Israël Cohen” a mis en place un programme de lutte biologique contre la cochenille noire de l'olivierSaissetia oleae (Olivier) (Hom.: Coccidae). Au cours de cette période, 17 espèces d'ennemis naturels furent introduites en Israël, et les populations du ravageur retombèrent à un niveau acceptable. Le principal parasitoïde responsable de cette réduction a étéMetaphycus bartletii A. & M. (Hym.: Encyrtidae). Cet article expose le programme et apporte en outre quelques données sur la biologie des parasitoïdes introduits.
    Notes: Abstract During the years 1975–1982, the “Israel Cohen” Inst. for Biological Control conducted a biological control project, against the black scale,Saissetia oleae (Olivier) (Homoptera: Coccidae). Seventeen species of natural enemies were introduced into Israel during that period, and their action reduced the populations of the pest to an acceptable level. The major parasitoid responsible for that transition wasMetaphycus bartletti Annecke & Mynhardt (Hymenoptera: Encyrtidae). This article describes the project and introduces some notes on the biology of the introduced parasitoids.
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  • 80
    ISSN: 1573-8248
    Keywords: biological control ; parasitism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Two indigenous species ofTrichogramma were reared from natural populations of the blackheaded fireworm,Rhopobota naevana (Hübner) infesting cranberries in British Columbia, Canada. One was identified asTrichogramma sp. nr.sibericum Sorokina and the other wasTrichogramma minutum Riley. Percentage of parasitized hosts increased during the season in an abandoned field, but decreased in a commercial field where pesticides were used. The potential ofTrichogramma as a biological control agent against the fireworm is discussed.
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  • 81
    ISSN: 1573-8248
    Keywords: biological control ; Parabemisia myricae ; Eretmocerus debachi ; Citrus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé L'aleurodeParabemisia myricae (Kuwana) est l'un des plus sérieux ravageurs des vergers de citrus dans la région métiterranéenne de l'est de la Turquie. En 1986, un parasitoïde spécifique deP. myricae, l'aphelinideEretmocerus debachi Rose et Rosen, était introduit de Californie en Turquie et lâché dans les vergers de Citrus le long de la côte méditerranéenne orientale. Au cours des années suivantes, les populations deP. myricae étaient rapidement tombées d'environ 17 aleurodes au stade immature par feuille à moins de 0,1 par feuille dans tous les vergers de citrus où les parasitoïdes ont été lâchés. De plus,E. debachi a montré une bonne capacité de dispersion et s'est bien adapté aux conditions climatiques de la région orientale. Depuis l'installation réussie deE. debachi, l'aleurode n'est plus un ravageur dangereux et il est difficile de trouver des individus non parasités dans la région méditerranéenne de l'est de la Turquie.
    Notes: Abstract The whitefly,Parabemisia myricae (Kuwana) is one of the most serious citrus pests in the Eastern Mediterranean region of Turkey. In 1986, a host-specific parasitoid ofP. myricae, the aphelinidEretmocerus debachi Rose and Rosen, was imported from California to Turkey and released into citrus orchards along the Eastern Mediterranean coast. In the following yearsP. myricae-populations were rapidly reduced from about 17 whitefly-immature stages per leaf to less than 0.1 stages per leaf in all citrus orchards where the parasitoids were released. Furthermore,E. debachi was shown to be a good disperser and it is well adapted to the climatic conditions in the Eastern Mediterranean region. Since the successful colonization ofE. debachi, the whitefly is no longer a serious pest and it is difficult to find unparasitized individuals in the Eastern Mediterranean region of Turkey.
