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  • Articles  (76)
  • Nitrogen  (39)
  • Nitrogen fixation  (37)
  • 1980-1984  (76)
  • 1945-1949
  • 1984  (51)
  • 1983  (25)
  • Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition  (76)
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  • Articles  (76)
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  • 1980-1984  (76)
  • 1945-1949
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Nutrient cycling in agroecosystems 5 (1984), S. 355-369 
    ISSN: 1573-0867
    Keywords: Nitrogen ; fertilizer ; dynamic model ; sugar beet
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A concise model is described for calculating day-to-day increments in nitrogen uptake and dry matter of crops grown with different levels of N-fertilizer. Inputs are the initial distribution of inorganic-N down the profile, the maximum yield, the maximum depth of rooting, and the mineralization rate. The validity of the model was tested against measurements of the %N and total dry weights of storage roots and foliage in nine N-fertilizer trials with sugar beet, six of which included both irrigated and unirrigated treatments. Agreement between the model and experiment was good except in one experiment severely attacked by virus yellows. Simulation studies with the model indicated that no simple correlation would be expected between N fertilizer requirement and any single indicator of N availability for crops grown under a wide range of conditions in the UK.
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  • 2
    ISSN: 1573-5036
    Keywords: Clover ; Fertilizer ; Lotus ; Nitrogen fertilizer ; Nitrogen fixation ; Nitrogen source ; Nodulation ; Trifolium repens
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Studies under growth cabinet conditions investigated the effect of source and concentration of nitrogen and timing of nitrogen application on the growth and nitrogen fixation byLotus pedunculatus cv. Maku andTrifolium repens cv. S184. KNO3, NaNO3 and NH4NO3 were added at transplanting at the following rates: 3.33, 7.78 and 13.33 mg N/plant. KNO3 was added at 3.33 and 7.78 mg N/plant at 0, 6, 12, 18, 24 or 30 days after transplanting. Lotus shoot weight increased with all increasing nitrogen sources but clover only responded to KNO3 and NaNO3. The root weight of both species increased with increasing KNO3 and NH4NO3. The percentage increase in lotus and clover shoot growth was greater than that of root growth when KNO3 was added within a week of transplanting. Increases in growth by both species resulted from added nitrogen except with lotus when NaNO3 was applied where increased nitrogen fixation also contributed to increased growth. Weight and number of effective nodules on both species were increased with 3.33 mg N per plant as KNO3 but nitrogen fixation was not affected. Addition of 13.33 mg N as NaNO3 reduced weight and number of effective nodules in both species and also nitrogen fixation by lotus. KNO3 increased growth and nodulation of both species when applied within one week after transplanting. Nodulated lotus plants responded to KNO3 by increasing growth but not nodulation. KNO3 appeared to affect infection and development of nodules on lotus and may affect the growth of existing nodules on clover.
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  • 3
    ISSN: 1573-5036
    Keywords: Neem cake coated urea ; Nitrogen ; Phosphorus ; Potassium ; Rice ; Rice-wheat ; Sulphur coated urea ; Urea ; Urea briquette
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Removal of NPK in the rice-wheat double cropping system was studied in a field experiment conducted for two crop years (1977–79) at the Indian Agricultural Research Institute, New Delhi. The double cropping system producing 8×103 kg/ha/yr grain (4.5×103 kg rice and 3.5×103 kg wheat) removed 166 kg N, 35 kg P and 174 kg K per hectare per year. Thus the rice-wheat double cropping system heavily depletes the soils of their NPK content and calls for balanced fertilization for continued high production. NPK removal was higher when a 135-day duration rice variety was grown than when a 105-day duration variety was grown, because the former resulted in overall (rice + wheat) more grains and straw. Similarly grain and straw yield and NPK removal was more with transplanted rice than when sprouted rice seeds were sown on puddled seedbed; the latter method was in turn superior to direct drilling. Use of urea briquette, neem cake coated urea and sulphur coated urea gave higher yields and resulted in removal of more NPK than prilled urea.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Plant and soil 71 (1983), S. 415-431 
    ISSN: 1573-5036
    Keywords: Carbon allocation ; Light Mycorrhizas ; Nitrogen ; Phosphorus ; Photosynthesis ; Pinus contorta ; Pinus taeda ; Pisolithus tinctorius ; Respiration ; Source-sink ; Suillus granulatus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Studies examined net photosynthesis (Pn) and dry matter production of mycorrhizal and nonmycorrhizalPinus taeda at 6 intervals over a 10-month period. Pn rates of mycorrhizal plants were consistently greater than nonmycorrhizal plants, and at 10 months were 2.1-fold greater. Partitioning of current photosynthate was examined by pulse-labelling with14CO2 at each of the six time intervals. Mycorrhizal plants assimilated more14CO2, allocated a greater percentage of assimilated14C to the root systems, and lost a greater percentage of14C by root respiration than did nonmycorrhizal plants. At 10 months, the quantity of14CO2 respired by roots per unit root weight was 3.6-fold greater by mycorrhizal than nonmycorrhizal plants. Although the stimulation of photosynthesis and translocation of current photosynthate to the root system by mycorrhiza formation was consistent with the source-sink concept of sink demand, foliar N and P concentrations were also greater in mycorrhizal plants. Further studies examined Pn and dry matter production ofPinus contorta in response to various combinations of N fertilization (3, 62, 248 ppm), irradiance and mycorrhizal fungi inoculation. At 16 weeks of age, 6 weeks following inoculation with eitherPisolithus tinctorius orSuillus granulatus, Pn rates and biomass were significantly greater in mycorrhizal than nonmycorrhizal plants. Mycorrhizal plants had significantly greater foliar %P, but not %N, than did nonmycorrhizal plants. Fertilization with 62 ppm N resulted in greater mycorrhiza formation than either 3 or 248 ppm. Increased irradiance resulted in increased mycorrhiza formation.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Plant and soil 72 (1983), S. 321-334 
    ISSN: 1573-5036
    Keywords: Leguminous plants ; Nitrogen fixation ; Protein ; Seed ; Yield
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Mineral nitrogen did not increase grain yield and seed protein levels ofVicia faba L. andLupinus luteus L. in field trials and pot experiments. Fixed N2 was substituted by mineral nitrogen in these cases because of inhibition of N2 fixation by mineral nitrogen. Contrary to these results mineral nitrogen increased grain yields and seed protein amounts ofLupinus albus L.,Pisum sativum L., andGlycine max. (L.) Merr. The nitrogen effect was caused at an early stage by saving energy due to inhibition of N2 fixation (measurement of gas exchange by means of IRGA). In case of the N application after flowering grain, yields and seed protein levels increased because the mineral N was an additional nitrogen source for plants. At this stage the plants had ceased fixing atmospheric nitrogen. The high sink activity of growing fruits induced a lack of assimilates in nodules (determined by means of14CO2 application). The N effect was therefore the consequence of the lower assimilate pool for supplying root nodules in these plants in comparison withVicia faba L. andLupinus luteus L. Hence it follows that response to mineral nitrogen can be a criterion for discovering more effective Rhizobium-host combinations.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Plant and soil 73 (1983), S. 431-434 
    ISSN: 1573-5036
    Keywords: Nitrogen fixation ; 15N2 diffusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Summary The kinetic of15N2 diffusion has been measured in a system similar to that for the estimation of N2 fixation in plant microorganism associations cultivated in soil. The15N2 enrichment of the soil atmosphere reached an homogenous value one hour after injection of15N2 and is identical to that obtained by calculation, indicating that no adsorption occurs in the soil particles.
    Notes: Résumé La cinétique de diffusion du15N2 est mesurée sur un système identique à ceux pouvant être utilisés pour la mesure de fixation de l'azote chez les associations plantes-microorganismes cultivées sur sol. L'enrichissement homogène de l'atmosphère du sol est obtenu une heure environ après l'injection de15N2 et correspond à l'enrichissement calculé, ce qui indique qu'aucune adsorption n'a lieu dans les particules du sol.
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  • 7
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    Plant and soil 75 (1983), S. 131-138 
    ISSN: 1573-5036
    Keywords: Hydrogen inhibition ; Nitrogen fixation ; Peas ; Relative efficiency ; Rhizobium leguminosarum ; Root nodules
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Experiments were performed to investigate the causes of low relative efficiency, RE, in legume root nodules. Nitrogen fixing activity and RE varied with time of incubation of nodules and with different temperatures and oxygen concentrations. The effects of nitrogen concentration and carbon dioxide concentration were also examined. In each case the RE was inversely related to nitrogen fixing activity; measured by acetylene reduction. Increasing the nitrogen concentration had no effect on either nitrogen fixing activity or RE. Experiments with isolated bacteroids gave higher RE values than the whole nodules from which they were isolated. All the results were consistent with hydrogen inhibition of nitrogenase within the nodule being the cause of low RE.
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  • 8
    Electronic Resource
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    Springer
    Plant and soil 75 (1983), S. 379-391 
    ISSN: 1573-5036
    Keywords: Crop development ; Grain yield ; Nitrogen ; Nitrogen dressing ; Nitrogen economy ; Nitrogen harvest-index ; Soil Wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Nitrogen exerts its influence on crop growth and grain yield in various ways. Early top dressings or a high level of soil nitrogen stimulate tiller formation and leaf growth, which results in an increase of shoot dry weight and leaf area index. Late top dressings promote the survival of ear-bearing tillers, grain set and leaf area duration. Nitrogen compounds for grain growth are mainly supplied by the vegetative aerial parts (65–80%); the remainder originating from uptake and relocation by the roots after anthesis. The proportion of the total amount of nitrogen present in the grains, the nitrogen harvest-index, centers around 0.78 under optimum conditions. The recommendations for nitrogen dressing are based on the amount of residual soil nitrogen and on the requirement of the crop in the given environment. Both components may vary considerably due to environmental constraints. Despite inaccuracies in the assessment of mineral nitrogen content of the soil and the predicted nitrogen requirement of the crop, the recommendations for splitting nitrogen dressing in winter wheat have considerably improved the efficient use of nitrogen fertilizer.
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  • 9
    ISSN: 1573-5036
    Keywords: Ammonium ; Barley ; Fertilizer ; Mineralization ; Nitrate ; Nitrogen ; Nitrogen-15
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Field experiments were carried out using15N-labelled calcium nitrate, to investigate the relative uptake by barley of fertilizer-N and soil-N. On imperfectly drained till soils uptake of soil-N increased with increasing rate of fertilizer, but remained constant on a brown sand, possibly due to more efficient root exploration in the latter soil. In four out of five seasons, late uptake of soil-derived N was a major feature, and uptake from ploughed soil as compared with uptake from direct-drilled soil was correlated with seasonal rainfall patterns. Significantly higher quantities of both fertilizer- and soil-derived N were taken up by winter barley than by spring barley, reflecting the longer growth period and higher dry matter yield from the former crop.
