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  • Articles  (159)
  • maize  (55)
  • biological control  (38)
  • Oryza sativa  (34)
  • Solanum tuberosum L.  (33)
  • 2015-2019
  • 1995-1999
  • 1990-1994  (159)
  • 1940-1944
  • 1915-1919
  • 1993  (78)
  • 1990  (81)
  • Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition  (159)
  • Geosciences  (3)
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  • Sociology
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  • Articles  (159)
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  • 2015-2019
  • 1995-1999
  • 1990-1994  (159)
  • 1940-1944
  • 1915-1919
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  • 1
    Electronic Resource
    Electronic Resource
    Effects of nitrification inhibitors and time and rate of slurry and fertilizer N application on silage maize yield and losses to the environment (1993)
    Springer
    Nutrient cycling in agroecosystems 34 (1993), S. 267-277 
    Details
    ISSN: 1573-0867
    Keywords: animal manure ; leaching ; maize ; nitrification inhibitor ; nitrogen recovery
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Field experiments with silage maize during eight years on a sandy soil in The Netherlands, showed that dicyandiamide (DCD) addition to autumn-applied cattle slurry retarded nitrification, thus reducing nitrate losses during winter. Spring-applied slurry without DCD, however, was on average associated with even lower losses and higher maize dry matter yields. Economically optimum supplies of mineral N in the upper 0.6 m soil layer in spring (EOSMN), amounted to 130–220 kg ha−1. Year to year variation of EOSMN could not be attributed to crop demand only. According to balance sheet calculations on control plots, apparent N mineralization between years varied from 0.36 to 0.94 kg ha−1 d−1. On average, forty percent of the soil mineral N (SMN) supply in spring, was lost during the growing season. Hence, the amounts of residual soil mineral N (RSMN) were lower than expected. Multiple regression with SMN in spring, N crop uptake and cumulative rainfall as explanatory variables, could account for 79 percent of the variation in RSMN. Postponement of slurry applications to spring and limiting N inputs to economically optimum rates, were insufficient measures to keep the nitrate concentration in groundwater below the EC level for drinking water.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00750573
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  • 2
    Electronic Resource
    Electronic Resource
    Effect on maize growth of the interaction between increased nitrogen availability and competition with trees in alley cropping (1993)
    Springer
    Agroforestry systems 21 (1993), S. 239-249 
    Details
    ISSN: 1572-9680
    Keywords: Erythrina ; Gliricidia ; alley cropping ; maize ; competition ; nitrogen availability ; Costa Rica
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Maize growing next toErythrina hedgerows had 44% lower biomass (p〈0.01) and 35% lower N content (p〈0.1) than maize growing in the middle of the alleys. Maize growing next toGliricidia hedgerows had the same biomass but 56% higher N content (p〈0.1) than maize growing in the middle of the alleys. However these differences did not develop until 2 months after sowing of the maize. Spatial variability in soil nitrogen mineralization and mulch nitrogen release did not explain any of the differences in growth or N uptake of the maize with respect to distance from the trees. It is hypothesized that the slower growth of the maize next to theErythrina trees after 2 months is due to increasing light and/or nutrient competition from the trees as the trees recover from pollarding. The apparent lack of competition fromGlirigidia may be due to different rates of regrowth or different shoot and root architecture. A theoretical model is described demonstrating that if a crop is to take advantage of the higher nutrient availability under alley cropping it must complete the major part of its growth before the trees recover significantly from pollarding, and start competing strongly with the crop.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00705243
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  • 3
    Electronic Resource
    Electronic Resource
    The potential of alley cropping in improvement of cultivation systems in the high rainfall areas of Zambia. III. Effects on soil chemical and physical properties (1993)
    Springer
    Agroforestry systems 21 (1993), S. 117-132 
    Details
    ISSN: 1572-9680
    Keywords: alley cropping ; maize ; nitrogen ; organic matter ; soil fertility ; Leucaena leucocephala ; Flemingia congesta
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A detailed study of the soil chemical and physical properties in seven-year-old alley cropping trial containingLeucaena leucocephala andFlemingia congesta in Northern Zambia is described. There was a strong correlation between the maize yield and the total amount of nitrogen applied, both from prunings and fertiliser, suggesting that a major reason for the observed benefit from alley cropping, particularly withLeucaena, was due to an improvement in nitrogen supply.Leucaena produced significantly more biomass, and its leaves had higher concentrations of nitrogen, phosphorous and potassium and lower C/N and C/P ratios than did those ofFlemingia. There was also evidence that the trees had a beneficial effect on other soil chemical properties; under the hedgerows, particularly those ofLeucaena, there were higher levels of organic carbon, Mg, K and ECEC, and pH values were also highest. It is suggested that higher levels of organic carbon in the alley crop treatments were responsible for the improvements observed in soil physical properties. Lower bulk density, lower penetration resistance, and a higher infiltration rate and pore volume fraction were measured in the alley crops, although there was no significant change in the soil water release parameters. A deteriorating effect of constant applications of nitrogen fertiliser on soil fertility was observed; as the level of urea application increased, there were significant decreases in Mg, K and pH, increases in Al and soil acidity, and higher penetrometer resistance. These results highlight the urgent need for further research on biological methods of maintaining soil fertility.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00705224
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  • 4
    Electronic Resource
    Electronic Resource
    Effects of inoculation with N2-fixing cyanobacteria on the nitrogenase activity in soil and rhizosphere of wetland rice (Oryza sativa L.) (1993)
    Springer
    Biology and fertility of soils 16 (1993), S. 16-20 
    Details
    ISSN: 1432-0789
    Keywords: Nitrogenase activity ; Acetylene reduction activity ; ARA ; Cyanobacteria ; Soil inoculation ; Wetland rice ; Root system ; Oryza sativa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A greenhouse experiment was conducted with wetland rice (Oryza sativa cv. IR-50) in a clay-loam soil (Fluventic Eutrochrept) to study the effect of cyanobacterial inoculation a mixed culture of Aulosira fertilissima, Nostoc muscorum, Nostoc spp., and Anabaena spp., applied at the rate of 0.15 g (dry weight pot-1 or 43 kg ha-1) on acetylene reduction activity in soil and the root system (excised root), and the grain and straw yield. The effects of applying P (40 kg ha-1), N (60 kg ha-1), and P+N to the soil were also evaluated. Cyanbacterial inoculation significantly increased (more than 200% on average) photo-dependent acetylene reduction activity in soils, particularly where the indigenous activity was considerably low, i.e. under unfertilized and N-fertilized conditions. The effect of inoculation was prominent at the maximum tillering and grain formation stages of the crop. This inoculation benefit was, however, marginal in P-applied soils (P and P+N), where the indigenous activity was stimulated more than threefold. The inoculation led to a remarkable increase in root-associative acetylene reduction activity after the maximum tillering stage of the crop, particularly with applied N but for other treatments this inoculation effect was not significant. Cyanobacterial inoculation also increased the grain and straw yield of the crop when N was not applied. The grain and straw yield was significantly correlated with the acetylene reduction activity in flooded soils and in the root system during the tillering and maximum tillering stages of rice growth, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00336509
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  • 5
    Electronic Resource
    Electronic Resource
    Yield stability and fertilizer efficiency of long-term triple cereal cropping in paddy fields of China (1993)
    Springer
    Biology and fertility of soils 16 (1993), S. 151-153 
    Details
    ISSN: 1432-0789
    Keywords: Triple cereal cropping ; Barley ; double-cropped rice ; Oryza sativa ; Wetland rice soils ; Stable grain yield ; Organic manuring ; Sustainability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Triple cereal cropping is an important grain production pattern which has been adopted on a vast area of paddy fields in Southern China. A long-term triple cereal cropping (barely with double-cropped rice) experiment has been conducted for 18 years (1974–1991) in paddy fields on the southern coastal plain of Zhejiang. The results showed that long-term triple cereal cropping has a high and stable grain yield level if certain improved crop varieties are used. Furthermore, the use of organic manure to reduce yield fluctuations and promote N-use efficiency was evaluated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00369418
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  • 6
    Electronic Resource
    Electronic Resource
    A glasshouse test for assessing resistance to early blight (Alternaria solani) (1993)
    Springer
    Potato research 36 (1993), S. 35-42 
    Details
    ISSN: 1871-4528