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  • 82
    ISSN: 1573-8248
    Keywords: sex ratio ; parasitoid ; biological control ; Australia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé Dans un verger de pommier à Armidale, sur les plateaux du nord de la Nouvelle Galles du Sud la sex ratio des populations d'Aphelinus mali, un endoparasitoïde d'Eriosoma lanigerum varie de 0,51 (pourcentage de mâles) pour de faibles densités de l'hôte à des proportions favorables aux femelles pour des densités d'hôtes élevées (pourcentage de mâles compris entre 0,35 et 0,39). Cette variation dans la sex ratio est apparemment due à des différences dans l'attribution d'une descendance mâle ou femelle en fonction de la taille de l'hôte. dans la nature,A. mali parasite le puceron du pommier à tous les stades de son développement (les 4 stades larvaires et l'adulte). D'après le modèle du régime optimal de Hughes (1979), l'acceptation de l'hôte sous toutes ses formes semble être la meilleure stratégie. Cependant, il permet à l'hôte de continuer son développement (dans le cas d'un stade larvaire) ou de se reproduire (au stade adulte) jusqu'à la momification. Aucune mortalité n'est observée en laboratoire lorsque l'hôte est parasité au 1° ou au 2° stade larvaire. Des momies de petite taille récoltées sur le terrain présentent une sex ratio favorable aux mâles alors que des momies de grande taille produisent surtout des femelles. En laboratoire, la descendance issue des hôtes de faible taille (du 1° au 3° stade) présente une sex ratio qui n'est pas significativement différente de 0,5 alors que la descendance issue des hôtes de grande taille (3° et 4° stade) montre une sex ratio favorable aux femelles. Pendant l'hiver (juin–août) et le début du printemps (septembre–octobre), c'est-à-dire à la période où la population hôte dans le verger est constituée principalement de larves, le parasitoïde tend à produire autant de mâles que de femelles. En revanche, aux pics de densité de population, en été et en automne (décembre à mai) lorsque des hôtes de grande taille sont disponibles, la sex ratio est favorable aux femelles. La taille de l'hôte,E. lanigerum et celle deA. mali, sont donc des éléments importants pour la dynamique des relations hôtes-parasitoïdes.
    Notes: Abstract In an apple orchard at Armidale, the Northern Tablelands of NSW, population sex ratios ofAphelinus mali (Haldeman), an endoparasitoid of the woolly apple aphid,Eriosoma lanigerum (Hausmann) varied from 0.51 (proportion of males) at low host densities to female-biased at high host densities (proportion of males ranged from 0.35–0.39). This shift in sex ratio seems to be caused by the differences in allocation of sons and daughters to hosts of different sizes. In the fieldA. mali parasitizes all life stages (four nymphal instars and adult) of the woolly aphid upon encountering. According to Hughes'(1979) optimal diet model, such general host acceptance seems to be the best strategy. However, it allows the host nymphs or adults to continue to develop or reproduce until about to mummify (pupate). No mortality was observed when first or second-instar hosts were parasitized in the laboratory. Field collected small mummified hosts yielded male-biased sex ratios whereas large mummified hosts produced mainly females. In the laboratory, progeny from smaller hosts (first to third-instars) produced sex ratios which were not significantly different from 0.5 whereas progeny from larger hosts (third and fourth-instars) produced female-biased sex ratio. During winter (June–August) and early spring (September–October) when the host populations in the orchard were predominantly nymphs, the parasitoid tended to allocate equal resources to male and female offspring. In contrast, at peak population densities in summer and autumn (December–May) when larger hosts were available, the sex ratios were female-biased. The host size ofE. lanigerum andA. mali is, therefore, an important component in the dynamics of host-parasitoid interactions.
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  • 83
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    BioControl 38 (1993), S. 537-539 
    ISSN: 1573-8248
    Keywords: Life cycle ; host specificity ; Pachycerus cordiger ; Heliotropium europaeum ; Boraginaceae ; biological control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The univoltine weevilPachycerus cordiger Germar (=P. scabrosus Brullé) completes its life cycle on species of Boraginaceae, it is found from western Europe to the Middle East. In southern France, adultP. cordiger were collected feeding on the leaves ofHeliotropium europaeum L.,Echium vulgare L. andCynoglossum creticum Miller, whereas larvae were found feeding externally on the roots of the three plant species from within an earthen cell. BecauseP. cordiger is considered too much of a generalist to be released in Australia, work on the weevil as a potential biological control agent ofH. europaeum has been stopped.