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  • 10
    Electronic Resource
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    Springer
    Plant and soil 76 (1984), S. 127-137 
    ISSN: 1573-5036
    Keywords: Adenylate pool ; Biomass volume ; CO2 evolution ; Chitin ; DNA ; Electron microscopy ; Enzymes ; Fluorescent antibody ; Fumigation-respiration ; Fungi Histochemistry ; Imunofluorecence ; Jones-Mollison technique ; Microcosms ; Monoclonal antibodies ; Nitrogen ; Nutrients ; Oxygen consumption ; Phosphorus ; Phytotoxins ; Plate counts ; Rhizobium ; Rhizosphere ; Sulphur ; Xenobiotics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary There is an immense literature on biological and biochemical analyses of soils. Such analyses have revealed the enormous richness of species in soil and their vast range of metabolic potentials and ecological diversity. Accordingly, the approaches used to investigate the soil biota and its biochemistry usually have to be modified or adapted depending upon the purpose of the investigation. Studies of micro-organisms in the soil environment, are complicated because microbial cells are commonly attached to surfaces where they live side-by-side with other populations in consortia usually containing different morphological and physiological types. Such assemblages of organisms cannot be described quantitatively using cultural techniques, such as plate counts, which underestimate both cell numbers and viable biomass. The development of more powerful observational and staining techniques has improved our knowledge of the diverse morphological and biochemical composition of soil micro-communities. Such findings have been amplified at a grosser level by laboratory studies with multi-component systems (microcosms) to mimic field situations and to assess the range of biochemical potentials of microbial consortia. But despite notable advances in analytical methods we are still, with a few exceptions, unable to detect or identify those microorganisms which carry out specific biochemical transformations or determine whether particular cells are alive, dormant or dead at the time of observation. Considerable work has been done to define some of the fundamental ecological attributes of microbial assemblages in soil. Productive work on the metabolic activities of the soil microbiota, specially geochemical transformations of C, N, S and P, has been under way for more than a century. But only in more recent years have more sensitive and reproducible analytical methods become available to measure viable biomass in soil. This will enable some insight to be gained into the role that microbial biomass plays as a labile source and sink for plant nutrients.
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  • 11
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    Springer
    Plant and soil 76 (1984), S. 213-226 
    ISSN: 1573-5036
    Keywords: Acetylene ; Arable crops ; Cultivation ; Denitrification ; Drainage ; Gas ; Chromatography ; Grassland ; Inorganic N fertilizer ; Irrigation ; Nitrogen ; Nitrous oxide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Recent denitrification research is reviewed to answer questions a) how much N is lost from the soil as N2 and N2O and b) how do agronomic practices affect this loss? The methods used to quantify denitrification are also discussed. Gaseous losses of inorganic N range between the equivalent of 0 to 20 per cent of the fertilizer N applied to arable soils and 0–7 per cent on grassland soils. Losses are greater on undrained land and also after using direct drilling to establish arable crops. Appendix 1 summarizes reported measurements of gaseous N losses.
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  • 12
    ISSN: 1573-5036
    Keywords: Carbon ; Concepts ; Cultivation effects ; Nitrogen ; Nitrogen-15 ; Organic matter models ; Particle size fractions ; Phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Changes in the composition of organo-mineral particle size fractions as a result of cultivation of a grassland soil are discussed with reference to models of soil organic matter formation and turnover. The data presented indicated that physically stabilized organic matter is an important reservoir, with an intermediate turnover time, which is responsible for nutrient supply in agricultural soils. Possible mechanisms of stabilization and mobilization of organic matter are presented in the light of the arrangement of organic and inorganic components of the soil.
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  • 13
    ISSN: 1573-5036
    Keywords: Actinorhizae ; Alnus nitrida ; Frankia ; Host-specificity ; Nitrogen fixation ; Root nodules
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Two different strains, An 1 and An 2, were obtained from root nodules ofAlnus nitida Endl., collected from one locality in the area of its natural habitat near Bahrin, District Swat, Pakistan. The light and electron microscopy of the isolates revealed the occurrence of septate and branched hyphae bearing sporangia and vesicles. The strains differed in their growth requirements, nitrogen-fixing ability and production of extracellular pigments, thus indicating the existence of more than oneFrankia strain in the same locality. In the absence of combined nitrogen in the medium strain An 1 formed vesicles and fixed N2 (up to 200 nmol C2H4. mg protein−1.h−1), while strain An 2 under the experimental conditions formed only few vesicles and fixed N2 at a very low rate (ca 10 nmol C2H4. mg protein−1 .h−1). The nitrogenase activity of strain An 1 was strongly affected by the O2 concentration.Frankia An 1 and An 2 were infective and effective onA. nitida andA. glutinosa but not onDatisca cannabina andElaeagnus umbellata. Both An 1 and An 2 strains were more infective and effective onA. glutinosa thanFrankia strains AvcIl and CpI1.
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  • 14
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    Plant and soil 77 (1984), S. 253-261 
    ISSN: 1573-5036
    Keywords: Acetylene reduction ; Beijerinckia ; Nitrogen fixation ; Paddy ; Phyllosphere ; Silicification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary An investigation was conducted to study the levels of nitrogen fixation on the leaf or sheath surfaces of four cultivars of paddy plants by using acetylene reduction technique. Varying levels of positive nitrogenase activity were observed on all the leaf surfaces. Sheath of IET 1991 cultivar showed a higher rate of fixation than the leaf surface. All the nitrogen-fixing organisms on the leaf or sheath surfaces belonged to the genus Beijerinckia. There was no correlation between the bacterial density and the level of fixation. Scanning electron microscopic data revealed that the upper surface of IET 1991 leaf was highly silicified and the microflora was either scanty or nil while the lower surface appeared quite different and harboured more micro-organisms. Similarly, the inner surface of sheath was devoid of silicification and showed the presence of micro-organisms.
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  • 15
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    Plant and soil 78 (1984), S. 29-43 
    ISSN: 1573-5036
    Keywords: Alnus glutinosa ; Endophyte ; Frankia ; Infectivity ; Nitrogen fixation ; Sporulation ; Variability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Frankia sp. LDAgpl, an isolate from spore positive nodules ofAlnus glutinosa, only slowly infects its host plant. Reisolates obtained from occasional nodules caused by infection with LDAgpl, are capable of infecting the alder much more rapidly. A variability analysis of LDAgpl has been performed to obtain more insight into the question whether these reisolates constitute a different genotype within LDAgpl and if the plant is exerting an influence during plant passage. High dilutions of mildly sonicatedFrankia suspensions were plated to obtain genetically homogeneous colonies. Clones thus generated showed differences in growth pattern, sporulation and C2H2-reduction on media containing propionic acid as sole C-source (P-medium). Differences in sporulation on P-medium indicate that LDAgpl was a highly heterogeneous strain. Comparisons of sporulation on several different media gave evidence that the differences in sporulation between LDAgpl clones are the result of differences in efficiency of propionic acid utilization. The differences observed between the reisolates and LDAgpl clones indicate that the reisolates constitute a different genotype, which could be selected for by the plant during the infection process. Comparison with similar changes in phenotype occuring in a spore negative type strain fromA. glutinosa is discussed.
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  • 16
    ISSN: 1573-5036
    Keywords: Actinorhizas ; Alnus nitida ; Amino acid composition ; Datisca cannabina ; Hydrogen uptake ; Inoculation ; Nitrogen fixation ; Root nodules
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The nodulation and the morphology and physiology of the nodules were studied onDatisca cannabina, a perennial herb from northern Pakistan andAlnus nitida, a nodulated tree in the same locality. Both species bear coralloid clusters of actinorhizal nodules. The main free amino acid inD. cannabina nodules was arginine while the predominant free amino acid inA. nitida nodules was citrulline. The infectivity of crushed nodules of both types of plants on their respective host was about 106 infective particles per gram of nodule fresh wt. In cross-inoculation experiments crushed nodule inoculum fromA. nitida failed to induce nodulation onD. cannabina seedlings but the crushed nodule inoculum fromD. cannabina caused low nodulation on seedlings ofA. nitida (103 infective particles. g. nodule fresh wt.). The activity of nitrogenase, hydrogenase and respiration (O2 uptake) were measured in detached nodules, nodule homogenates and the 20 μm residue and 20 μm filtrate preparations from the nodules of both species. Both species showed similar patterns of activities except that only the nodule homogenate and 20 μm residue preparations fromD. cannabina showed pronounced enhancement of the O2 uptake by succinate which was further stimulated by ADP. This has in part been explained by the presence of mitochondria in close connection with the endophyte.
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  • 17
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    Plant and soil 79 (1984), S. 227-234 
    ISSN: 1573-5036
    Keywords: Bacteria ; Inoculation ; Microorganisms ; Nitrogen fixation ; Phosphate solubilization ; Rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Inoculation effect ofA. chroococcum, P. striata andA. awamorii on yield and nutrients uptake in rice was studied under green house conditions. The organisms appreciably increased the yield and uptake of nutrients with or without chemical fertilizers. Phosphorussolubilizing microorganisms and a mixture of the three showed better response than the rest of the treatments among single and mixed culture inoculations respectively. Chemical fertilizers further improved the yield and nutrients uptake. The yield response remained unaffected by replacing superphosphate with rock phosphate and microbial inoculations.
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  • 18
    ISSN: 1573-5036
    Keywords: Mesquite ; Nitrogen fixation ; 15N natural abundance ; Nodule morphology ; Rhizobium bacteria ; Woody legumes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The relative nitrogen fixation efficiencies (RE 1-[H2 evolved÷C2H2 reduced]·100) of four mesquite (Prosopis glandulosa var.torreyana) rhizobia (Strains WR 1001, WR 1002, L5, L9) and a cowpea rhizobia (Strain 176A32) on mesquite were evaluated in a glasshouse experiment. Plant yield, shoot N accumulation, and the natural15N abundance (δ15N) of nodule tissue were determined. Strain WR 1002 failed to nodulate mesquite and strain L5 produced ineffective nodules. Among the three effective strains (WR 1001, L9, 176A32) the cowpea strain (176A32) and strain L9 had significantly higher RE than strain WR 1001. Differences in RE, however, were not accompanied by significantly higher plant yield and shoot N accumulation. The difference in15N abundance between foliar tissue and nodules (nodules minus leaves) was 0.47 δ15N for the ineffective L5 nodules, while for the effective WR 1001, L9, and 176A32 nodules, respectively, this difference was 8.35, 7.81, and 8.35 δ15N. This indicates a similar relationship between N2-fixing effectiveness and natural15N enrichment of nodules that was previously observed in soybeans (Glycine max, L. Merr.). Strains WR 1001 and L9 produced elongate, indeterminate nodules typical for mesquite. The ineffective L5 nodules had few infected cells and an abundance of cortical amyloplasts. Mesquite nodules produced by the cowpea strain were spherical and were somewhat more similar in internal morphology to determinate nodules typical of cowpea than indeterminate nodules normally associated with mesquite.