    Keywords: Solanum tuberosum L. ; disease screening ; maturity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Fourteen genotypes of potato were assessed for resistance toAlternaria solani Sor., both in the glasshouse at the Scottish Crop Research Institute in Scotland and in the field in the Negev, Israel. Glasshouse assessments agreed well with field results, identifying the most resistant and susceptible genotypes. The effects on the glasshouse test of plant age, inoculum concentration, and length of time plants were kept damp after inoculation, were examined. The best agreement with field results was shown by plants inoculated at flowering, and the best discrimination between genotypes was achieved by keeping the foliage damp for 24 h after inoculating with a spore suspension containing 2.5×103 spores/ml.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02359832
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  • 7
    Electronic Resource
    Electronic Resource
    Performance of potato minitubers in a controlled environment after different storage periods (1993)
    Springer
    Potato research 36 (1993), S. 283-292 
    Details
    ISSN: 1871-4528
    Keywords: Solanum tuberosum L. ; rapid multiplication ; seed production ; non-destructive harvest ; physiological age ; cultivar ; stem number
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Minitubers of cultivars Agria and Liseta were harvested from the same plantlets on three dates. After each harvest, tubers were dried (1 day), cured (13 days) and cold stored at 2 °C in darkness and 80 % RH. Their performance was studied 65, 128, 191, 254, 317, 380, 443, 506 and 569 days after harvest. Minitubers (1–2 g) were planted in pots and grown for 8 weeks in a controlled environment. After 191 days of storage their growth was still extremely poor. In both cultivars, tallest plants and largest leaf areas per plant were observed in plants from tubers from the second and third harvests that had been stored for 317 days. Highest stem numbers, yields (total dry matter, tuber fresh weight) and harvest indices were achieved with 443 days storage with cv. Agria and 569 days storage with cv. Liseta. Tubers from the first harvest behaved slightly differently.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02361794
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  • 8
    Electronic Resource
    Electronic Resource
    Etablierung von Kartoffelsorten im Feld nach physiologischer Alterung der Pflanzknollen (1993)
    Springer
    Potato research 36 (1993), S. 143-151 
    Details
    ISSN: 1871-4528
    Keywords: Solanum tuberosum L. ; Warmlagerung ; Keimintensität ; Schwund ; Aufgangsverspätung ; Bestandesdichte ; Ertrag
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Summary Seed tubers were stored at above optimal temperatures. Mean temperatures varied during test years from 16 to 29.5°C (in 1988–1990 tubers desprouted before planting; in 1991 chitted tubers as in control; Table 1). This procedure of physiological ageing of seed tubers resulted in reduced plant density and lower yield compared to the chitted control in every year of the test period (average of 25 cultivars). The emergence was significantly delayed as compared to the control in all years (Table 2). Assessed for yield, the cultivars Désirée, Sanetta, Astilla and Andra showed a significantly higher degree of tolerance to warm storages (〉80%, when compared to the control) than the cultivars Arkula, Dorisa, Karlena and Koretta (〈25%; Table 3). Between these two extremes there was a large number of intermediate levels of tolerance, a result of fluctuating reactions of various cultivars to changing conditions in the years of the test period (Fig. 1). No correlation could be found between the cultivars' reactions and their maturity group or their sprouting behaviour. There was, however, for each cultivar a significant negative correlation between loss in weight through transpiration and respiration and plant density and yield (r=−0.55 and −0.54; Table 4). Plant density and yield were closely correlated (Table 4). The regressions between loss of plants and reductions in yields show that after seed tuber storage at higher temperatures a reduced yield must be expected even when plant density is not reduced (loss of plant 0%; Fig. 2). With complete stands, the use of physiologically aged seed tubers that were desprouted before planting (1988–1990) resulted in a reduction of yield of 17–20%; when old seeds were chitted as in control a loss in yield of 15% was calculated.
    Notes: Zusammenfassung Die physiologische Alterung der Pflanzknollen durch Lagerung bei überoptimalen Temperaturen (jahresunterschiedlich 16–29,5°C, 1988–90 vor dem Pflanzen abgekeimt, 1991 vorgekeimt wie Kontrolle) führte im Vergleich zur vorgekeimten Kontrolle im Mittel von 25 Sorten in allen Versuchsjahren zu einer Verminderung der Bestandesdichte und des Ertrages. Eine Gruppe von Sorten erwies sich in allen Jahren als relativ tolerant gegen die Alterung, eine andere als signifikant empfindlicher, dazwischen lag ein breites Mittelfeld mit zum Teil erheblichen Schwankungen in den Jahren. Die Reaktion der Sorten zeigte keine Beziehung zu ihrer Reifegruppe und ihrer Keimintensität, dagegen war die sortentypische Ertragsdepression nicht sehr eng, aber signifikant mit dem Schwund während der Lagerung korreliert.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02358729
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  • 9
    Electronic Resource
    Electronic Resource
    The effect of the moisture level of potting compost on the susceptibility of glasshouse-grown tubers to late blight (1993)
    Springer
    Potato research 36 (1993), S. 29-33 
    Details
    ISSN: 1871-4528
    Keywords: Solanum tuberosum L. ; Phytophthora infestans
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The effect of the moisture level of potting compost at harvest on the susceptibility of tubers of three cultivars to late blight was investigated in the glasshouse in three successive years. Three moisture regimes (dry, moist, wet) were imposed at flowering time, the tubers harvested 3 weeks later and immediately dipped in a zoospore suspension ofPhytophthora infestans. Tubers from dry compost were significantly more susceptible than those from wet or moist compost, which showed similar levels of susceptibility.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02359831
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  • 10
    Electronic Resource
    Electronic Resource
    Resistance to late blight (Phytophthora infestans (Mont.) de Bary) of potato plants regenerated fromin vitro selected calli (1993)
    Springer
    Potato research 36 (1993), S. 341-351 
    Details
    ISSN: 1871-4528
    Keywords: culture filtrate ; resistant variants ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Cells of seven potato cultivars were selectedin vitro with culture filtrate (CF) ofPhytophthora infestans (Mont.) de Bary. Regenerated plants were tested for late blight resistance. The aim of the study was to check the efficacy of CF in the selection of potatoes for resistance to late blight and to evaluate the effects of additive factors on general resistance. One selection cycle, applied to a cell culture system, selected cells resistant to toxic metabolites of CF.In vivo screening of clones regenerated from selected cells was done in two steps: on whole plants, assessing foliage late blight, and on detached leaves, assessing single factors of horizontal resistance. In general, the frequency of resistant variants selected with CF did not differ from that of resistant somaclonal variants. Nevertheless, high concentrations of CF in the growth medium seemed to induce an improvement of some partial resistance factors as compared with the source plants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02361801
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  • 11
    Electronic Resource
    Electronic Resource
    Assessing general combining ability for late blight resistance and tuber characteristics by means of glasshouse seedling tests (1993)
    Springer
    Potato research 36 (1993), S. 353-357 
    Details
    ISSN: 1871-4528
    Keywords: foliage blight ; tuber blight ; Phytophthora infestans ; breeders' preference score ; specific combining ability ; potato ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Screening tests to detect resistance to late blight in both foliage and tubers were done on glasshouse-grown seedling progenies in parallel with visual assessments by three experienced potato breeders of the yield and quality of glasshouse-grown tubers of the same progenies. There were large differences between the parents of the progenies in their general combining ability (GCA) for both foliage and tuber blight, despite some variation due to specific combining ability for foliage blight. There were also differences between parents in their GCAs for visual preference scores, but these GCAs and those for blight resistance were not correlated. The blight-resistant cv. Stirling had the best combination of high GCAs for all three attributes. The use of these and other seedling progeny tests in a multitrait genotypic recurrent selection scheme is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02361802
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  • 12
    Electronic Resource
    Electronic Resource
    Post-harvest characteristics of potato minitubers with different fresh weights and from different harvests. II. Losses during storage (1993)
    Springer
    Potato research 36 (1993), S. 273-282 
    Details
    ISSN: 1871-4528
    Keywords: Solanum tuberosum L. ; seed size ; rapid multiplication ; seed production ; non-destructive harvest ; water loss