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  • 84
    ISSN: 1573-8248
    Keywords: Plutella xylostella ; Diadegma semiclausum ; biological control ; biology ; temperature effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé Des études en laboratoires ont été menées sur certains aspects de la biologie deDiadegma semiclausum Hellén, parasitoïde larvaire d'un ravageur des crucifères,Plutella xylostella (L.). Entre 15 et 35°C, plus la température est élevée, plus courte est la durée du développement des stades larvaires et adulte. L'éclosion et l'émergence des adultes est élevée entre 15 et 30°C mais elle est significativement réduite à 35°C. Plus la température est haute, plus la proportion de mâles est grande. Le seuil théorique de développement est de 5,74°C pour les œufs; 3,80°C pour les larves, 5,91°C pour les nymphes et 6,60°C pour les adultes. La ponte deD. semiclausum dans les larves des trois premiers stades deP. xylostella produit plus de parasitoïdes mâles que de femelles mais la ponte dans le 4e stade produit significativement plus de femelles que de mâles. Les parasites adultes ont tendance à émerger de la nymphe entre 6 h et 9 h bien que quelques individus sortent à d'autres moments de la photophase. La longévité des adultes et la production d'œufs augmentent quand on fournit aux adultes de la nourriture (miel) par rapport à l'absence de nourriture ou la fourniture d'eau seule. Des parasites adultes survivent et pondent pendant 28 jours lorsqu'on les nourrit mais seulement pendant 3 jours lorsqu'ils sont privés de nourriture.
    Notes: Abstract Laboratory studies were conducted on certain aspects of biology ofDiadegma semiclausum Hellén, a larval parasite of a crucifer pest,Plutella xylostella (L.). Within the range of 15°C to 35°C, the higher temperature, the shorter was the duration of larval and adult stages. Egg hatching and adult emergence were high at 15°C to 30°C but were significantly reduced at 35°C. The higher the temperature, the higher was the proportion of males produced. Temperature threshold was 5.74°C for eggs, 3.80°C for larvae, 5.91°C for pupae and 6.60°C for adults.D. semiclausum oviposition in the first threeP. xylostella larval instars produced more parasite males than females but oviposition in the fourth instar produced significantly more females than males. Parasite adults tended to emerge from their pupae from 06∶00 to 09∶00 hours although some emerged at other hours during the photophase. Adult longevity and production of eggs increased when adults were provided with a food source (honey) compared with no food or provision of water alone. Parasite adults survived and laid eggs for 28 days when provided with food but for only three days when deprived of food.
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  • 85
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    Nutrient cycling in agroecosystems 32 (1992), S. 223-227 
    ISSN: 1573-0867
    Keywords: Soil testing ; phosphorus ; relative yield
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A greenhouse experiment, with Okra (Abelmoschus esculentus L.) as the test crop, was conducted on twenty-one soils ranging in Olsen's extractable phosphorus from 1.8 to 15.5µg Pg−1 soil. The experiment was conducted at Punjab Agricultural University, Ludhiana, India. The soils were nonsaline with pH ranging from 7.7 to 8.6. A critical level of 2.55µg Pg−1 soil was predicted by Cate and Nelson's (1971) statistical procedure. Because of a wide range in relative yields, this value did not accurately predict response to applied P. An approach to compute minimum response to applied fertilizer, which is likely to be obtained at a particular Olsen P level, has been presented. It involves calculation of lower 60 percent confidence limits for relative yield and fitting loge-linear regression to the transformed data. The regression was tested on a published data set and was found to hold well.
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  • 86
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    Nutrient cycling in agroecosystems 32 (1992), S. 259-267 
    ISSN: 1573-0867
    Keywords: Nitrogen ; phosphorus ; timber increment ; fertilization ; Pinus radiata
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Two trials inPinus radiata growing on different sites in N.S.W. allowed consideration of fertilizer applications after 2nd or 3rd thinning. The trials included factorial applications of N and P at a single thinning intensity plus a further treatment which allowed assessment of different thinning intensities. The most significant growth responses were obtained by application of N and P in combination. The largest response (additional productivity compared with the unfertilized control) occurred 4 years after application and after 7 years there was no additional absolute response for either of the two sites. The largest fertilizer response was 70 m3 ha−1 over 7 years on one site and 36 m3 ha−1 on the other, indicating differences in absolute responses between sites. It was concluded that in planning treatments the most responsive sites near the end of the rotation should be selected to maximise economic returns. Foliage analyses indicated differences between sites at the commencement of the study. It was concluded that either a single year of foliage analyses at study commencement is of value, or sampling every year of the study should be used to analyse responses, but a single year of analysis during or at the end of the study would not be of value.