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  • 19
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    Plant and soil 79 (1984), S. 343-351 
    ISSN: 1573-5036
    Keywords: Alnus rubra ; Aluminum ; Annual returns ; Essential elements ; Litterfall ; Leaf litter ; Nitrogen ; Nutrients ; Red alder
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Litterfall was collected over 1 year from eight natural stands of red alder growing on different sites in western Washington. The stands occurred at various elevations and on different soils, and differed in age, basal area, and site index. Most litterfall was leaf litter (average 86 percent). Amounts of litterfall and leaf litter varied significantly (P〈0.05) among the sites. Average weights of litterfall and leaf litter in kg ha−1 yr−1, were 5150 and 4440, respectively. Weight of leaf litter was not significantly (P〈0.05) related to site index, stand age, or basal area. The sites varied significantly (P〈0.05) in concentrations of all elements determined in the leaf litter, except Zn. Average chemical concentrations were: N, 1.98 percent; P, 0.09 percent; K, 0.44 percent; Ca, 1.01 percent; Mg, 0.21 percent; S, 0.17 percent; SO4−S, nil; Fe, 324 ppm; Mn, 311 ppm; Zn, 53 ppm; Cu, 13 ppm; and Al, 281 ppm. There were significant correlations between some stand characteristics and concentrations of some elements, and among the different chemical components of the leaf litter. Important correlations were found between stand age and P concentration (r=−0.84,P〈0.01); weight of leaf litter and P concentration (r=0.74,P〈0.05); weight of leaf litter and K concentration (r=0.71,P〈0.05); concentrations of N and S (r=0.81,P〈0.05); and concentrations of Fe and Al (r=0.98,P〈0.01). Returns of the different elements to the soil by leaf litter varied among the different sites. Average nutrient and Al returns, in kg ha−1 yr−1, were: N, 82; Ca, 41; K, 19; Mg, 8; S, 7; P, 4; Fe, 1; Mn, 1; Al, 1; Zn, 0.2, and Cu, 〈0.1.
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  • 20
    ISSN: 1573-5036
    Keywords: Actinorhizae ; Datisca cannabina ; Frankia ; Nitrogen fixation ; Root nodules ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The fine structures of the microsymbiont inside the root nodules ofDatisca cannabina have been studied by light, by transmission- and by scanning-electron microscopy. The endophyte is prokaryotic and actinomycetal in nature. The hyphae are septate and branched, diameter 0.3–0.5 μm. The tips of hyphae are swollen to form electron-dense, clubshaped to filamentous vesicles, ranging in diameter: 0.4–1.4 μm. The endophyte penetrates through walls of the cortial cells. The infected zone is kidney shaped and confined to one side of the acentric stele. The orientation of infection is reversed from other actinorhizae exceptCoriaria. The hyphae are near the host cell wall and vesicles are directed towards the central vacuole. Vesicles are aseptate and no collapsing of the vesicle cell wall (void area) has been observed. Vesicle clusters structures are globular with an opening at one side of the cluster. The host cell is multinucleate or contains a lobed nucleus. Groups of mitochondria are located in between the hyphae, suggesting a strong association between the host and the endophyte for energy supply and amino acid production. The consequences of the inability to separate the mitochondria from the vesicle clusters in nodule homogenates in physiological studies have been discussed. Isolated vesicles clusters showed dehydrogenase activity, indicated by the presence of formazan crystals, after incubation with NADH and NBT. Strongest reducing activity was found within the vesicles. The possible role of filamentous vesicles in nitrogen fixation has been discussed.
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  • 21
    ISSN: 1573-5036
    Keywords: Acetylene reduction ; Actinomycete-nodulated ; Legume ; Lime ; Mine spoil ; Nitrogen fixation ; Reclamation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary An acid mine spoil in Southern Indiana was amended with lime (CaCO3) (0.0, 12.5, 25 and 39t/ha) and planted withElaegnus umbellata Thunb.,Alnus glutinosa Gaertn.,Robinia pseudoacacia L.,Robinia fertilis Ashe, ‘Arnot’,Myrica pensylvania Lois,Caragana arborescens L. andShepherdia argentea Nutt. Survival and soil data were collected periodically and plants were harvested 15 months after planting. Nodule and top dry weights were determined and acetylene reduction assays performed on the nodules. Addition of lime caused significant increases in pH, and 39 t/ha of lime were required to maintain a pH above 5.5. Survival of plant material was greatest at the highest lime addition, although response of individual species varied.Elaeagnus umbellata, R. pseudoacacia, R. fertilis ‘Arnot’, andA. glutinosa appeared more tolerant of the harsh conditions. OnlyC. arborescens showed a linear increase in top dry weight due to lime addition.Alnus glutinosa andS. argentea achieved statistically the same growth regardless of pH, andR. fertilis ‘Arnot’ andE. umbellata did not increase in top dry weight above an addition of 25 t/ha.Robinia pseudoacacia achieved maximum top dry weight at 25 t/ha, whereasM. pensylvanica growth declined with increasing pH. Nodule dry weights increased with increasing pH; however,S. argentea showed greater nodule dry weights at lower lime levels. Acetylene reduction rates increased with lime addition.Elaegnus umbellata did not respond above 25 t/ha lime, whereasA. glutinosa did not show an increase until this point.
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  • 22
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    Plant and soil 74 (1983), S. 395-406 
    ISSN: 1573-5036
    Keywords: Fix− mutants ; Fix+ revertants ; Macroptilium lathyroides ; Nitrogen fixation ; Rhizobium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Eight ineffective mutant strains were isolated from N-methyl-N'-nitro-N-nitrosoguanidine mutagenized cultures of cowpea Rhizobium strain 32H1. Strains CR1, CR2, CR3, CR4, CR5 and CR6 induced more, but smaller, nodules than the wild type. With the exception of strain CR2, these mutant strains reduced less than 1% of the amount of acetylene reduced by the wild type, in both the free-living and symbiotic assays. Strain CR2 reduced acetylene in the free-living assay but not in the symbiotic assay. Strains CR7 and CR8 responded variably (5–20% of the wild type) in free-living and symbiotic acetylene reduction assays. Nodules also varied from small white to normal-sized pink nodules. The phenotypic characteristics of the mutant strains were consistant with all leguminous plants tested and were stable upon reisolation from nodules. Fully effective revertants were selected from 4 of the ineffective mutant strains by the use of the leguminous plant,Macroptilium lathyroides. Serology, patterns of resistance to anti-bacterial agents, phage-typing, and antibiotic resistance markers were used to confirm strain identification.
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  • 23
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    Plant and soil 71 (1983), S. 49-53 
    ISSN: 1573-5036
    Keywords: Fertiliser ; Fine roots ; Mycorrhizas ; Nitrogen ; Picea sitchensis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Fertilisation with N alters the numbers, biomass and seasonal pattern of activity of fine roots and mycorrhizas in spruce humus. Production and mortality decrease, and longevity increases. Fertilisation reduces mycorrhizal infection, alters the relative proportions of mycorrhizal types and permits the appearance of new types.
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  • 24
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    Plant and soil 72 (1983), S. 95-105 
    ISSN: 1573-5036
    Keywords: Acetylene reduction ; Inga jinicuil ; Nitrogen fixation ; Nodulation ; Nodule biomass ; Nutrients ; Shading ; Tropics ; Woody legume
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A pot experiment was conducted to assess the effects of different fertilizers and soil shading on nodulation and acetylene reduction ofInga jinicuil seedlings. Initially, seedlings produced maximum nodule biomass when grown with high levels of phosphorus but reduced the most acetylene under intermediate phosphorus fertilization. These response differences, however, gradually diminished with age, being negligible when the seedlings were a year old. Nitrogen fertilization inhibited nodulation and acetylene reduction throughout the experiment. Potassium did not significantly affect nodulation, but low levels of potassium stimulated, and high levels inhibited acetylene reduction activity relative to unfertilized control plants. Neither magnesium nor molybdenum affected nodulation or acetylene reduction. Soil shading resulted in decreased nodule biomass and less nitrogen-fixing activity during summer months. However, the data suggest that shading may favour nitrogen fixation in colder periods by moderating soil temperatures. These results confirm findings from an earlier field study and show that nodulation and nitrogen-fixing activity by leguminous trees is influenced by the types and amounts of nutrients supplied. This suggests that the quantity of nitrogen fixed by leguminous shade trees in coffee plantations may be amenable to manipulation through simple management techniques.
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  • 25
    ISSN: 1573-5036
    Keywords: Boron ; Calcium ; Copper ; Genotypic differences ; Iron ; Magnesium ; Manganese ; Mineral nutrition ; Molybdenum ; Nitrogen ; Phosphorus ; Plant adaptation ; Plant breeding ; Potassium ; Zinc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Plant genotypes differ in their uptake, translocation, accumulation, and use of mineral elements. Examples of genotype differences to iron, nitrogen, phosphorus, potassium, calcium, magnesium, manganese, boron, copper, zinc, and molybdenum are discussed. Current knowledge is sufficient to indicate that many crop plants can be improved for the efficient use of mineral elements and better adaptation to mineral stress conditions.
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  • 26
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    Plant and soil 71 (1983), S. 371-380 
    ISSN: 1573-5036
    Keywords: Apple ; Calcium ; Copper ; Iron ; Irradiance ; Magnesium ; Manganese ; Nitrogen ; Nutrient uptake rate ; Phosphorus ; Potassium ; Scion effects ; Season ; Source of nitrogen ; Temperature ; Tissue nutrient level ; Zinc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The rates of uptake of nutrients from solution by apple roots were measured (a) in a root laboratory, using intact roots of mature trees growing under field conditions and (b) in controlled environment using young trees. Maximum nitrate inflows into Discovery/M.9 roots under field conditions were only slightly lower than those into roots of the same genotype in controlled environment, but up to 80 times lower than those into roots of Worcester Pearmain seedlings. At any given external P concentration, P inflows into roots of field-grown trees were about 2.5-times lower than those into the roots of young trees in controlled environment. Nitrate inflows were constant above a solution concentration of 20 mmol m−3 in both field-grown and small trees. In both cases, phosphate inflows increased linearly with solution concentration up to 10 mmol m−3. Among the various plant and environmental factors influencing nutrient uptake characteristics of apple roots were: the scion genotype, tissue nutrient levels, root origin, the form in which N is supplied, level of irradiance of the shoot, root temperature and the season of the year. The effects of these factors are illustrated with examples.
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  • 27
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    Plant and soil 71 (1983), S. 401-413 
    ISSN: 1573-5036
    Keywords: Carbohydrates ; Cultural factors ; Environment ; Fruit trees ; Nitrogen ; Reserves ; Seasonal pattern
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary In trees, nutrient reserves built up in the previous year are of primary importance for early spring growth. Despite the relatively great importance of roots for nutrient storage, the root system should not be regarded as a special storage organ. Quantitatively, carbohydrates predominate in these reserves, but qualitatively N and other minerals are of more than minor significance. In roots carbohydrates are usually stored in insoluble form, mainly as starch; sorbitol is the predominant soluble compound in apple and peach. For nitrogen reserves, the soluble form predominates in roots, especially arginine in apple and peach, followed by asparagine. The level of reserves usually becomes maximal early in the winter. During leafing-out the reserves are drawn on until, later in the season, the supply of newly produced or absorbed nutrients exceeds the demand and replenishment occurs. The initial carbohydrate reserves do not determine the amount of new growth, whereas reserve nitrogen is of decisive importance for shoot growth vigour. Environmental factors such as light intensity and temperature affect the level of carbohydrates in roots; the concentration can be reduced by defoliation and summer pruning and increased by ample supply of nitrogen fertilizer in the autumn. The main cultural factors that influence nitrogen reserves are the amount and the time of nitrogen fertilization.