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Storage losses were studied in minitubers of cvs Agria and Liseta, using five fresh weight classes (〈0.50 g, 0.5–0.99 g, 1.00–1.99 g, 2.00–2.99 g, ≥3.00 g), and three successive harvests of the same plantlets. After each harvest, tubers were dired at room temperature (1 day), curred at 18 °C (13 days) and stored at 2 °C (540 days). Two kinds of storage losses were considered: (a) losses of entire tubers because of deterioration, and (b) fresh weight losses of the other tubers. Both kinds of losses were higher in cv. Liseta, in tubers with lower fresh weights and in tubers from the first harvest. Almost all minitubers ≥0.5 g from later harvests and from both cultivars survived storage for 1.5 years. Deterioration occurred mainly from 6 to 12 months of storage. Tubers which deteriorated during cold storage had already shown high weight losses during curing.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02361793
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  • 13
    Electronic Resource
    Electronic Resource
    Transmission and yield effects of a gibberellin mutant allele in potato (1993)
    Springer
    Potato research 36 (1993), S. 365-372 
    Details
    ISSN: 1871-4528
    Keywords: gametophytic selection ; reciprocal differences ; GA ; dwarfs ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A selected clone ofSolanum tuberosum Group Andigena PI 347773 (clone Adg 11.1) and the cultivar Superior had previously been shown to be heterozygous at a gibberellin related dwarfing locus, ga1. Experiments were conducted to test for gametophytic selection for alleles at the ga1 locus in reciprocal crosses and for the effect of genotype on tuber yield. The genotypes of individuals from superior-Adg 11.1 reciprocal F1 families were determined by test crossing. Genotypic classes could be distinguished by the percentages of dwarf seedlings in their test cross progeny. No differences were found in the genotypic distributions of the reciprocal families, which indicates gametophytic selection at this locus is not the cause of reciprocal yield differences. Superior-Adg 11.1 individuals classified by ga1 locus genotype were evaluated for tuber yield. Tuber yields were highly correlated with genotype in both reciprocal families. Yields followed the pattern of simplex〉duplex〉triplex, indicating that the recessive mutant ga1 allele exhibited a dose effect stimulating yield.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02361804
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  • 14
    Electronic Resource
    Electronic Resource
    Post-harvest characteristics of potato minitubers with different fresh weights and from different harvests. I. Dry-matter concentration and dormancy (1993)
    Springer
    Potato research 36 (1993), S. 265-272 
    Details
    ISSN: 1871-4528
    Keywords: Solanum tuberosum L. ; seed size ; rapid multiplication ; seed production ; non-destructive harvest ; cold treatment ; sprouting
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Dry-matter concentration and dormancy were studied in minitubers of cvs Agria and Liseta, using five fresh weight classes (〈0.50 g, 0.50–0.99 g, 1.00–1.99 g, 2.00–2.99 g and ≥3.00 g) and three successive harvests of the same plantlets. The average dry-matter concentration increased with tuber weight for tubers from the second and third harvests. In minitubers ≥0.5 g, dry-matter concentration was higher in tubers from later harvests. The dormant period (days from harvest to 50% sprouting) was longer in minitubers with lower than higher weights, and longer in tubers from the first harvest than from later harvests. A cold-storage period of 6 weeks, starting 14 days after harvest, reduced the dormant period by an average of 11 days.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02361792
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  • 15
    Electronic Resource
    Electronic Resource
    Effects of amino acids and glucose on the fry colour of potato crisps (1993)
    Springer
    Potato research 36 (1993), S. 359-364 
    Details
    ISSN: 1871-4528
    Keywords: glutamine ; arginine ; valine ; histidine ; asparagine ; proline ; tyrosine ; methionine mixture ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Amino acids and sugars were removed from slices of potato of the cultivar Record. The slices were then soaked in solutions of the amino acids and various concentrations of glucose to study their effect on the fry colour of crisps. Glutamine was an important amino acid in the development of fry colour intensity at low glucose concentrations and also contributed to the dark fry colour when combined with glucose concentrations above 0.15%. The basic amino acid arginine had a similar but lesser effect and other amino acids used gave the same effect at glucose concentrations above 0.45%. Asparagine could play an important role in the development of fry colour quality and may decrease the grey colour intensity developed by the mixture of amino acids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02361803
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  • 16
    Electronic Resource
    Electronic Resource
    Production of above-ground seed tubers on stem cuttings from eight potato cultivars (1993)
    Springer
    Potato research 36 (1993), S. 55-61 
    Details
    ISSN: 1871-4528
    Keywords: rapid multiplication ; Solanum tuberosum L. ; stem length ; underground tubers ; variability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The formation of above-ground tubers on stem cuttings of eight potato cultivars was studied over three seasons. To promote tuber formation in the leaf axils, stems grown from single node cuttings were exposed to short day conditions. Tuber formation underground was reduced by covering the soil with a plastic sheet and by using single node cuttings planted with the leaf axils several centimetres above the soil surface. With all cultivars except Alpha, which produced mis-shapen tubers in all experiments, an average of 11 (maximum 40) tubers per cutting were harvested. Significant cultivar × year interactions were observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02359834
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  • 17
    Electronic Resource
    Electronic Resource
    A simple assay system incorporating monoclonal antibodies for the detection of potato virus T (1993)
    Springer
    Potato research 36 (1993), S. 83-88 
    Details
    ISSN: 1871-4528
    Keywords: ELISA ; hybridoma ; closterovirus ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Two monoclonal antibodies (McAbs) which react specifically with potato virus T (PVT) were produced and tested for cross reactivity with potato viruses (A, S, X, Yo, YN, leaf roll), apple stem grooving virus (ASGV) and against healthy sap. They were found to be highly specific for PVT. These two McAbs form the basis of an enzyme-linked immunosorbent assay (ELISA) for the detection of PVT in infected plant material which is of key significance for potato quarantine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02358722
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  • 18
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    Acquisition of potato leafroll virus byMyzus persicae from secondarily-infected potato plants of different genotypes (1993)
    Springer
    Potato research 36 (1993), S. 89-96 
    Details
    ISSN: 1871-4528
    Keywords: ELISA ; enzyme amplification ; feeding behaviour ; field resistance ; honeydew excretion ; Myzus persicae ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The acquisition of potato leafroll virus (PLRV) byMyzus persicae nymphs from the top leaves of potato plants was studied throughout a growing season in relation to the antigen titre in those leaves and the feeding behaviour of the aphid. Secondarily-infected plants of eight potato genotypes with different levels of field resistance served as virus sources. Early in the growing season, plants were efficient sources for virus acquisition. The amount of viral antigen detected inM. persicae nymphs fed on the top leaves was strongly correlated with the titres of viral antigen in these leaves. Virus acquisition from the top leaves of older potato plants was markedly impaired and could not be correlated with their virus titre. With increasing age of the potato plants and the development of virus symptoms, the virus titre in the leaves declined and the initial weak correlation between the virus titre and field resistance ratings disappeared. Thus, screening secondarily-infected potato plants for field resistance to PLRV based on the concentration of viral antigen in leaves or in aphids fed on them should be avoided later in the growing season. The feeding rate ofM. persicae, measured by the number of honeydew droplets excreted, did not account for the reduced uptake of virus from older plants since it was not influenced by the age of the plant. Throughout the growing season, the feeding rate ofM. persicae nymphs on PLRV-infected plants was higher on genotypes with low levels of field resistance to PLRV than on genotypes with high ones.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02358723
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    Progeny testing for resistance to potato virus Y: a comparison of susceptible potato cultivars for use in testcrosses with resistant parents (1993)
    Springer
    Potato research 36 (1993), S. 327-333 
    Details
    ISSN: 1871-4528
    Keywords: PVY ; plant breeding ; progeny tests ; genetics ; resistance ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary For potato breeding or genetical research purposes, the number of copies of a dominant major gene for resistance to potato virus Y in a parent clone can be determined by test-crossing with a susceptible parent and observing the segregation ratio of resistant to susceptible seedlings in the progeny. In a comparison of different susceptible cultivars for use in test-crosses for this purpose, their progenies differed in the clarity of symptoms and parental phenotype proved an unreliable guide. Cvs Maris Piper, Arran Peak and Dr MacIntosh were found to be suitable tester parents, Pentland Squire less so and cv. Désirée was confirmed as having a major gene conferring incomplete resistance. It was found advisable to test-cross with more than one susceptible parent.