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  • 87
    ISSN: 1573-8469
    Keywords: Liriomyza bryoniae ; Diglyphus isaea ; simulation model ; biological control ; parasitoid-host interactions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A deterministic model was developed to simulate population growth of the agromyzid flyLiriomyza bryoniae and the parasitoidDiglyphus isaea. The model has two driving variables, ambient temperature and leaf nitrogen content of the tomato plant. Results of a glasshouse experiment were used to validate the model. The timing of successive generations of leafminers was simulated accurately over four generations. Population growth of leafminers was correctly simulated during the first two generations, but overestimated in the third generation. Mortality of leafminers due to parasitism was overestimated in the first generation after introduction of parasitoids: 73% instead of the observed 30%. A nearly 100% mortality of leafminers was correctly simulated in the second generation after introduction of parasitoids. Sensitivity analysis was performed for three types of variables: (1) driving variables, temperature and leaf nitrogen content; (2) parasitoid traits, searching efficiency and allocation of attacks to host feeding and oviposition, and (3) introduction strategies for biological control, timing, number of releases and number of parasitoids per release. Population growth was sensitive to temperature, leaf nitrogen content, searching efficiency of parasitoids and numbers of parasitoids released.
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  • 88
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    European journal of plant pathology 98 (1992), S. 37-45 
    ISSN: 1573-8469
    Keywords: cultural measures ; chemical control ; biological control ; resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Conventional ways to control aphid vectors on potato crops rely essentially on cultural and chemical methods. The extensive use of insecticides, too often applied regardless of real needs and consequences, has resulted in more and more failures in both controlling aphids and virus spread. This paper stresses the need to introduce more rationale in the operation of existing methods by improving the efficiency of some of them like forecasting systems, to assess the potential of others like fertilization and semiochemicals and to put most efforts on resistant cultivars so that integrated pest management can be operated in the near future.
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  • 89
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    European journal of plant pathology 98 (1992), S. 77-80 
    ISSN: 1573-8469
    Keywords: biological control ; hyperparasites ; cell wall degradation ; enzymes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Some fungal species isolated from other fungi were tested for their capacity to degrade chitin, cellulose and laminarin. Only three entomophagous fungi degraded native chitin. However colloidal chitin was degraded by all fungi tested except four. Cellulolytic activity was mainly found in fungi with a poor performance against cucumber powdery mildew. This suggests that the capacity to produce cellulase is not important for successful mycoparasitic activity against cucumber powdery mildew. A good correlation was found between the capacity to degrade laminarin and the mycoparasitic activity of the fungi that were investigated.
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  • 90
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    Plant and soil 142 (1992), S. 157-166 
    ISSN: 1573-5036
    Keywords: Acacia ; Eucalyptus regnans ; decomposition ; litterfall ; nitrogen ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The N and P contents of the litter layer and the return of these nutrients in litterfall were measured in seven stands of Mountain Ash (Eucalyptus regnans) ranging in age from 5 years to about 250 years. Both annual litterfall and nutrient return were correlated with stand basal area and were high compared with other productive eucalypt forests. In contrast, the fall of dead eucalypt leaves was constant with stand age, demonstrating that sites are fully occupied at an early age. Similarly, amounts of N and P in total leaf fall (overstorey plus understorey) were constant with stand age, except for low amounts in the stand aged 40 years where Acacia spp., important fixers of atmospheric N, were not prevalent. The decomposition constant (k) of organic matter in the litter layer decreased with stand age, from 0.31 year-1 at age 5 years to 0.23 year-1 at age 250 years. These constants also applied to N and P, indicating a tight coupling between organic matter decomposition and release of these nutrients from litter. The litter layer released about 30 kg ha-1 of N at age 5 years, and about 70 kg ha-1 at age 80 years. These results are discussed in relation to growth of Mountain Ash following fire, and the subsequent retention and accumulation of N during stand development.