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  • 28
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    Plant and soil 72 (1983), S. 351-364 
    ISSN: 1573-5036
    Keywords: Acid soils ; Cation exchange capacity ; Fertilizer use ; Nitrogen ; Phaseolus vulgaris ; Phosphorus ; Selection ; Soil stresses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Genetic effects are obtainable for any aspect of transport, accumulation, and efficiency of nutrient use by plants, and for virtually any element. Some of the important characters are: tolerance to acid soils (18% of soils or 2.4 billion ha), tolerance to high pH induced Fe-chlorosis, and tolerance to salinity (about 1,000 m ha). Genotypes which made better use of N and P would be the means of saving fertilizers, especially important to developing countries. A 10% economy of fertilizer use represents a minimum world saving of US$6 billion annually. Phaseolus vulgaris is taken as a model to show that although we know quite a lot about the extent of its nutritional variation, e.g. adaptability to acid soils, and the crop's utilization of N and P, we are handicapped in exploiting this because of lack of genetic information. This in turn depends on knowledge of specific mechanisms, and investigating these must be a priority.
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  • 29
    ISSN: 1573-5036
    Keywords: Corn ; Nitrogen ; Phosphorus ; Potassium ; Sugarbeet ; Sunflower
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A three-year experiment was conducted in natural conditions on chernozem soil to examine the efficiency of nitrogen, phosphorus, and potassium use by corn (C4 type), sunflower and sugarbeet (C3 type) grown in optimum conditions of mineral nutrition (N100P100K100 kg/ha). Plant materials were analysed for the concentration of nitrogen, phosphorus, and potassium and dry matter mass per individual plant parts and the whole plant. Leaves of different age, of all three plant species, were analysed to find eventual differences in the efficiency of use of nitrogen, phosphorus, and potassium in the synthesis of organic matter depending on leaf age. It was found that corn had the lowest concentration of the elements studied but the highest dry matter mass. In other words, corn was more efficient than sunflower or sugarbeet in the use of these elements for the synthesis of an organic matter unit. Such results were arrived at in both sets of analyses, i.e., the analyses of leaves performed in the course of ontogenetic plant development as well as the analyses of leaves of different age.
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  • 30
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    Plant and soil 76 (1984), S. 3-21 
    ISSN: 1573-5036
    Keywords: Agriculture ; Barley ; Budgets ; Fauna ; Fertilizers ; Global cycles ; Lucerne ; Meadow fescue ; Microorganisms ; Nitrogen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Agro-ecosystems have developed from mixed- and multiple-cropping systems with relatively closed N cycles to intensively managed monocultures with large N inputs in the form of commercial fertilizers. Cultivation of increasingly larger areas of land has resulted in substantial losses of soil organic matter and N. Also, the move from slash and burn agriculture to intensively ploughed systems has resulted in losses through increased erosion. The use of N fertilizers has increased rapidly toca. 60 Tg N yr−1 (1980/81), which is equivalent to at least 40% of the N fixed biologically in all terrestrial systems and 36% more than is fixed in all croplands. On a global scale, the major losses of N from agro-ecosystems are estimated to be: harvest, 30 Tg; leaching, 2 Tg; erosion, 2–20 Tg; denitrification 1–44 Tg; and ammonia volatilization, 13–23 Tg. However, the data base is very crude and several estimates may be wrong by as much as one order of magnitude. Additions of N fertilizers have both direct and indirect effects on soil microorganisms. The possible importance of such effects is briefly discussed and a specific example is given on long-term effects on soil microbial biomass and nitrification rates in 27-year-old cropping systems with different N additions: (i) 0 kg N ha−1 yr−1, (ii) 80 kg N ha−1 yr−1, (iii) farmyard manureca. 80 kg N ha−1 yr−1. Few detailed N budgets exist for agro-ecosystems, despite its major importance as a limiting plant nutrient and the large losses of N from such systems. In conclusion, preliminary nitrogen budgets for four cropping systems (barley receiving 0 or 120 kg N ha−1 yr−1; meadow fescue ley with 200 kg N ha−1 yr−1 and a lucerne ley) are presented, with special attention to N flow through the soil organisms.
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    Plant and soil 75 (1983), S. 309-342 
    ISSN: 1573-5036
    Keywords: Acetylene reduction ; Amino-acid composition ; Chromosome number ; Cross-inoculation ; Growth various substrates ; Medium composition ; Nitrogen fixation ; Parasponia parviflora ; Root nodule ; Temperate Rhizobium species
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Cross-inoculation experiments withParasponia parviflora plants and a large number of Rhizobium strains isolated from legumes, mainly of temperate origin, showed that strains ofRhizobium trifolii andR. lupini could produce root nodulation in Parasponia. Root nodulation was also obtained with some tropical Rhizobium isolates such as those from Arachis and Albizzia, but not withRhizobium japonicum strains. In addition, strains ofR. leguminosarum, R. phaseoli andR. meliloti produced abnormal root nodules or pseudo-root nodules in Parasponia seedlings. All root nodules induced in Parasponia by foreign Rhizobium species lacked, however, nitrogenase activity. Testing the reverse combination Parasponia-Rhizobium on legumes yielded with regard to root nodulation negative results, except withVigna sinensis and twoMacroptilium species (M. atropurpureum andM. lathyroides). The root nodules produced in the latter legumes showed nitrogenase activity.Trema cannabina seedlings inoculated with Parasponia-Rhizobium invariably did not produce root nodules. The feasibility of Parasponia to accept foreign rhizobia bacteria or to produce pseudo-nodulation is probably genetically determined. In a karyological study it was shown thatParasponia parviflora had the chromosome number 2n=20. Growth experiments revealed thatP. parviflora can be cultivated in water culture, perlite and in soil (pot) culture. It can also be grown in agar tubes, although growth under these conditions is sometimes rather variable. Nitrogenase (C2H2) tests showed that water-culture root nodules were 5–10 times less active than those from perlite culture, soil or agar tubes. On the whole, nitrogenase activity of root nodules grown on the various substrates and receiving different treatments, was rather variable.Vigna sinensis plants inoculated with Parasponia-Rhizobium showed on basis of fresh nodule weight a 3–4 times higher nitrogenase activity as compared with the same strain on Parasponia. However, as shown by acetylene reduction tests of nodule slices, the main activity of mature Parasponia root nodules is situated in the apical part of the root nodule. On fresh weight basis the nitrogenase activity of this nodule section is of the same order as that of leguminous root nodules. Intact Parasponia plants showed higher nitrogenase activities than excised root nodules. The maximal nitrogen fixation rate ofParasponia parviflora plants was 20–25 μmol. C2H4·g−1 fresh weight nodule tissue.h−1, which value is comparable to that of legumes and higher than estimates obtained by Parasponia in the field. No decrease of the nitrogen-fixation rate was observed in Parasponia plants tested in a diurnal cycle during the 12-hours dark period. Amino-acid analyses of Parasponia root nodules showed large quantities of aspartic acid, asparagine, glutamic acid and glutamine suggesting a role of these amino acids in the nitrogen fixation or transport processes. In contrast to actinorhizal root nodules Parasponia root nodules do not contain citrulline. The latter amino acid was, however, found—although in rather low concentration—inVigna sinensis andMacroptilium atropurpureum nodules obtained withParasponia-Rhizobium.
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  • 32
    ISSN: 1573-5036
    Keywords: Genetic control ; Nitrogen fixation ; Pisum sativum L. ; Rhizobium Maternal effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary In pea cv. Afghanistan a recessive gene sym 6 prevents the full expression of nitrogenase activity in root nodules, induced byRhizobium leguminosarum strain F 13. In contrast, nitrogenase activity is fully expressed in pea cv. Iran. A comparison of the reciprocal hybrids of these two plants showed that the size of the plant was determined by the mother plant (maternal effect). Therefore the shoot weight and the total amount of nitrogen fixed are not suitable as parameters for a genetic analysis. The % nitrogen of the shoot and the specific activity of the nodules per gram of nodules are more reliable, but for practical purposes the specific activity of the nodules expressed per gram of shoot tissue can be used.
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  • 33
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    Plant and soil 76 (1984), S. 67-73 
    ISSN: 1573-5036
    Keywords: Maize ; Nitrogen ; Nitrogen uptake ; Tillage ; Zea mays L
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Nitrogen (N) accumulation data from a replicated field study were fitted to a tanh (time) function and the derivate obtained to determine relative maximum rates of accumulation by maize. Both positive and negative effects of tillage on N accumulation rates were observed. Most of the N accumulation occurred over a 30-day period and time of N accumulation was not affected by tillage. Tilled profiles tend to contain greater NO3−N, greater aeration, and lower moisture contents than untilled profiles, and these characteristics interact to affect plant N accumulation.
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  • 34
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    Plant and soil 77 (1984), S. 3-14 
    ISSN: 1573-5036
    Keywords: Asian-type soybean ; Fast-growingRhizobium japonicum ; Glycine max ; Nitrogen fixation ; Rhizobium japonicum ; Rhizobium physiology ; Root nodule
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Physiological and symbiotic characteristics were identified in fast-growing (FG)Rhizobium japonicum. Carbon nutritional patterns linked these rhizobia to other FG rhizobia. They were able to use hexoses, pentoses, disaccharides, trioses, and organic acids for growth, but they were unable to use dulcitol or citrate. These rhizobia produced acid with all carbon sources except intermediates of the Krebs cycle. FGR. japonicum showed no vitamin requirements and were tolerant to 1% NaCl but not to 2%. They nodulated cowpea, pigeon pea, and mung bean but not peanut. Effective, nitrogen-fixing symbioses were observed only with cowpea and pigeon pea. In addition, FGR. japonicum formed effective symbioses with Asian-type soybeans. We concluded that although the physiological characteristics of FGR. japonicum were similar to other FG rhizobia, their symbiotic properties were similar to slow-growing rhizobia of the cowpea miscellany.
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  • 35
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    Plant and soil 77 (1984), S. 73-86 
    ISSN: 1573-5036
    Keywords: Fertiliser ; Foliar analysis ; Nitrogen ; Phosphorus ; Pinus radiata ; Potassium ; Soil organic matter ; Steenbjerg effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Copper deficiency inPinus radiata in Gippsland, Victoria was found to be associated with acid, organic-rich sandy podzols. A trial designed to find a Cu supplement for P and NPK fertilisation on these soils showed significant growth in stem-length following Cu-solution treatment in the nursery, and Cu fertiliser applied in the field up to at least 13.5 kg Cu ha−1. The Steenbjerg effect was evident in foliar concentrations of nutrients following fertilisation; this makes diagnosis from foliar analysis difficult. Foliar Cu∶N ratios proved a more sensitive indicator of Cu fertiliser treatment than either Cu or N alone. Two phases of seasonal drainage and podzol development were identified in the experiment. Trees growing on the better-drained, more acid soil with a high content of organic matter responded better to Cu fertiliser.
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  • 36
    ISSN: 1573-5036
    Keywords: Dehydrogenase ; Electron transport system ; Nitrogen ; Oxygen pH ; Substrate ; Temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Dehydrogenase activity was measured in a sandy loam soil under a variety of incubation conditions using the reduction of 2-(p-iodophenyl-3-(p-nitrophenyl)-5-phenyl tetrazolium chloride (INT) to iodonitrotetrazolium formazan (INT-formazan). There was a high positive correlation between dehydrogenase activity and substrate concentration, incubation temperature, and soil pH. Dehydrogenase activity also displayed a high negative correlation with O2 concentrations. Ammonium sulfate at concentrations from 40 to 120 μg/g soil had no significant effect on dehydrogenase activity. However, at concentrations of 160 and 200 μg/g, dehydrogenase activity was significantly reduced. Potassium nitrate at concentrations ranging from 40 to 200 μg/g had no significant effect on soil dehydrogenase activity, whereas sodium nitrite significantly inhibited activity at concentrations of 120 and 160 μg/g soil.