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    URL: http://dx.doi.org/10.1007/BF02361799
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    Effects of leaf blast on photosynthesis of rice. 1. Leaf photosynthesis (1993)
    Springer
    European journal of plant pathology 99 (1993), S. 197-203 
    Details
    ISSN: 1573-8469
    Keywords: Pyricularia ozyzae ; Oryza sativa ; respiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effect ofPyricularia oryzae, the causal organism of leaf blast in rice, on photosynthesis characteristics of rice leaves was measured in two greenhouse experiments. Leaf blast reduced photosynthesis not only through a reduction in green leaf area, but also through an effect on photosynthesis of green leaf tissue surrounding the lesions. The assimilation rate at light saturation (P max ) was more affected than the initial light use efficiency (∈). Dark respiration (R d ) increased as a result of infection. The experimental data were used to derive relations between leaf blast severity andP max , ∈ andR d .
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01974664
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  • 21
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    Effects of leaf blast on growth and production of a rice crop (1993)
    Springer
    European journal of plant pathology 99 (1993), S. 323-334 
    Details
    ISSN: 1573-8469
    Keywords: Pyricularia oryzae ; Oryza sativa ; crop loss
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Rice crops grown under irrigated conditions were inoculated withPyricularia oryzae during early growth stages to study the effect of leaf blast on yield formation. The inoculations led to severe epidemics of leaf blast around maximum tillering, characterized by the presence of typical blast lesions and an accelerated senescence of heavily infested leaf tissue. Leaf blast led to a prolonged tillering and a delay in flowering and maturity. Crop growth rate and leaf area formation declined sharply during establishment of the disease and continued to be reduced till maturity. This resulted in a marked reduction of total dry matter production and grain yield. Dry matter distribution was not affected. Leaf blast reduced spikelet number, 1000 grain weight, and the fraction filled grains. From this last observation it was concluded that the reduction in grain yield was exclusively source determined. Nitrogen uptake of the inoculated crops before flowering was reduced compared to the N uptake of the control crop, but shoot N content of the inoculated crops at flowering was higher. Uptake of nitrogen after flowering was negligible in both healthy and inoculated crops. Redistribution from vegetative tissue was therefore the main source of N for grain growth. The higher N content of the shoot organs in the inoculated crops during ripening led to the conclusion that the reduced N uptake was not responsible for the yield reduction observed. Consequently, the reduction in grain yield was solely determined by a reduced carbohydrate supply.
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    URL: http://dx.doi.org/10.1007/BF01974313
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    Effects of leaf blast on photosynthesis of rice 2. Canopy photosynthesis (1993)
    Springer
    European journal of plant pathology 99 (1993), S. 205-217 
    Details
    ISSN: 1573-8469
    Keywords: Pyricularia oryza ; Oryza sativa ; simulation model ; respiration ; vertical distribution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effect ofPyricularia oryzae, the causal organism of leaf blast in rice, on photosynthetic rate of a rice crop was determined with mobile equipment in the field. Canopy CO2 exchanges rate (CER) was significantly reduced in plots inoculated withP. oryzae. The experimentally obtained data were used to evaluate the performance of a model for the effects of leaf blast on canopy photosynthesis. The model comprised photosynthesis and respiration routines of a mechanistic crop growth model, extended with submodels for effects of leaf blast on both processes. Canopy photosynthesis and the effect of leaf blast on CER were accurately simulated with the model. Analysis showed that the reduction in canopy photosynthesis was mainly due to an adverse effect of lesions on leaf photosynthetic rate and to shading by dead leaf are resulting from disease induced senescence. A sensitivity analysis demonstrated the importance of the vertical distribution of the disease in the canopy. This implies that disease monitoring for crop loss assessment should consider vertical disease distribution.
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    URL: http://dx.doi.org/10.1007/BF01974665
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    Niacin, thiamin, and pantothenic acid bioavailability to humans from maize bran as affected by milling and particle size (1993)
    Springer
    Plant foods for human nutrition 43 (1993), S. 87-95 
    Details
    ISSN: 1573-9104
    Keywords: maize ; bran ; niacin ; thiamin ; pantothenic acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The objective of the project was to determine the bioavailability of selected B vitamins (niacin, pantothenic acid and thiamin) to humans from wet and dry milled maize brans which were coarsely or finely ground. Using a double cross-over design, the nine subjects were fed laboratory controlled diets containing unsupplemented bread or bread supplemented with finely ground, wet milled maize bran; coarsely ground, wet milled maize bran; finely ground, dry milled corn bran; or coarsely ground, dry milled maize bran. Subjects made complete collections of urine throughout the study which were analyzed for contents of the test vitamins. Although varying somewhat among vitamins, in general, better apparent bioavailability was achieved with the finely ground, dry milled maize bran than with the other test brans.