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  • 91
    ISSN: 1573-5036
    Keywords: biological control ; Sclerotium rolfsii ; furfural ; slow-release N fertilizer compounds ; soil microflora
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Populations of microorganisms from soil treated with guanidine thiocyanate, guanylurea sulfate, thiourea, or furfural were compared with those of untreated soil. The materials effected quantitative and/or qualitative changes in composition of the soil microflora depending on the compound used. Guanidine thiocyanate (Gt) significantly (p≤0.05) increased total fungal populations relative to populations of other treatments. Populations of Penicillium purpurogenum were markedly higher in Gt-treated soil. Gt also increased total bacterial populations, and was the only compound that increased actinomycete populations. The relative percentage of Trichoderma harzianum was significantly higher in soil treated with thiourea than in the other treatments. Furfural increased the percentage of P. purpurogenum with respect to total fungi, and was as effective as guanylurea sulfate in increasing chitinolytic bacteria and those in the Pseudomonas cepacia-group. Thiourea most effectively promoted proliferation of coryneform bacteria. Chitinolytic fungi increased synergistically when Gt and guanylurea sulfate were applied in combination.
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  • 92
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    Plant and soil 145 (1992), S. 45-50 
    ISSN: 1573-5036
    Keywords: acidity ; manganese ; pH ; phosphorus ; soil solution wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A pot experiment was carried out in order to test the hypothesis that manganese nutrition of wheat was dependent on the phosphorus status of soil as well as on its pH and manganese status. An arable mineral soil whose lime and phosphorus status had been massively adjusted more than 18 years previously was compared with identical soil not so adjusted. Wheat plants were grown to maturity in these soils. Analyses were carried out on both soil and plant samples at intervals. Data for soil pH, soil solution concentrations of manganese and phosphorus, plant dry weight and tissue concentrations of manganese and phosphorus are presented. Concentrations of manganese were depressed in leaf tissue of plants from limed soils and also in high phosphorus soils. The depressed values for limed treatments were explained in terms of depressed soil solution manganese concentrations resulting from elevated pH. The results for high phosphorus soils could not be related to soil solution composition. It was suggested that high soil phosphorus resulted in elevated plant phosphorus which interfered in the uptake and/or translocation of manganese.
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  • 93
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    Plant and soil 146 (1992), S. 163-168 
    ISSN: 1573-5036
    Keywords: genetic variability ; NIR ; ploidy ; phosphorus ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract More efficient utilization of phosphorus by wheat plants is needed to extend the useful life of the phosphate reserves in the world, to reduce the cost of producing crops, and to improve the value of the grain and the straw produced. In this paper definitions of efficient use of phosphorus by wheat are reviewed, genotypic variation in phosphorus efficiency is reported, some consequences of breeding for greater efficiency are discussed, and ways to select more efficient genotypes are suggested.
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  • 94
    ISSN: 1573-5036
    Keywords: critical concentration ; deficiency ; diagnosis ; growth rate ; lettuce ; luxury consumption ; nitrogen ; nitrate ; nutrient requirement ; petiole sap ; phosphorus ; phosphate ; potassium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A method is described for determining the way in which growth rate varies with plant nutrient concentration using a simple nutrient interruption technique incorporating only 2 treatments. The method involves measuring the changes in growth and nutrient composition of otherwise well-nourished plants after the supply of one particular nutrient has been withheld. Critical concentrations are estimated from the relationship between the growth rate (expressed as a fraction of that for control plants of the same size which remained well-nourished throughout) and the concentration of the growth-limiting nutrient in the plants as deficiency developed. Trials of the method using young lettuce plants showed that shoot growth rate was directly proportional to total N (nitrate plus organic N) concentration, and linearly or near-linearly related to K and P concentration over a wide range; the corresponding relationship for nitrate was strongly curvi-linear. Critical concentrations (corresponding to a 10% reduction in growth rate) determined from these results were similar to critical values calculated from models derived from field data, but were generally higher than published estimates of critical concentration (based on reductions in shoot weight) for plants of a similar size. Reasons for these discrepancies are discussed. Nitrate, phosphate or potassium concentrations in sap from individual leaf petioles were highly sensitive to changes in shoot growth rate as deficiency developed, with the slope of the relationships varying with leaf position, due to differences both in their initial concentration and in the rates at which they were utilized in individual leaves. Each nutrient was always depleted more quickly in younger leaves than in older ones, providing earlier evidence of deficiency for diagnostic purposes. Although the plants were capable of accumulating nitrate, phosphate and potassium well in excess of that needed for optimum dry matter production during periods of adequate supply, the rate of mobilization of these reserves was insufficient to prevent reductions in growth rate as the plants became deficient. This brings into question the validity of the conventional concept that luxury consumption provides a store of nutrients which are freely available for use in times of shortage. The implications of these results for the use of plant analysis for assessing plant nutrient status are discussed.