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  • 37
    ISSN: 1573-5036
    Keywords: Actinorhizal plants ; Bacterial isolation techniques ; Frankia ; Nitrogen fixation ; Root nodules ; Soil ; Sucrose density fractionation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The isolation and pure culture of the symbiotic nitrogen-fixing frankiae has always been difficult. In the past the isolation of these actinomycetes directly from soil samples has proven impossible and isolations from root nodules of many genera has been only poorly successful. We report here a modified sucrose fractionation procedure which increased the success of isolations from root nodules and which permitted the isolation ofFrankia directly from soil samples. Crushed nodule suspensions or soil suspensions were incubated briefly in 0.7% phenol (carbolic acid) just before application to a sucrose density gradient. This phenol incubation decreased the number of contaminating eubacteria and fungi but more importantly increased the number ofFrankia developing on the isolation plates. If the phenol incubation was used solely without sucrose fractionation noFrankia were isolated, suggesting the death of the organisms due to phenol toxicity. The use of selective nitrogen-deficient media proved important for the isolation of frankiae from soils.
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  • 38
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    Plant and soil 78 (1984), S. 105-128 
    ISSN: 1573-5036
    Keywords: Cytology of root nodules ; Dryas drummondii ; Frankia ; Geographic distribution ; Nitrogen fixation ; Rubus ellipticus ; Ultrastructure of endophyte
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Root nodules ofDryas drummondii are of the coralloid type (Alnus type). The endophyte is present in the middle cortical cells of the root-nodule tissue. Transmission electron micrographs revealed an actinorhizal endophyte with septate hyphae and non-septate spherical or ovoid vesicles. Vesicles always possess at the base a septum; septa formation in the endophyte is always associated with the presence of mesosomes. Branching of the endophyte is not necessarily correlated with septum formation. Hyphal structures are more prominent in the apical part of the root nodule and vesicles are more numerous in a broad zone below this. In the middle and towards the base of the root nodule the endophytic structures appear in a stage of disintegration. Vesicles appear in a broad region near the periphery of the host cell and regularly show no strict orientation towards the host-cell wall. In the center of the host cells only hyphae occur. In the intercellular spaces between the host cells theFrankia endophyte produces spore-like structures although the outline of the sporangia is often faint. The coralloid root ofRubus ellipticus shows characteristically a basal rootlet initiated below the dichotomous branching of the nodular lobes, but extending beyond the root nodule. The endophyte is only present in the outer cortex of the root nodule in a 1–2 cell wide layer. This endophytic layer is bounded, internally as well as externally, with a 4–5 cell wide layer of tannin-filled host cells. The implications of this situation are discussed. Tannin-filled cells occur regularly inRubus species and their arrangement has been used for taxonomic purposes within the genus. TheRubus endophyte is aFrankia species with septate hyphae and distinctly septate spherical vesicles. The ultrastructure of the vesicles of theRubus endophyte is very similar to that of theAlnus endophyte.
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  • 39
    ISSN: 1573-5036
    Keywords: Ammonium sulfate ; Nitrification ; Nitrogen ; Slow-release fertilizers ; Sulfur-coated urea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary We have compared sulfur-coated urea granules (SCU) with ammonium sulfate granules (AS) in regard to nitrogen (N) release, diffusion, nitrification and the effect of irrigation. In the experiments plastic containers were filled with six layers of soil, separated from each other by fine nylon cloths. The fertilizer granules were placed between the two central layers, and irrigation was simulated by application of tap water to the uppermost layer. Nitrogen release from the SCU was slow, and after three months, 29.5% of the applied N remained in the granules. At the end of the experiment there was a deficit of 37.1% N in the case of the AS granules, while there was virtually none with the SCU. Throughout the experiment, N from SCU remained at a relatively even level, while 95% of the N applied as AS had disappeared after irrigation. Nitrification was rapid in both cases.
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  • 40
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    Plant and soil 74 (1983), S. 437-450 
    ISSN: 1573-5036
    Keywords: Burning controlled ; Calcium ; Carbon ; CEC ; Eucalyptus ; Magnesium ; Nitrogen ; N. mineralisation ; Potassium ; Rainforest
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In mixed eucalypt/rainforest in southern Tasmania, samples of surface soil 0 to 2 cm, 2 to 5 cm, and 5 to 10 cm were taken from a clear-felled coupe before and after burning in 1982, from a similar coupe after burning in 1979, and from an uncut area adjacent to each coupe. Factors compared were bulk density; total organic C, N, P, Ca, Mg, and K; pH; exchangeable Ca, Mg, and K; cation exchange capacity; extractable P; and N-mineralisation rates. The effect of burning was found to be restricted mainly to the upper 2 cm of soil. The combustion of organic matter caused losses of 7360 kg organic C and 211 kg N/ha; 348 kg Ca and 282 kg Mg and 151 kg K/ha were added to the soil in ash. Burning caused significant increases in pH, exchangeable Ca, Mg, and K, and in extractable P; cation exchange capacity was reduced. In the 6 months after burning only K was leached from the upper 2 cm of soil. Equilibrium levels of NH4−N increased initially after the fire, but between 6 and 18 months, equilibrium levels and rate of production of NH4−N during anaerobic incubation in soil of burned coupes differed little from that in adjacent uncut forest. Rates of production of NO3−N during aerobic incubation were very low throughout the period of study. It is concluded that for soils developed on dolerite in mixed eucalypt/rainforest, a single regeneration burn probably improves the nutritional status of the soil. Nutrients lost from the area as particulate ash are in quantities that will probably be replaced in rainfall in 15 to 20 years.
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    Plant and soil 70 (1983), S. 133-140 
    ISSN: 1573-5036
    Keywords: Glycine max L. Merr ; Nitrogen ; Soybean ; Sulphur deficiency ; Vertisols
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Some soil and plant test methods were evaluated for predicting response of soybean crop (Glycine max (L.) Merr.) to S application in vertisols. Morgan's reagent, 500 ppm P containing Ca(H2PO4)2.H2O and KH2PO4 solutions, 0.5N NH4OAc+0.25N HOAc and 0.15% CaCl2 were found to be suitable extractants for measuring available soil S. The critical limits of extractable S were 9.0 ppm by Morgan's reagent, 10.0 ppm by phosphate solutions, 8.0 ppm by 0.5N NH4OAc +0.25N HOAc and 14.0 ppm by 0.15% CaCl2. Morgan's reagent was regarded as superior to other soil test methods in view of its high relationship with S uptake by plants, A values and relative yield. Critical S concentration in soybean plants varied with age. It was 0.15% and 0.185% for 36 and 60 days old plants, respectively. The critical N/S ratio on the other hand appeared to be constant at about 16.5 during vegetative growth period. Constancy of critical N/S ratio in plants was attributed to the near constancy of N/S ratio in plant proteins. There was highly significant relationship between response of soybean to S and to N, supporting the conclusion of some earlier workers that any soil showing large responses to N may not be supplying adequate S from the mineralization of soil organic matter.
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  • 42
    ISSN: 1573-5036
    Keywords: Acetylene reduction ; Glycine max L. ; Nitrogen fixation ; Soybean
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A system for employing open-ended root chambers to measurein situ acetylene reduction rates under field conditions is described. Gas mixtures containing about 2 mbar acetylene were continuously flowed through the chambers providing a continuous record of acetylene reduction. These chambers have been used to measure acetylene reduction rates of soybeans during three growing seasons. The system has proved to be reliable with a high degree of precision. The large amount of plant-to-plant variability observed in N2 fixation research has been confirmed by the data collected with this system. However, such variability in physiological studies can be reduced by using a non-destructive system to compare the response of an individual plant with its rates before treatment.
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  • 43
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    Plant and soil 70 (1983), S. 391-402 
    ISSN: 1573-5036
    Keywords: Intercropping Lupins ; Lupinus albus ; Manganese ; Nitrogen ; Phosphorus ; Triticum aestivum ; Wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Significant interactions between wheat and lupins occur below ground and wheat intercropped with lupins has access to a larger pool of available P, Mn and N than has wheat grown in monoculture. This suggests that the wheat is able to take up nutrients produced or made available by lupins grown in association with it.
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  • 44
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    Plant and soil 73 (1983), S. 117-128 
    ISSN: 1573-5036
    Keywords: Light quality ; Nitrogen fixation ; Trifolium repens ; White clover
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The possibilities of using light quality treatments to gain an understanding of the mechanisms controlling the allocation of photosynthate for symbiotic nitrogen fixation were studied. White clover (Trifolium repens) plants were grown at the same photon irradiance in red, blue and green light treatments. Growth, nodulation and the carbon/nitrogen economies of the plants were measured. Both photosynthetic rates per unit leaf area and shoot-root ratios were affected by the treatments. However, the carbon/nitrogen economies of the plants and the fraction of the total plant weight allocated to nodule growth were unaffected.
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  • 45
    ISSN: 1573-5036
    Keywords: Barley ; Cultivars ; Early vigour ; Glasshouse ; Hordeum vulgare L. ; Nitrogen ; Seed
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Variation in the nitrogen content of seed of six barley cultivars was brought about by growing parent plants at four nitrogen levels. Shoot dry weight of plants grown for 23 days from these seeds was generally enhanced by an increase in seed nitrogen content. The most responsive cultivar was a primitive type of barley from Ethiopia. Cultivars with a longer breeding history were less responsive. Risø 1508 apparently had physiological and biochemical limitations in responding to extra seed nitrogen. In the barley cultivars studied extra seed nitrogen seems to supplement, rather than substitute for, nitrogen fertilizer in the seed bed.
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  • 46
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    Plant and soil 73 (1983), S. 151-153 
    ISSN: 1573-5036
    Keywords: Acetylene reduction ; Beijerinckia ; C3 and C4 plants ; Nitrogen fixation ; Phyllosphere ; Wettability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Nitrogen fixation on leaf surfaces of sugarcane, sorghum, ragi, bamboo and mulberry plants was determined by using acetylene reduction assay. The data revealed varying levels of positive nitrogenase activity on the surfaces. Beijerinckia was observed to be the predominant diazotroph on the leaves. No correlation between fixation rates and C3 or C4 plant species was discerned. The possiblity of improving phyllosphere nitrogen fixation has been discussed in light of the above observations.
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  • 47
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    Plant and soil 73 (1983), S. 299-305 
    ISSN: 1573-5036
    Keywords: Nitrogen fixation ; Rhizobium trifolii populations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The effectiveness ofRhizobium trifolii isolates from five locations in southern Britain representing contrasting soil types has been examined with five white clover varieties. The average effectiveness of Rhizobium isolates varied considerably as did the average productivity of plant varieties. The largest differences were, however, associated with Rhizobium population × plant variety interactions. These were often large enough to reverse relative yield differences between white clover varieties. The implications of these results for improving clover productivity in nitrogen fixation are discussed.