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    URL: http://dx.doi.org/10.1007/BF01088100
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    Mechanism of sugar retention by roots of intact maize and field bean plants (1993)
    Springer
    Plant and soil 155-156 (1993), S. 99-102 
    Details
    ISSN: 1573-5036
    Keywords: field bean ; maize ; plasmalemma ATPase ; proton motive force ; retrieval mechanism ; root exudates ; sugar/proton cotransport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The re-uptake of sugars driven by the proton gradient was studied in sugar net-release and net-uptake experiments using roots of intact maize (Zea mays cv. Blizzard) and field bean (Vicia faba L. cv. Alfred) plants. The net release of sugars into the root medium (0.1 mM CaSO4) was stimulated by: the protonophore CCCP (10 μM); the sulfhydryl reagent NEM (300 μM); the specific inhibitor of plasmalemma ATPase vanadate (0.5 mM); and the inhibitor of the glucose carrier phlorizin (2 mM). Net uptake of glucose, fructose and arabinose from 10 μM external concentrations was also inhibited by these substances. Surprisingly fusicoccin, a stimulator of net proton release did not effect net sugar uptake. Medium pH values only influenced sugar net uptake if the pH was above 7. It is concluded that a degradation of the proton gradient across the plasmalemma stimulates net sugar release because of disturbed re-uptake of sugars (in particular glucose) via a proton/sugar cotransport system. Thus, the retention of sugars by root cells not only depends on the plasmalemma permeability but also on the electro-chemical proton gradient. If an electro-chemical proton gradient is established by plasmalemma ATPase activity the re-uptake of sugars by proton/sugar cotransport minimizes the release of sugars into the rhizosphere.
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    URL: http://dx.doi.org/10.1007/BF00024993
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    Influx and efflux of amino acids from Zea mays L. roots and their implications for N nutrition and the rhizosphere (1993)
    Springer
    Plant and soil 155-156 (1993), S. 87-90 
    Details
    ISSN: 1573-5036
    Keywords: amino acids ; maize ; rhizosphere ; root exudates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The aim of the study was to investigate the ability of Zea mays L. roots to regulate the amount of free amino acids present in the rhizosphere. The active uptake of amino acids was shown to conform to Michaelis-Menten kinetics. Comparison of amino acid-N and NO3-N kinetic parameters and soil solution concentrations showed that root uptake of free amino acids from soil may contribute significantly to a plant's N budget. The influx of amino acids also helps to minimize net C/N losses to the soil, and is therefore important in regulating the size of the rhizosphere microbial population. Experimental data and a computer simulation model of amino acid influx/efflux in a sterile solution culture, showed that roots were capable of re-sorping over 90% of the amino acids previously lost into solution as a result of passive diffusion.
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    URL: http://dx.doi.org/10.1007/BF00024990
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    In-situ determination of the P-relations around the primary root of maize with respect to inorganic and phytate-P (1993)
    Springer
    Plant and soil 157 (1993), S. 1-9 
    Details
    ISSN: 1573-5036
    Keywords: autoradiography ; freeze-cutting ; maize ; P-accumulation ; P-depletion ; phytate-P
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Autoradiographs of soil slices mapping the distribution of phytate-derived33P around the primary root of 6-day-old maize seedlings were used to investigate the uptake of phytate by the root. Analysis of the autoradiographs with a laser densitometer and processing of the data with image analysing software resulted in a resolution of 40 μm. The effect of33P-crossfire was corrected by analysis of the apparent33P-gradient around a phosphate-impermeable teflon tube that was inserted into the labeled soil as a standard. In spite of the high resolution achieved, a significant depletion zone could not be detected when the soil was equilibrated with33P-phytate. However, with33P-inorganic phosphate, 2 concentric zones were obvious. Within the inner zone, P was accumulated by about 20%, while in the outer zone a corresponding depletion of P could be detected. The accumulation zone coincided with the extension of the root hair cylinder, whereas the depleted area was clearly beyond the range of the root hairs.
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    URL: http://dx.doi.org/10.1007/BF02390221
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    Inhibition of nitrate uptake by aluminium in maize (1993)
    Springer
    Plant and soil 151 (1993), S. 97-104 
    Details
    ISSN: 1573-5036
    Keywords: aluminium ; ammonium ; induction ; maize ; nitrate ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Experiments with two maize (Zea mays L.) hybrids were conducted to determine (a) if the inhibition of nitrate uptake by aluminium involved a restriction in the induction (synthesis/assemblage) of nitrate transporters, and (b) if the magnitude of the inhibition was affected by the concurrent presence of ambient ammonium. At pH 4.5, the rate of nitrate uptake from 240 μM NH4NO3 was maximally inhibited by 100 μM aluminium, but there was little measurable effect on the rate of ammonium uptake. Presence of ambient aluminium did not eliminate the characteristic induction pattern of nitrate uptake upon first exposure of nitrogen-depleted seedlings to that ion. Removal of ambient aluminium after six hours of induction resulted in recovery within 30 minutes to rates of nitrate uptake that were similar to those of plants induced in absence of aluminium. Addition of aluminium to plants that had been induced in absence of aluminium rapidly restricted the rate of nitrate uptake to the level of plants that had been induced in the presence of aluminium. The data are interpreted as indicating that aluminium inhibited the activity of nitrate transporters to a greater extent than the induction of those transporters. When aluminium was added at initiation of induction, the effect of ambient ammonium on development of the inhibition by aluminium differed between the two hybrids. The responses indicate a complex interaction between the aluminium and ammonium components of high acidity soils in their influence on nitrate uptake. ei]{gnA C}{fnBorstlap}
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    URL: http://dx.doi.org/10.1007/BF00010790
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    Nuclear magnetic resonance studies of the location and function of plant nutrients in vivo (1993)
    Springer
    Plant and soil 155-156 (1993), S. 45-55 
    Details
    ISSN: 1573-5036
    Keywords: compartmentation ; cytoplasm ; 39K NMR ; maize ; nitrogen ; 14N NMR ; 15N NMR ; pea ; phosphorus ; potassium ; 31P NMR ; vacuole
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The cytoplasmic and vacuolar pools of ammonium, inorganic phosphate and potassium can be studied non-invasively in plant tissues using high resolution nuclear magnetic resonance spectroscopy. The techniques that allow these pools to be discriminated in vivo are described and their application to plants is reviewed with reference to the phosphorus, nitrogen and potassium nutrition of root tissues.
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    URL: http://dx.doi.org/10.1007/BF00024983
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  • 29
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    In-situ determination of the P-relations around the primary root of maize with respect to inorganic and phytate-P (1993)
    Springer
    Plant and soil 157 (1993), S. 1-9 
    Details
    ISSN: 1573-5036
    Keywords: autoradiography ; freeze-cutting ; maize ; P-accumulation ; P-depletion ; phytate-P
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Autoradiographs of soil slices mapping the distribution of phytate-derived 33P around the primary root of 6-day-old maize seedlings were used to investigate the uptake of phytate by the root. Analysis of the autoradiographs with a laser densitometer and processing of the data with image analysing software resulted in a resolution of 40 μm. The effect of 33P-crossfire was corrected by analysis of the apparent 33P-gradient around a phosphate-impermeable teflon tube that was inserted into the labeled soil as a standard. In spite of the high resolution achieved, a significant depletion zone could not be detected when the soil was equilibrated with 33P-phytate. However, with 33P-inorganic phosphate, 2 concentric zones were obvious. Within the inner zone, P was accumulated by about 20%, while in the outer zone a corresponding depletion of P could be detected. The accumulation zone coincided with the extension of the root hair cylinder, whereas the depleted area was clearly beyond the range of the root hairs.