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  • 95
    ISSN: 1573-5036
    Keywords: antagonism ; bacterization ; biological control ; sheath blight
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Fluorescent and nonfluorescent strains of bacteria isolated from rice rhizospheres on the International Rice Research Institute (IRRI) farm were evaluated for in vitro antibiosis towards the sheath blight (ShB) pathogen Rhizoctonia solani, and for suppression of ShB in detached rice leaves. Efficient strains were located on the basis of consistent performance in two laboratory tests. Among nine efficient strains, 3 strains were identified as Pseudomonas fluorescens, 5 strains were tentatively identified as Bacillus spp. and one strain was identified as Enterobacter. In three greenhouse tests lowland rice soils with optimum pH for rice growth (pH 5.5–6.5), acidic pH (pH 5.0) and boron toxicity were found more suitable for biological control of ShB and, less frequently, also yield increases than were alkaline (pH 6.9) and zinc-deficient soils. Bacterial treatments afforded significant ShB reductions in 3 field experiments, but no significant yield increases resulted. In direct-seeded rice best performances by bacterial treatments in terms of ShB suppression were 66 and 98% during DS 1988 and WS 1988, respectively, which were comparable to or better than the performance of validamycin (a fungicide routinely used for ShB control) which afforded 42 and 63% disease suppression, respectively, in the same experiments. Although bacterial treatments caused ShB reductions both in direct-seeded and transplanted rice crops, disease control was more pronounced in direct-seeded than in transplanted crops. These results indicate that carefully selected strains of bacterial antagonists have the potential for ShB suppression in rice at least in areas where direct-seeding is practised.
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  • 96
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    Plant and soil 145 (1992), S. 65-70 
    ISSN: 1573-5036
    Keywords: calcifuge plants ; phosphorus ; deficient absorption ; Deschampsia flexuosa ; Jasione montana ; Rumex acetosella ; Silene rupestris
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Germination, seedling establishment and growth of calcifuge plants in Swedish limestone soils of Archean and Ordovician age were studied. As previously demonstrated for Viscaria vulgaris, establishment of Rumex acetosella and Silene rupestris did not succeed unless CaHPO4 (at the rate of 10 mmol dm-3 of soil) was supplied. Growth of Deschampsia flexuosa was enhanced by phosphate addition, whereas establishment success of Jasione montana was poor, regardless of phosphate treatment. Establishment and growth in an acidic gneiss soil, used as a reference for the species studied, was good. Total, total inorganic, exchangeable, and soil solution P were considered in all soils and treatments. It is proposed that the calcifuge behaviour of plants is quite often caused by inability to solubilize the native phosphate of limestone soils.
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  • 97
    ISSN: 1573-5036
    Keywords: cultivars ; grains ; maize ; nitrogen ; phosphorus ; potassium ; tropical climate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract An earlier study revealed considerable genotypic variation in grain N, P and K concentrations (GNC, GPC and GKC, respectively) in tropical maize. The expression of varietal differences in GNC, GPC and GKC, however, may depend on environmental conditions such as the N status of the soil. Two tropical maize hybrids (Suwan 2301 and CP 1) with comparable yielding capacity, but contrasting GNCs, GPCs and GKCs, were therefore grown at four levels of N in a field experiment at Farm Suwan (Thailand, latitude 14.5°N). Suwan 2301 exhibited a higher GNC than did CP 1 at all rates of N, but large differences in GPC and GKC were found only at high N fertilization. This was obviously due to individual grain yield responses of the cultivars to increasing rates of N fertilizer, demonstrating that grain nutrient concentrations are, at least in part, functions of the amount of grain carbohydrates which dilute a genetically and environmentally fixed amount of grain P and K. As compared to Suwan 2301, CP 1 accumulated less N, P and K in the grains at almost all levels of N fertilization, confirming our hypothesis that the cultivation of maize genotypes with low grain mineral nutrient concentrations may help third-world cash-crop farmers to reduce the need for scarce and costly mineral fertilizers. This finding has to be verified at reduced availability of soil −P, −K, and water.