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  • 48
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    Plant and soil 76 (1984), S. 165-173 
    ISSN: 1573-5036
    Keywords: Biomass ; Carbon ; Chloroform fumigation ; Drying ; Mineralization flush ; Nitrogen ; Paddy soil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Soil samples of paddy fields with different fertilizer managements in Yamaguchi Agricultural Experiment Station, Japan were used to investigate the contribution of microbial biomass to the pool of mobile plant nutrients in paddy soil. The quantities of nutrients mobilized in soils which had been fumigated or dried were closely related to the quantities available in freshly killed biomass. A “KN-factor” (28 days) of 0.24 for the proportion of total N mineralized from dead biomass in paddy soils was obtained. It was observed that the C to N ratio mineralized from freshly killed biomass by chloroform fumigation of paddy soils was nearly 10 under aerobic conditions. For an approximate calculation of biomass C from the flush-N by chloroform fumigation of paddy soils, the equations of (B=33 Fn, 10 days) and (B=26 Fn, 28 days) were indicated. In oven-dried (70°C, 24 h) and rewetted soils, about 66% of N was mineralized from the freshly killed biomass during 28 days of incubation and the remaining 34% was derived from non-biomass organic matter of paddy soils.
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  • 49
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    Plant and soil 76 (1984), S. 233-241 
    ISSN: 1573-5036
    Keywords: Chemo-denitrification ; Iron oxyhydroxide ; Nitrate ; Nitric oxide ; Nitrite ; Nitrogen ; Nitrogen dioxide ; Reduced conditions ; Soil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Nitrite is very important in N transformation processes because it is an intermediate product in the aerobic nitrification as well as in the anaerobic denitrification process. Under soil conditions whereby aerobic and anaerobic zones are close to each other, the mobile nitrite can be a link between both N transformation processes. Because of its low stability in acid conditions, nitrite can be a key compound in N loss processes. The results are presented in three sets of incubation experiments using soil+added nitrite before and after oxidation of organic matter; soil+added nitrite and various iron oxide minerals; nitrite solutions without soil but with added ferrous iron. It was found that under acid conditions, soil organic matter as well as the soil mineral phase have a stimulating effect on the nitrite decomposition. Conditions favouring the solubility of Fe(III)-compounds and promoting the formation of Fe2+ increase the nitrite decomposition, even under slightly acid conditions. Of the gaseous decomposition products, only trace amounts of NO2 occur while NO is the major component. Conditions whereby NO and NO2 cannot escape from the medium promote production of some nitrite.
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  • 50
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    Plant and soil 76 (1984), S. 257-274 
    ISSN: 1573-5036
    Keywords: Biomass turnover ; Carbon ; Experimental verification ; Models ; Nitrogen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Many mathematical descriptions of C and N transformations in soils have been developed in the last decade, but only a few explicitly model the activity and mass of soil organisms. Great difficulties still exist in establishing basic parameters governing the kinetics of microbial turnover. The present state of the art is discussed briefly. The model of Van Veen and Frissel on C transformations and related mineralization and immobilization of N has been developed further based on laboratory and field data obtained with different Australian soils. Firstly, case studies show the large effects of the frequency of drying and rewetting of soils on the decomposition of organic matter and on the turnover of biomass. Secondly, the more refined model embraces the concept that soils have characteristic capacities to preserve both organic matter and microorganisms. Preservation of microorganisms could result from protection against predation and/or from amelioration of harsh environmental conditions. Biomass formed in excess of a soil's preservation capacity is assumed to die at a relatively high rate. Furthermore, biomass and its immediate organic products of decay are considered to form mainly a closed system from which only small proportions of the products leak out as stabilized materials. These concepts have been tested with data from laboratory experiments in which14C- and15N- labelled substrates and bacteria were added to a clay and sandy soil. Net mineralization of C and N (labelled and unlabelled) and changes in the total and labelled biomass as determined by the chloroform fumigation technique allowed for a thorough testing of these concepts in the manner in which they were included in the model. The fits between experimental observations and model outputs were very close. The model indicated that the contrasting metabolism of both C and N in a clayversus a sandy soil could largely be explained by differences in the capacities of the two soils to preserve microorganisms. The ability of a simulation model to describe accurately not only short-term events,e.g. N cycling during one growing season, but also the same processes over, say a decade, is an important criterion in assessing its predictive power. In this paper some of the results will be discussed of testing the model, developed from a consideration of the aforementioned laboratory studies, for its accuracy in describing the decomposition of plant residues in an 8-year field experiment.
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  • 51
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    Plant and soil 76 (1984), S. 77-91 
    ISSN: 1573-5036
    Keywords: Microorganisms ; Mycorrhizas ; Nitrogen fixation ; Phosphate uptake ; Rhizosphere
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary No root systems in nature are without a microbial population. These may be freeliving or symbiotic. The incidence and nutrition of the freeliving microorganisms is discussed. Shortage of substrate makes it unlikely that the N-fixers in the population can fix useful amounts of N. There is a possibility that P supply is improved, but an analysis of possible processes shows them to be rather unlikely, and evidence for them to be poor. Manganese and iron uptake can be altered by microbial activity. Growth of plants can be affected by non-nutritional bacterial effects. The ecology of Rhizobium in the soil is briefly discussed, and the varying needs of different identified strains is stressed. Mycorrhizal infection of plants leads to large growth increases in appropriate conditions. This is almost always linked to increased P uptake, but zinc and copper nutrition can also be improved. The processes involved are briefly discussed. Rapid and extensive infection is important; it is very sensitive to temperature. New modelling methods are now becoming available to measure the behaviour of the fungal infections. The microorganisms require C compounds from the plant, and new measurements of this cost are discussed. The possibility of practical use of mycorrhizal fungi seem to be improving.
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  • 52
    ISSN: 1573-5036
    Keywords: Hill soils ; Lime ; Mycorrhiza ; Nitrogen fixation ; Nodulation ; Phosphorus ; Rhizobium ; Symbioses ; White clover
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The responses of white clover (cv NZ Grasslands Huia grown in four UK hill soil types) to additions of lime and P, to inoculation with Rhizobium and mycorrhizal fungi, and to differences in soil water status were assessed in pot and field experiments. With a deep peat soil in pots, shoot production, nodulation and N fixation by clover were increased by 160, 130 and 85% respectively following inoculation with mycorrhiza, but in the field, despite a doubling of root infection, there was no response in growth. On a brown earth soil in the field inoculation with one endophyte (Glomus mosseae L1) out of four tested depressed production of white clover shoots by 42% but enhanced that of leeks (Allium porrum) by 50%; the others were without effect. With dry peaty podzol and brown earth soils in pots, clover shoot production was highest with added P when a water holding capacity of 80% was maintained, but roots from the latter had only 2.6 compared to 68 nodules per plant from the former. Further work is required to explain poor nodulation in the brown earth soils.
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  • 53
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    Plant and soil 76 (1984), S. 139-148 
    ISSN: 1573-5036
    Keywords: Chloroform-fumigation ; Microbial biomass ; Mor humus ; Nitrogen ; Peat ; Phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Samples of peat and mor humus were treated with CHCl3 to kill microbial cells and the amounts of C as CO2, N as soluble- and mineral-N, and P as inorganic-P released by the treatment were compared with estimates of the microbial biomass by the Anderson and Domsch test and ATP determination. Increased amounts of soluble-N and inorganic-P, extracted with 1M KCl and 0.01M CaCl2 respectively, were detected immediately after the fumigation treatment. However, the subsequent rates of production of CO2−C and mineral-N measured during a 10-day incubation period at 25°C were low and variable, resulting in anomalously low estimates of microbial biomass. The flush of inorganic-P was more consistent and, in mor humus, generally related to biomass-C as measured by the Anderson and Domsch test.
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  • 54
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    Plant and soil 76 (1984), S. 275-285 
    ISSN: 1573-5036
    Keywords: Biomass dynamics ; carbon ; Nitrogen ; Nutrient management ; Soil organic matter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Dynamics of C, N, S, and to some extent P are expressed by a knowledge of the size and turnover rates of plant constituents such as soluble C and N components, cellulose and hemicellulose, and lignin. Soil organic matter constituents include: the microbial biomass as determined chemically or microscopically, non-biomass active components determined by isotopic dilution, stabilized N constituents for which good techniques are not yet available, and resistant or old C and associated N determined by carbon dating. The processes involved in the nutrient transformations and transfers are reasonably well understood. The control mechanisms require further elucidation to be able to extrapolate from the laboratory to the field, and between field sites. Major control mechanisms requiring further insight include the effects of C availability on transformations of C and N. The other control for which every little is known is that of spatial compartmentalization. Compartmentalization ranges from landscape or management sequences to pedogenic layers, rhizosphere-mycorrhizal effects, clay-sesquioxide surfaces, aggregation, localized enzymes, and microbial effects such as membrane boundaries. Control mechanisms for concurrent mineralization-immobilization, the stabilization of microbial products, and the relative role of the biomass as a catalyst rather than as a source-sink for nutrients, must be understood. There is potential for combining a knowledge of microbial production and turnover with that of the roles of the soil organic active fraction as a temporary storehouse for nutrients. This, in conjunction with management techniques such as zero tillage and crop rotation, should make it possible to better utilize soil and fertilizer N, especially in areas of the world where the cost of nutrients is high relative to the value of the crop grown.
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  • 55
    ISSN: 1573-5036
    Keywords: Acetylene reduction ; Field method ; Medicago sativa L. ; Mucilaginous substances ; Nitrogen fixation ; Trigonella foenum-graecum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Summary A non-destructive method using a special device for measuringin situ acetylene reducting activity by nitrogen fixing plants is described. Plant roots are isolated from external atmosphere with a mucilaginous material laid on the soil around the plants. Acetylene or ethylene is directly injected into or taken from the soil around the nodules. Using this device the values of acetylene reducing activity ofTrigonella foenum graecum L. andMedicago sativa L. are much higher than those obtained with the same plants placed under polyethylene bags. This method is not expensive and allows the detection of low enzyme activities. It doesn't perturb plant physiology and can be used for young plants as well as for plants with ramified stems at their base.
    Notes: Résumé Les auteurs décrivent un dispositif qui permet de mesurer l'activité nitrogénasein situ par réduction de l'acétylène chez les plantes fixatrices d'azote, sans perturber leur physiologie et sans les détruire. Le système racinaire est isolé de l'atmosphère extérieure par une substance mucilagineuse déposée sur le sol autour des plantes testées. Les gaz acétylène ou éthylène sont injectés ou prélevés directement dans le sol au niveau des nodosités. Avec ce nouveau dispositif les valeurs de l'activité réductrice d'acétylène obtenues surTrigonella foenum-graecum L. etMedicago sativa L. cultivés en plein champ, sont très supérieures à celles mesurées sur ces mêmes végétaux enfermés dans une enceinte en polyéthylène. Cette méthode peu onéreuse, permet de détecter des activités réductrices faibles; elle est utilisable sur des jeunes plantes et également sur des individus ramifiés à la base.
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  • 56
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    Plant and soil 79 (1984), S. 37-49 
    ISSN: 1573-5036
    Keywords: Azotobacter ; Nitrogen fixation ; N2-fixing efficiency ; Respiration ; Soil ; Water potential
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Respiration and N2-fixation (acetylene reduction) ofAzotobacter vinelandii have been studied at a variety of soil water potentials. Both processes were strictly linked and strongly reduced at water potentials between −0.6 and −1.3 MPa. Complete inhibition occurred below −2.1MPa. Osmotic potentials in soil compared to matric potentials of the same value were less inhibitory to respiration and acetylene reduction by Azotobacter. The N2-fixing efficiency (mg N/g glucose) was not influenced by water potentials ranging from −0.1 to −2.1 MPa.