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    URL: http://dx.doi.org/10.1007/BF00038742
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    Effect of soil water content on the gravitropic behavior of nodal roots in maize (1993)
    Springer
    Plant and soil 152 (1993), S. 261-267 
    Details
    ISSN: 1573-5036
    Keywords: gravitropism ; growth angle ; maize ; nodal roots ; soil water content ; Zea mays L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The direction of root growth is an important factor that determines the spatial distribution of roots in the soil. The influence of soil water content on the direction of growth of maize nodal roots was studied both in the field and in the greenhouse. In the field experiment, the one plot was regularly irrigated (I-plot) and the other non-irrigated (N-plot). In the greenhouse experiment, three water treatments were conducted on plants grown in pots: continuously wet (CW), early drying (ED), and late drying (LD). The direction of root growth was quantified by the angle from the vertical, measured at 1 cm intervals for 10 cm from the first five internodes. Nodal roots grew more vertically in the N-plot and ED treatment than those in the I-plot and CW treatment. This was due to the decrease of the initial angle and/or the liminal angle. It is therefore thought that two events regulate the growth direction of nodal roots under dry soil conditions: gravitropic bending at root emergence from the stem and the later establishment of the angle of growth. Nodal roots appearing after rewatering in the ED treatment grew in a similar direction as those in the CW treatment. It follows from this that the water content of the surrounding soil has a direct effect on the direction of growth. Nodal roots that emerged in rapidly drying soil in the LD treatment ceased growing after showing negative gravitropism. The possible mechanisms determining the growth direction of nodal roots in drier soils are discussed.
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    URL: http://dx.doi.org/10.1007/BF00029096
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    Mulching effect of plant residues with chemically contrasting compositions on maize growth and nutrients accumulation (1993)
    Springer
    Plant and soil 153 (1993), S. 179-187 
    Details
    ISSN: 1573-5036
    Keywords: alfisols ; maize ; mulch quality ; nutrient uptake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Effects of application of prunings of three woody species (Acioa barteri, Gliricidia sepium and Leucaena leucocephala), maize (Zea mays L.) stover and rice (Oryza sativa L.) straw as mulch on maize were studied on an Alfisol in southern Nigeria in 1990 and 1991. Maize dry matter and grain yield were higher with applications of plant residues and N fertilizer in both years. Addition of Leucaena prunings gave the highest maize grain yield in both years. Compared to the 1990 results, Acioa showed the least grain yield decline among the mulch treatments in 1991. Nutrient uptake was enhanced by applications of plant residues. Leucaena prunings had the highest effect in both years and increased the mean N, P, and Mg uptake by 96%, 84%, and 50%, respectively, over the control. Addition of Acioa prunings increased K and Ca uptake by 59% and 92%, respectively, over the control. ‘High quality’ (low C/N ratio and lignin level) plant residues enhance crop performance through direct nutritional contributions, whereas ‘low quality’ (high C/N ratio and lignin level) plant residues do so through mulching effects on the microclimate. ‘Intermediate quality’ plant residues have no clear effects on crop performance.
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    URL: http://dx.doi.org/10.1007/BF00012990
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    The effect of phytase on the availability of P from myo-inositol hexaphosphate (phytate) for maize roots (1993)
    Springer
    Plant and soil 154 (1993), S. 189-196 
    Details
    ISSN: 1573-5036
    Keywords: bioavailability ; maize ; myo-inositol ; phosphorus ; phytase ; phytin ; soil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effect of adding phytase to the root medium of maize plants on the P-availability of added myo-inositol hexaphosphate (phytin) has been studied in pot experiments. When 40 mM phytin-P in nutrient solution was incubated in quartz-sand for 15 days in the absence of plants, 80% of it could be recovered from the solution as soluble organic P. Maize plants growing on this mixture assimilated P from phytin at rates comparable to those from inorganic phosphate (Pi). At a lower addition rate (2 mM phytin-P) only 10% was recovered in the soil solution, and plant growth was severely limited by P. At this low phytin level, the addition of phytase (10 enzyme units per kg sand) increased the plants' dry weight yield by 32%. The relative increases of the Pi concentration in the solution and of the amount of P in the plants were even higher, indicating that the observed growth stimulation was due to an increased rate of phytin hydrolysis. The enzyme-induced growth stimulation was also observed with plants growing in pots filled with soil low in P, when phytin was added. However, on three different soils the addition rates of phytin and phytase necessary for obtaining a significant phytase effect were both about 10 times higher than those required in quartzsand. It is concluded that the P-availability from organic sources can be limited by the rate of their hydrolytic cleavage.
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    URL: http://dx.doi.org/10.1007/BF00012524
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    Determination of critical temperatures and panicle development stage for fertility change of thermo-sensitive genic male sterile rice line ‘5460S’ (1993)
    Springer
    Euphytica 67 (1993), S. 27-33 
    Details
    ISSN: 1573-5060
    Keywords: Oryza sativa ; thermo-sensitive genic male sterile rice (TGMSR) ; critical temperature ; sensitive panicle development stage ; fertility change
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The effect of a 1–5 day low temperature treatment applied at different stages during panicle development on the male sterility of 5460S, a thermo-sensitive genic male sterile rice line (TGMSR), was studied. Before and after the period of low temperature treatments the plants were continuously grown under 14.75 h daylength and 29.6° C average temperature (max. 33° C/min. 29° C) in growth chambers in order to avoid any other possible influences on the male sterility. The results indicate that the plant responses to low temperature was dependant on the developmental stage of the young panicle. The stages from formation of pollen mother cell to late uninucleate of pollen grains were the most sensitive to temperature. It is concluded that the critical temperature for the fertility change from male sterile to partially fertile in ‘5460S’ is about 28.5° C in the sensitive panicle development stages under the condition studied.
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    URL: http://dx.doi.org/10.1007/BF00022721
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    Genotype selection via a new yield-stability statistic in maize yield trials (1993)
    Springer
    Euphytica 70 (1993), S. 105-111 
    Details
    ISSN: 1573-5060
    Keywords: maize ; genotype × environment interaction ; stability analysis ; cultivar testing ; YSi statistic ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Genotype × environment (GE) interaction complicates selection of superior genotypes across environments. The main objective of this study was to select maize (Zea mays L.) genotypes via a new yield-stability (YSi) statistic in yield trials conducted in Albania. Another objective was to estimate contribution of environmental index (% MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGak0dh9WrFfpC0xh9vqqj-hEeeu0xXdbba9frFj0-OqFf% ea0dXdd9vqaq-JfrVkFHe9pgea0dXdar-Jb9hs0dXdbPYxe9vr0-vr% 0-vqpWqaaeaabaGaaiaacaqabeaadaqaaqaaaOqaaiqadIfagaqeaa% aa!3851!\[\bar X\]·j − % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGak0dh9WrFfpC0xh9vqqj-hEeeu0xXdbba9frFj0-OqFf% ea0dXdd9vqaq-JfrVkFHe9pgea0dXdar-Jb9hs0dXdbPYxe9vr0-vr% 0-vqpWqaaeaabaGaaiaacaqabeaadaqaaqaaaOqaaiqadIfagaqeaa% aa!3851!\[\bar X\].., where % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGak0dh9WrFfpC0xh9vqqj-hEeeu0xXdbba9frFj0-OqFf% ea0dXdd9vqaq-JfrVkFHe9pgea0dXdar-Jb9hs0dXdbPYxe9vr0-vr% 0-vqpWqaaeaabaGaaiaacaqabeaadaqaaqaaaOqaaiqadIfagaqeaa% aa!3851!\[\bar X\]·j is mean of all genotypes in the jth environment and % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGak0dh9WrFfpC0xh9vqqj-hEeeu0xXdbba9frFj0-OqFf% ea0dXdd9vqaq-JfrVkFHe9pgea0dXdar-Jb9hs0dXdbPYxe9vr0-vr% 0-vqpWqaaeaabaGaaiaacaqabeaadaqaaqaaaOqaaiqadIfagaqeaa% aa!3851!\[\bar X\]is mean of all genotypes across all environments), minimum temperature, maximum temperature, preseason rainfall, rainfall during the growing season, and relative humidity to GE interaction by determining heterogeneity (nonadditivity) attributable to each of these environmental factors. In five of eight trials, heterogeneity due to environmental index was significant. Heterogeneity due to the other environmental factors was not significant in any trial. A comparison of δ i 2 (stability-variance statistic derived from total GE interaction) and s i 2 (stability-variance statistic derived from residual GE interaction following removal of heterogeneity due to encovariate) helped identify genotypes that performed stably or unstably because of a linear effect of environmental index. In three of the five trials showing significant heterogeneity due to environmental index, the YSi statistic selected a reduced number of unstable genotypes as compared with selection based solely on yield. However, the circumstances or conditions under which YSi and solely yield-based method select the same or different genotypes are not fully understood.