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  • 98
    ISSN: 1573-515X
    Keywords: nitrogen fixation ; phosphorus ; internal loading ; water hyacinth ; floodplain ; Paraná ; flood-pulse hypothesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Some aspects of nutrient status and dynamics prevailing during low and high water conditions in the fringing floodplain ponds of the Paraná River dominated by the floating macrophyte Eichhornia crassipes are described. During summertime low water conditions, low DIN:DRP ratios (0.16–1.0) and low DIN (0.5–4.8 μmol.liter−1) in the root-zone of the floating meadows suggest that macrophyte growth is limited by nitrogen. DRP concentrations appear to be controlled more by abiotic sorption-dissolution than by biological reactions. Preflood nutrient fluxes from the sediments, as estimated from porewater profiles, show that a minimum of 1.19 and 0.38 mmol.m−2.d−1 of DIN and DRP were regenerated from the sediments, respectively. Heterotrophic N2 fixation is primarily associated with decaying litter (0.4 to 3.2 μmolN2.g−1.d−1). Nutrient recycling from sediments and meadow-litter, and heterotrophic N2 fixation (1.4 mmolN.m−2.d−1) appear sufficient to sustain high floating macrophyte productivity for long periods of time, without invoking large inputs from the river. The high water and early isolation periods are characterized by a very dynamic behavior of DIN, reflecting marked imbalances between N supply and demand by the biota. After hydrologic isolation of the ponds, DIN rapidly decreases to undetectable levels and stays low for the following 3 weeks, presumably as a result of high demand by phytoplankton and sediment bacteria. DIN increases again to high values 3–8 weeks after the flood, following the re-establishment of NH4 + fluxes from the sediments. Compared to DIN, DRP concentrations remain relatively high and change little during and after the flood. Because of their small amplitude and short duration, floods do not appear to stimulate floating macrophyte production in the Paraná.
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    Biogeochemistry 18 (1992), S. 19-35 
    ISSN: 1573-515X
    Keywords: Dinitrogen fixation ; nitrogen ; phosphorus ; competition ; legumes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract An analysis of data compiled from the literature confirms a strong inverse relationship between annual rates of nitrogen fixation and the soil nitrogen content in agricultural and pastoral ecosystems. However, this inverse relationship is strongly modified by the rate of application of phosphorus fertilizer, which strongly influences the activities of both symbiotic and non-symbiotic nitrogen fixing organisms. In the case of symbiotic legumes, the response of N-fixation to N and P is in part a result of changes in legume dominance within the plant community. These results, as well as supporting data presented from a review of experiments on nitrogen fixation in a variety of other terrestrial and aquatic ecosystems, provide important support for the hypothesis that phosphorus availability is a key regulator of nitrogen biogeochemistry.
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  • 100
    ISSN: 1573-515X
    Keywords: nitrogen ; phosphorus ; soil fertility ; tropical forest
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract We measured concentrations of soil nutrients (0–15 and 30–35 cm depths) before and after the dry season in control and dry-season irrigated plots of mature tropical moist forest on Barro Colorado Island (BCI) in central Panama to determine how soil moisture affects availability of plant nutrients. Dry-season irrigation (January through April in 1986, 1987, and 1988) enhanced gravimetric soil water contents to wet-season levels (ca. 400 g kg−1 but did not cause leaching beyond 0.8 m depth in the soil. Irrigation increased concentrations of exchangeable base cations (Ca2+, Mg2+, K+, Na+), but it had little effect on concentrations of inorganic N (NH4 +C, NO3 − and S (SO4 2−). These BCI soils had particularly low concentrations of extractable P especially at the end of the dry season in April, and concentrations increased in response to irrigation and the onset of the rainy season. We also measured the response of soil processes (nitrification and S mineralization) to irrigation and found that they responded positively to increased soil moisture in laboratory incubations, but irrigation had little effect on rates in the field. Other processes (plant uptake, soil organic matter dynamics) must compensate in the field and keep soil nutrient concentrations at relatively low levels.
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