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  • 57
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    Plant and soil 79 (1984), S. 101-121 
    ISSN: 1573-5036
    Keywords: Base saturation ; Bio-climatic zones ; Calcium ; Clay accumulation ; Copper ; C:N ratio ; EDTA ; Forest soils ; Greece ; Iron ; Magnesium ; Manganese ; Nitrogen ; Phosphate ; Potassium ; Soil classification ; Zinc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Soils derived from a number of different parent materials (lithologies) and developed along a climatic gradient, manifested by the altitudinal succession of natural vegetation zones (Mediterranean, sub-Mediterranean, Mountainous and Pseudoalpine), were sampled throughout mainland Greece. In soils derived from siliceous parent materials low in clay, acidity increase and percent base saturation decreases from the Mediterranean to the Pseudoalpine vegetation zones. Clay illuviation is found mainly in soils developed in the Mediterranean and the sub-Mediterranean zones. No such changes are apparent in clayey soils rich in bases. Organic matter content of the mineral portion of the soil profile increases by a factor of 2 with a decrease in mean annual air temperature of about 10°C. The pattern of change in clay and soil organic matter content with climate is in relatively good agreement with soil development trends in the area, when soil profiles are named according to the FAO-Unesco soil map of the world. Concentrations of Ca and Mg decrease and those of total N, total and extractable P, K, Fe, Mn and Zn increase from the Mediterranean to the Mountainous zone. Within the same zone, however, concentrations of N, Ca, K, Fe, Mn and Zn decrease, but those of Mg, total and extractable P increase with soil depth. The concentrations of most macro- and micronutrients in the humic horizon are several times higher than those in the mineral portion of the soil profile due to biological enrichment.
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  • 58
    ISSN: 1573-5036
    Keywords: Acidity ; Aluminium ; Cowpea ; Nitrogen ; Rhizobium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The interaction of pH (4 or 6), aluminium (0 or 16 ppm at pH 4) and N source (symbiotic or combined) on the growth and nutrient status of cowpea (Vigna unguiculata) was studied in a glasshouse experiment. Low pH significantly decreased the growth of the plants dependent on symbiotic nitrogen fixation but at pH 4 the addition of 16 ppm Al further depressed growth in both nitrogen regimes. Al-ions appear to exert their effect primarily on the root system, as shown by the reduction in total length and fresh weight. The symbiotic development of the plants was affected by low pH but more markedly by the Al treatment. Shoot nitrogen concentrations were reduced from ca. 2.6% at pH 6 to 1.8% and 0.9% at pH 4 without and with aluminium respectively. Calcium concentration was decreased by low pH and further by Al in both nitrogen regimes. In all Al-treated plants, the aluminium was mainly accumulated in the roots and was associated with an increase in their phosphorus concentration.
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  • 59
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    Plant and soil 81 (1984), S. 291-293 
    ISSN: 1573-5036
    Keywords: Casuarinaceae ; Citrulline ; Frankia ; Nitrogen ; Nutrition ; Xylem sap
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The major nitrogenous compound in the xylem sap ofCasuarina equisetifolia is citrulline, irrespective of nitrogen nutrition (dinitrogen fixation, nitrate or ammonium). The detection of citrulline in non-nodulated Casuarina suggests that its formation is not confined to root nodules. This precludes the possibility of using the relative citrulline content of xylem sap for quantification of N2 fixation in Casuarina. The possibility exists, however, that the relative abundance of citrulline to other nitrogenous compounds (e.g. amides or nitrate) in the xylem sap could be used as an indicator of N2 fixation and should be evaluated further.
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  • 60
    ISSN: 1573-5036
    Keywords: C2H2 reduction ; Intact-plant assay ; Millet ; Nitrogen fixation ; Nitrogenase activity ; Sorghum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A non destructive intact-plant assay for estimating nitrogenase activity (C2H2 reduction) of pot-grown sorghum and millet plants is described. Plants with intact shoots sustained more activity than plants whose tops were removed prior to the assay. With this technique individual plants can be assayed several times during their life cycle. The C2H2 reduction was linear up to 16h incubation in this assay procedure. More rapid diffusion of C2H2 was achieved by injection through a Suba seal in the bottom of the pot. The equlibration of injected C2H2 in the gas phase of the pots filled with sand and sand:FYM media was completed within 1 h. Significantly higher nitrogenase activity and better growth of sorghum and millet plants occurred when plants were grown in a mixture of sand and farmyard manure (FYM) than when plants were grown in vermiculite, soil, or sand + soil medium. Nitrogenase activity and plant growth were greater in a mixture of sand with 2 and 3% FYM than with 0.5 and 1% FYM. Activity was higher when the plants were incubated at 33°C and 40°C than at 27°C. Activity also increased with increasing soil moisture. There were significant differences amongst 15 sorghum cultivars screened for associated nitrogenase activity. This new technique has good prospects for screening cultivars of millet, sorghum and other grain crops for their nitrogen-fixing ability.
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  • 61
    ISSN: 1573-5036
    Keywords: Azospirillum brasilense ; Azotobacter chroococcum ; Effect on yield ; Inoculation ; Nitrogen fixation ; Setaria italica
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Under controlled conditions in pots filled with sand, vermiculite and field soil, inoculation withA. brasilense-Cd ATCC 29729 or withAzotobacter chroococcum caused increases above controls in the weight and N content of panicles ofSetaria italica. In no case, however, did N increases in test plants exceed the initial total N content. High acetylene reduction activities (1,000–2,000 nmole/h/pot) could be found only in plants inoculated withAzospirillum. Inoculation withAzospirillum (strain-Cd) in the field caused a significant increase above noninoculated controls of 18.5% in shoot dry weight, ofSetaria italica. Azotobacter caused a non significant increase of 8%. No significant differences were found between yields ofSetaria italica grown in soil inoculated withA. chroococcum, and those of plants grown in the presence ofA. vinelandii. A. brasilense-Cd was more effective in the field thanA. brasilense Sp-7 ATCC 29145. The results suggest that Azospirillum may increase yields ofS. italica more efficiently than Azotobacter under local field conditions.
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  • 62
    ISSN: 1573-5036
    Keywords: Clover ; Nitrogen fixation ; Rhizobium ; Root nodule ; Selection and plant breeding ; Symbiosis ; Trifolium pratense ; T. subterraneum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary This paper reviews (i) basic studies on the genetics of symbiosis in red clover (a self-sterile species) and subterranean clover (cleistogamous) and (ii) work on selection and plant breeding to increase nitrogen fixation in these hosts. Symbiotic effectiveness in red clover is influenced by many major and minor genes. The highly effective phenotype is inherited in a complex manner associated with early nodulation and the formation of large amounts of persistent bacteroid-containing tissue. Lines bred to fix more nitrogen with one strain ofRhizobium trifolii do so with most but not all other strains examined. They also show slightly increased vigour when grown on nitrate. The highly effective response is correlated with abundant nodulation and an early flowering habit, the evidence from breeding studies indicating that this correlation is not absolute. Normally effective and highly effective nodules have the same specific nitrogenase activities. The expression of the highly effective response is relatively little affected by environmental factors (temperature, light intensity, day length, supplementary carbon-di-oxide). Inbreeding substantially degrades the symbiotic response. Heterosis is shown in crosses between cultivars of subterranean clover but otherwise selection to increase effectiveness in this host was unsuccessful. The relevance of these results (and their physiological aspects) for the improvement of grain legumes is discussed.
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  • 63
    ISSN: 1573-5036
    Keywords: Balsam fir ; Foliar analysis ; Lime ; Nitrogen ; Phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The following fertilizer treatments were applied to a 20-year-old aspen-birch-sprucefir stand in southeastern Maine: N at 448 kg/ha, P at 112 kg/ha, N and P applied as above in addition to 1751 kg/ha Ca and 27 kg/ha Mg. Five years after treatment, foliar concentrations of N, P and Ca for understory blasam fir exhibited significant increases in response to fertilization with those nutrients. Mean five-year height growth, adjusted for pretreatment differences, increased 36 percent in response to fertilization with N alone and in combination with P and lime.
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  • 64
    ISSN: 1573-5036
    Keywords: Calcium ; Eucalyptus saligna ; Eucalyptus wandoo ; Foliar nutrients ; Magnesium ; Nitrogen ; Phosphorus ; Potassium ; Rehabilitation ; Seasonal trends
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Seasonal changes in the foliar concentration of macronutrients (N, P, K, Ca and Mg) in sapling trees ofEucalyptus saligna Sm. andE. wandoo Blakely growing in rehabilitated bauxite mined areas in the Darling Range of Western Australia are described. Foliar N concentration decreased with age of the fully expanded leaf tissue. Leaf N concentrations were also high when rates of litter decomposition were expected to be high during the period of early spring. The greatest foliar N difference between trees growing in good soil conditions and those from poorer soil conditions also occurred during this period. Levels of P in leaves were highest in young developing leaves but once the leaves reached full size, no seasonal trend in P concentration was observed. Foliar K was lower during the winter and probably related to the period of maximum leaching by precipitation. High foliar K during summer, however, could be related to the role of K in lowering cellular water potential. Leaf Ca was highest during early sping. Low mobility of cellular Ca during the cool portion of the year was indicated. Foliar Mg showed a weak pattern of decreasing concentration with leaf age. The best season for sampling for these broadleafed evergreen species to provide information on plant nutrient status appears to be in spring.
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  • 65
    ISSN: 1573-5036
    Keywords: Assimilates distribution ; 14CO2 and15N2 labelling ; Glycine max L. Merrill ; Nitrogen fixation ; Respiration costs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Summary Distribution and use of photoassimilated carbon by nodulated soybeans (Glycine max L. Merr.) grown in natural conditions have been studied during two consecutive years by successive and simultaneous exposures of the plants to14CO2 and15N2 during one day. This method, together with detailed analysis of CO2 efflux by root systems made it possible to follow the fate of carbon in relation to dinitrogen fixation. The results showed that the stage of development at which the plants were labelled exerted a high influence on the initial distribution of carbon. The growing organs always attracted more of the recently assimilated carbon. So, the reproductive parts accumulated increasing proportions and by day 100 about 70% of the current net production was recovered in pods and seeds. Nodules stored from 3 to 5% of the daily production, from day 50 to day 100, when their fixation activity already dropped by day 85. During the period of optimal fixation the amount of carbon lost as CO2 due to the only process of N2 reduction ranged between 2.5 and 7 mg per mg of N2 fixed. This was equivalent to the amount of carbon directed towards roots and nodules structures during the same time. Secondary transfers by remobilization occurred from leaves and pods to the grains but mainly from the carbon assimilated during the podfilling stage (after day 80). However, these amounts were small indicating that grain development is mainly supported by current assimilates.