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    URL: http://dx.doi.org/10.1007/BF00029647
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    Cytochemical investigation of long-term stored maize pollen (1993)
    Springer
    Euphytica 72 (1993), S. 87-94 
    Details
    ISSN: 1573-5060
    Keywords: Zea mays ; maize ; pollen storage ; pollen grain viability ; pollen enzymes ; pollen physiology ; enzyme cytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Maize pollen quality was investigated after long-term storage both in a refrigerator and in liquid nitrogen by a combination of viability tests and cytochemical methods. Determination of the activities of a number of enzymes involved in important metabolic pathways was carried out. Quinone formation was also studied, as some products of secondary metabolism affect pollen grain viability. One year of pollen storage in liquid nitrogen had little effect on the activities of oxidoreductases and hydrolases and had no significant effect on pollen grain viability evaluated by acetocarmine, neutral red and acridine organe. Only the FCR test showed slightly decreased viability. After one and two years of storage in a refrigerator, pollen grain viability, tested using acetocarmine, neutral red and acridine orange, did not change substantially. Simultaneously the FCR test showed a considerable decrease in pollen grain viability. Long-term storage in a refrigerator resulted in the loss of cytochrome oxidase activity and rise of alcohol dehydrogenase, lactate dehydrogenase, peroxidase and polyphenoloxidase activities as well as of quinone formation.
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    URL: http://dx.doi.org/10.1007/BF00023776
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    Gas-filled root porosity in response to temporary low oxygen supply in different growth stages (1993)
    Springer
    Plant and soil 152 (1993), S. 187-199 
    Details
    ISSN: 1573-5036
    Keywords: aeration ; aerenchyma ; carnation ; cucumber ; gerbera ; maize ; oxygen stress ; oxygen transport ; redox dye ; rice ; rose ; sugar beet ; sweet pepper ; tomato ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The development of gas-filled root porosity in response to temporary low oxygen supply was tested for a range of edible and ornamental crops: rice, maize, wheat, sugar beet, tomato, cucumber, sweet pepper, carnation, gerbera and rose. In a first experiment, the roots of tomato, maize and gerbera had a higher gas-filled root porosity, Ep (% v/v), when grown permanently in a non-aerated instead of aerated solution. The Ep of roots increased during two weeks when half the root system of a young plant was transferred to a non-aerated solution; in older plants this response was not seen. Carnation had a negligible gas-filled porosity in all treatments. In a second experiment, a comparison was made between high (20 kPa) and low (about 2 kPa) O2 partial pressure in a recirculating nutrient solution. Half of the root system was transferred to low O2 at various growth stages. In most species older plants did not increase Ep on exposure to low O2. For tomato, sweet pepper and rose, Ep was normally in the range 3–8% (v/v). Young plants of cucumber, wheat and sugar beet also had an Ep in that range, but in older plants values ranged from 1 to 3%. Transverse root sections examined by light microscopy showed, on average, 60% more intercellular spaces in the root cortex than the measurements of gas-filled porosity, probably because some gaps and spaces in the cortex were not gas-filled. This effect was most pronounced in tomato. A negative pressure in the cortex may be needed for gaps to be gas-filled. An exodermis may increase the effectiveness of gas spaces in the cortex by closing the gas channels and, by offering some resistance to water uptake, allowing a negative pressure head in the cortex which keeps gaps gas-filled. A redox dye method was developed to study the length of root which is effectively supplied with oxygen, as a function of Ep. Results indicated that for every percent Ep the root can remain aerated over at least 1 cm in a non-aerated medium under the conditions of the test.
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    URL: http://dx.doi.org/10.1007/BF00029088
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    Effects of fertilization levels in two farming systems on senescence and nutrient contents in potato leaves (1993)
    Springer
    Plant and soil 154 (1993), S. 81-88 
    Details
    ISSN: 1573-5036
    Keywords: farming system ; fertilization ; magnesium ; nitrogen ; potassium ; potato ; proteolytic enzymes ; senescence ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The influence of fertilization on senescence and nutrient remobilization in potato leaves was investigated in two farming systems on a soil with a poor potassium availability. The ‘Conventional’ farming system followed good local practices including industrial products, while in the ‘Bio-Dynamic’ farming system industrial fertilizers and synthetic pesticides were avoided. Potassium concentrations in the dry matter of mature leaves varied over a wide range. Nitrogen compounds (protein, chlorophyll) were less affected, and phosphorus concentrations in the dry matter were similar. Magnesium and potassium concentrations in the leaves were negatively correlated. In both farming systems senescence was advanced in plants with a low nutrient supply. Alkaline pyrophosphatase and aminopeptidase activities (in general highest in expanding and mature leaves) were lower and endopeptidase activities peaked earlier on plots with low fertilizer levels. A high percentage of potassium was remobilized from senescing leaves on unfertilized plots, but the phosphorus concentration remained high at the end of the season. The results suggest that the differential net remobilization of nitrogen, phosphorus and potassium depended on actual source/sink relations in the plants.
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    URL: http://dx.doi.org/10.1007/BF00011075
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    Differences between maize and wheat in growth-related nutrient demand and uptake of potassium and phosphorus at suboptimal root zone temperatures (1993)
    Springer
    Plant and soil 150 (1993), S. 129-138 
    Details
    ISSN: 1573-5036
    Keywords: adaptation ; maize ; nutrient uptake ; root growth ; root temperature ; shoot base temperature ; shoot growth ; shoot demand per unit of roots ; spring wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of low root zone temperatures (RZT) on nutrient demand for growth and the capacity for nutrient acquisition were compared in maize and wheat growing in nutrient solution. To differentiate between direct temperature effects on nutrient uptake and indirect effects via an altered ratio of shoot to root growth, the plants were grown with their shoot base including apical shoot meristem either within the root zone (low SB), i.e. at RZT (12°, 16°, or 20°C) or, above the root zone (high SB), i.e. at uniformly high air temperature (20°/16° day/night). At low SB, suboptimal RZT reduced shoot growth more than root growth in wheat, whereas the opposite was true in maize. However, in both species the shoot growth rate per unit weight of roots, which was taken as parameter for the shoot demand for mineral nutrients per unit of roots, decreased at low RZT. Accordingly, the concentrations of potassium (K) and phosphorus (P) remained constant or even increased at low RZT despite reduced uptake rates. At high SB, shoot growth at low RZT in both species was higher than at low SB, whereas root growth was not increased. At high SB, the shoot demand per unit of roots was similar for all RZT in wheat, but increased with decreasing RZT in maize. Uptake rates of K at high SB and low RZT adapted to shoot demand within four days, and were even higher in maize than in wheat. Uptake rates of P adapted more slowly to shoot demand in both species, resulting in reduced concentrations of P in the shoot, particularly in maize. In conclusion, the two species did not markedly differ in their physiological capacity for uptake of K and P at low RZT. However, maize had a lower ability than wheat to adapt morphologically to suboptimal RZT by increasing biomass allocation towards the roots. This may cause a greater susceptibility of maize to nutrient deficiency, particularly if the temperatures around the shoot base are high and uptake is limited by nutrient transport processes in the soil towards the roots.