    Notes: Resumé La distribution et l'utilisation du carbone photoassimilé par des sojas (Glycine max L. Merr.) nodulés, cultivés en conditions naturelles ont été suivies durant deux années consécutives par expositions répétées et simultanées de plantes à du14CO2 et15N2 pendant une journée. Cette méthode couplée à une analyse détaillée des flux respiratoires au niveau des systèmes racinaires a permis de suivre le devenir du carbone en relation avec l'activité fixatrice d'azote. Les résultats montrent que le stade de développement des plantes au moment du marquage exerce une forte influence sur la distribution initiale du carbone. Ce sont les organes en forte croissance qui attirent le plus d'assimilats récents. Ainsi les organes reproducteurs, accumulent des quantités croissantes à partir de leur formation si bien qu'aux environs du jour 100, ils attirent près de 70% de la production nette. Les nodules eux stockent da 3 à 5% de cette production journalière entre les jours 50 et 100 alors que leur activité fixatrice chute déjà fortement dès le jour 85. Pendant la phase d'activité fixatrice optimale, les quantités de carbone perdues sous forme de CO2, pour le seul processus de réduction du N2, varient entre 2,5 et 7 mg par mg d'azote fixé. Ceci équivaut à la quantité de carbone destinée aux structures “racines et nodules”. Les transferts secondaires d'organes à organes se font à partir des organes végétatifs et puis des gousses vers les graines, mais essentiellement à partir de carbone assimilé durant la phase de remplissage des gousses (après le jour 80). Cependant, les quantités remobilisées sont faibles, ce qui indique que la croissance des graines dépend surtout d'une alimentation directe à partir de la photosynthèse.
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  • 66
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    Plant and soil 82 (1984), S. 273-284 
    ISSN: 1573-5036
    Keywords: Legume ; Nitrogen fixation ; Rhizobium ; C and N economy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Studies of the C and N economy of a range of temperate and tropical legume/Rhizobium symbioses indicate considerable variation (up to three-fold) in the cost of N2 fixation. Comparisons between and within symbioses indicate that the proportion of net photosynthate utilized in nodule functioning varies almost ten-fold from as low as 3% to as high as 25%. Factors possibly responsible for variation in efficiency of C use in nodules and in the proportioning of translocated photosynthetic products to nodules are discussed.
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  • 67
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    Plant and soil 80 (1984), S. 391-405 
    ISSN: 1573-5036
    Keywords: Carbon ; Clear cutting ; Exponential decay ; Forest ; Litter ; Mineralization ; Nitrogen ; Podzol ; Respiration ; Rhizosphere Soil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Leaf litter breakdown and fine root production, including exudation, are two major influences upon carbon and nitrogen mineralization rates in forest soil. Sieving and root removal experiments were used to examine their effects. Although carbon mineralization rates declined in smaller particle size fractions of forest litter, this trend largely disappeared when results were calculated on an ash-free basis. Nitrogen mineralization by contrast, was greatest in smaller fractions. Much of the variation in carbon mineralization rates appeared to be associated with fine roots. A rapid initial exponential decay phase noted in laboratory respiration studies was probably associated with disappearance of available carbon in the form of root exudates and/or the microorganisms dependent on them. Clear cutting caused a marked reduction in the size of available carbon pools, reflecting decreased root exudation and rhizosphere activity. A model of mineralization is proposed which represents the available and humified carbon pools.
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  • 68
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    Plant and soil 81 (1984), S. 133-141 
    ISSN: 1573-5036
    Keywords: Benomyl ; Pesticides ; Nitrogen fixation ; Soybeans
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Benomyl applied to the seeds of soybean (Glycine max L. Merrill) inoculated with a benomyl resistant strain ofRhizobium japonicum increased the relative abundance of nodules formed by the inoculum strain and the numbers of the added rhizobium on the roots, the total N content, the percentage N, the yield at one plant density and, in one of four soils, the pod weight of soybeans grown in the greenhouse. Oxamyl applied to the seeds, foliage or both of soybeans inoculated with an oxamyl resistant strain ofR. japonicum increased the yield, N content, percentage N, and weight of nodules, pods and grain and enhanced the relative frequency of nodules formed by the inoculum strain. It is suggested that pesticides or other antimicrobial agents and rhizobia resistant to these inhibitors may provide a new means for increasing nitrogen fixation by soybeans.
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  • 69
    ISSN: 1573-5036
    Keywords: Azospirillum lipoferum ; Grain yield ; N-content ; Nitrogen fixation ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Spring wheat (Triticum aestivum var. Arkas) was associated withAzospirillum lipoferum under greenhouse and field conditions of a temperate region. Controls were treated with autoclaved bacteria. The soils used were: sand, sandy loam, and a peat-clay mixture. In experiments run over a period of three years, there were increases in grain yield, N-yield of the grains, and 1000 grain weight. Depending from environmental conditions, increase changed from year to year, and within one given year. There was, however, no experiment without positive response to the inoculation. Highest grain yield increase (70%) was found on sand supplemented with P and K only, but up to 32% were also obtained on peat-clay soil containing 0.28% total N. Under greenhouse conditions, one third of technical N-fertilizer could be saved by bacterial activities. With high probability the effects observed have been at least partly due to bacterial N2-fixation, because the N-yield of the grains was increased (up to 33%), and the most pronounced response was found on sand without any N-fertilizer added.
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  • 70
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    Plant and soil 82 (1984), S. 329-335 
    ISSN: 1573-5036
    Keywords: Legume breeding ; Medicago sativa ; Nitrogen fixation ; Rhizobium ; Trifolium repens ; Vicia faba
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary This paper examines evidence which quantifies the relative importance of legume and Rhizobium genotypes as determinants of phenotypic variation in symbiotic nitrogen fixation. It demonstrates potentially large and unpredictable effects of the Rhizobium genotype. The likely importance of such effects on crop yield is considered. The information is then used to assess ways in which legume breeding programmes may be altered to encompass the effects of genetic variation in Rhizobium.
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  • 71
    ISSN: 1573-5036
    Keywords: Co-evolution ; Domestication ; Gene centre ; Genetic variability ; Nitrogen fixation ; Pisum sativum L ; Rhizobium leguminosarum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Soil samples from several European countries; Sweden, the Netherlands, Spain, Italy and Greece, contained rhizobial populations capable of forming an effective symbiosis with the cultivated pea cv. Rondo from the Netherlands. The range of variation among the European Rhizobium strains, as expressed on pea cv. Rondo, was not so large and almost the same variation could be found within the rhizobial population within each country. Superior Rhizobium strains for the Dutch pea were not restricted to soils from the Netherlands but were also found in those from Sweden and Italy. Soils from Turkey and Israel also contained Rhizobium strains capable of nodulating pea cv. Rondo. However, the genetic variation among these Middle East Rhizobium strains was much larger than that of the European strains. When tested on pea cv. Rondo the majority of the Middle East strains belonged to the medium or low effective classes and only a few strains were comparable with European Rhizobium strains. Dutch Rhizobium strains induced effective nodules on both the Dutch pea cv. Rondo and the Swedish cv. L 110. However, in association with a Turkish Rhizobium strain effective nodules were formed on pea cv. Rondo and ineffective nodules on cv. L 110. We suggest that the genetic uniformity of EuropeanR. leguminosarum strains is the result of selection and domestication of Rhizobium strains originally derived from the gene centres of the pea plant.
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  • 72
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    Nutrient cycling in agroecosystems 5 (1984), S. 245-257 
    ISSN: 1573-0867
    Keywords: Adamantane-type compounds ; Fertilizer ; High analysis nutrient compounds ; Nitrogen ; Phosphorus ; Phytotoxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In a preliminary assessment of the fertilizer capability of three high analysis NP(S) compounds, their possible phytotoxic effects were investigated in solution culture tubes. One of the compounds was studied in more detail in pot experiments with sand and a red-brown earth soil. Two adamantane-type compounds (APA and APAS) were capable of supplying N and P to plants, but also showed toxicity effects. With APA, this effect appeared to be dissipated in soil but not in sand. The toxic effect was alleviated by addition of soluble P or soluble P + N. Some plants absorbed excessive amounts of P, probably not all in the form of orthophosphate.
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  • 73
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    Plant and soil 81 (1984), S. 421-428 
    ISSN: 1573-5036
    Keywords: Acetylene inhibition ; Denitrifiers ; Electron acceptor ; Incubation ; Nitrate ; Nitrous oxide ; Nitrogen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A total of 81 strains isolated by T. N. Gamble from soils from eight countries, fresh water lake sediments and nitrified poultry manure were examined for their ability to grow on N2O as their electron acceptor, as well as for their tendency to produce N2O from NO 3 − in the absence and presence of acetylene. Seventy-seven of the 81 strains were confirmed as denitrifiers. Fifty-nine of the 77 strains grew on N2O, while 12 strains produced N2O but could not utilize it. Six strains reduced NO 3 − to N2 but could not grow on N2O, suggesting that even if N2O is always an intermediate product of denitrification, it is not always a freely diffusible intermediate. The organisms, however, would consume N2O that accumulated early in growth and accumulated N2O in the presence of acetylene. Thus the total number of N2O users was 65 strains or 83% of the total tested. This implies that the N2O reducing capacity of denitrifiers occur widely in nature. A high proportion ofPseudomonas fluorescens biotype II reduced N2O. The accumulation of N2O from NO 3 − in the presence of acetylene provides strong evidence that N2O is generally an intermediate in denitrification as well as provides additional support for the usefulness of this chemical as a general inhibitor of N2O reduction.
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  • 74
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    Plant and soil 82 (1984), S. 315-327 
    ISSN: 1573-5036
    Keywords: Breeding ; Competition ; Glycine max ; Nitrogen fixation ; Nodulation ; Phaseolus vulgaris
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary While symbiotic nitrogen (N2) fixation byG. max andP. vulgaris reduces their need for combined N, N2 fixation under field conditions is rarely maximized. This paper reviews constraints to N2 fixation in these species, then examines the genetic variability recorded for traits affecting N2 fixation and the further work needed in this area. It considers emerging programs for the improvement of N2 fixation inG. max andP. vulgaris and pays particular attention to methodological considerations.
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  • 75
    ISSN: 1573-5036
    Keywords: Citrus ; Controlled-release fertilizers ; Nitrogen ; Nutrition ; Sulfur-coated urea ; Ammonium nitrosulphate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The effect of one application of the slow-release fertilizer, sulfur-coated urea, on the nitrogen level in leaves, fruit and bark of Washington Navel orange trees was studied during the different periods of the annual vegetative cycle, in comparison with two annual applications of the fertilizer ammonium nitrosulphate. Results indicate that a single spring application of 750 g nitrogen per tree maintains N levels in old leaves, spring shoots, ovaries, fruit and bark statistically equal to those obtained using double doses of ANS in two applications.
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  • 76
    ISSN: 1573-5036
    Keywords: Branch nutrients ; Calcium ; Eucalyptus saligna ; Eucalyptus wandoo ; Foliar nutrients ; Magnesium ; Nitrogen ; Phosphorus ; Potassium ; Rehabilitation ; Soil nutrients
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The macronutrient variation within four 6 year oldEucalyptus saligna and four 5 year oldE. wandoo growing on rehabilitated bauxite pits was determined. Significant differences in mean nutrient concentrations were generally recorded between good soil condition sites and poor soil sites, between tree individuals, branch height, and plant organ type; but mean nutrient values were not different among canopy aspects. Fully expanded leaves of the current year provided the most uniform nutrient levels among the plant organs and showed major differences between sites with good soil nutrient conditions and those with poor conditions. Differences in foliar and branch levels of N, P, K, Ca and Mg, the variation between sites, canopy heights and plant organ types, and the use of foliar nutrient levels to indicate deficiencies are discussed.
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