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    URL: http://dx.doi.org/10.1007/BF00779183
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    Nitrogen cycling in leucaena (Leucaena leucocephala) alley cropping in semi-arid tropics (1993)
    Springer
    Plant and soil 148 (1993), S. 63-72 
    Details
    ISSN: 1573-5036
    Keywords: alley cropping ; C/N ratio ; decomposition ; fertilizer N ; leucaena N ; leucaena residues ; lignin ; maize ; N mineralization ; 15N recovery ; N uptake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The success of alley cropping depends to a large extent on the efficiency of transfer of nitrogen (N) from the legume hedgerow plants to the non-legume crop. Here the idea is examined that leucaena prunings (residues) can supply enough N to maize plants to significantly reduce the degree of N deficiency. Two experiments on decomposition of leucaena leaf, stem, and petiole and mineralization of N from leucaena residues were conducted in field microplots which received application of either15N-labelled leucaena materials or ammonium sulphate fertilizer. The microplots were installed in alleys formed by leucaena hedgerows spaced 4.5 metres apart and cropped with maize. The decomposition of leucaena leaves, stems and petioles was estimated by several methods. The decomposition ranged from 50–58% with leaves, 25–67% with stems and 38–51% with petioles 20 days after addition. More than 55% of the N was released in 52 days during decomposition of leucaena residues. By 20 days after application of15N-labelled leucaena 3.3–9.4% of the added15N was found in the maize plants, 32.7–49.0% was in the leucaena residues, 36.0–48.0% in the soil and 0.3–21.9% lost (deficit). By 52 days 4.8% of the15N applied in leucaena prunings was taken up by maize, 45.1% was detected in the residues, 24.9% in the soil and 25.2% lost. However, when N fertilizer was applied, 50.2% of the fertilizer N was recovered by maize, 35.5% was retained in the soil and 14.3% apparently lost. There was a marked increase in maize plant dry matter and N uptake in the microplots with addition of leucaena prunings compared with those in the microplots without leucaena added. Most of the15N remaining in the soil profile, derived from leucaena residues, was detected in the top 25 cm soil with less than 2% found below 25 cm. ei]H Lambers
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    URL: http://dx.doi.org/10.1007/BF02185385
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    Nutrient fluxes in the shifting cultivation system of south-west Côte d'Ivoire (1993)
    Springer
    Plant and soil 154 (1993), S. 179-188 
    Details
    ISSN: 1573-5036
    Keywords: ash ; burning ; Côte d'Ivoire ; efficiency of utilization of nutrients ; maize ; nutrient uptake ; residual effects ; shifting cultivation ; Taï National Park ; upland rice ; weed growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract At two sites, one with a 4-year-old (4-Y) secondary vegetation and the other with a 20-year-old (20-Y) vegetation, the influence of burning slashed vegetation on crop performance was studied during three seasons. In the first season after clearing, also the influence on weed growth was studied. At both sites, burning significantly decreased the number of weed seedlings. The lowest number of seedlings was found on the burnt plots of the 20-Y site. Burning increased yield and nutrient uptake significantly in the first and second season after clearing. In the third season after burning, only at the 4-Y site a significantly higher yield and nutrient uptake were found. At the 20-Y site the effect had disappeared. Calculations of efficiency of utilization of absorbed N, P and K indicated that P was the least available nutrient, also after burning. At both sites three consecutive crops absorbed approximately 40% of P applied in ash, while the cumulative recovery of K was at least 36% at the 4-Y site and at least 59% at the 20-Y site. On non-burnt plots, yields were not lower in the third season than in the first season after clearing, thus indicating that the inherent soil fertility did not decrease. Hence, yield decline on the burnt plots could be ascribed to ash depletion. It was concluded that in the local shifting cultivation system, the combination of ash depletion and infestation of weeds are the main reasons for abandoning the fields.
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    URL: http://dx.doi.org/10.1007/BF00012523
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    Inhibition of mitochondrial electron transport is the prime cause behind proline accumulation during mineral deficiency in Oryza sativa (1993)
    Springer
    Plant and soil 155-156 (1993), S. 465-468 
    Details
    ISSN: 1573-5036
    Keywords: iron ; mineral deficiency ; mitochondrial electron transport ; NADH ; Oryza sativa ; proline
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The concentration of proline in shoots of rice (Oryza sativa) seedlings raised in distilled water was about 3.3 times higher than in the seedlings raised in modified B5 medium. The shoots of seedlings raised in B5 medium which was depleted of calcium, iron, magnesium or potassium had a higher concentration of proline than those grown in standard B5 medium. The shoots of seedlings raised in distilled water with iron had a lower level of proline than those in distilled water. These results suggest that iron deficiency leads to high proline accumulation. The electron transport activity of mitochondria from shoots of etiolated seedlings raised in distilled water or iron-depleted B5 medium was significantly lower than those from equivalent seedlings raised with an iron source. As suppression in mitochondrial electron transport leads to an increase in NADH/NAD+ ratio, we propose that the prime cause of the proline accumulation during iron deficiency is to readily maintain NADH/NAD+ ratio.
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    URL: http://dx.doi.org/10.1007/BF00025084
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    Osmotic stress and water stress have opposite effects on putrescine and proline production in excised rice leaves (1993)
    Springer
    Plant growth regulation 13 (1993), S. 197-202 
    Details
    ISSN: 1573-5087
    Keywords: abscisic acid ; jasmonic acid methyl ester ; Oryza sativa ; osmotic stress ; proline ; putrescine ; water stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of water stress and osmotic stress (sorbitol treatment) on the production of putrescine and proline in excised rice leaves were compared. Osmotic stress and water stress were found to affect differentially the levels of putrescine and proline in excised rice leaves. Putrescine accumulation is induced by osmotic stress, whereas proline accumulation is induced by water stress. The effects of ABA on the levels of proline and putrescine are similar to those of water stress, whereas the effects of jasmonic acid methyl ester (JA-Me) are similar to those of osmotic stress. Water stress results in an increase of endogenous ABA is excised rice leaves. However, neither osmotic stress nor JA-Me has effect on endogenous ABA levels in excised rice leaves. Of particular interest is the finding that proline levels increase when putrescine levels induced by osmotic stress or JA-Me are reduced by D-arginine and α-methylornithine. L-arginine and L-ornithine applied exogenously also cause an increase in proline levels. It seems that L-arginine and L-ornithine are preferentially utilized as precursors for putrescine accumulation in excised rice leaves treated with osmotic stress and JA-Me, and for proline accumulation in excised rice leaves exposed to water stress and ABA.
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    URL: http://dx.doi.org/10.1007/BF00024262
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    Changes in putrescine accumulation induced by agents affecting cytosolic pH in detached rice leaves (1993)
    Springer
    Plant growth regulation 13 (1993), S. 133-136 
    Details
    ISSN: 1573-5087
    Keywords: cytosolic pH ; Oryza sativa ; putrescine ; rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Effects of compounds that influenced cytosolic pH on the level of putrescine in detached rice leaves were examined. Permeant weak acids, isobutyric acid and propionic acid, increased the level of putrescine in detached rice leaves. Procaine and trisodium citrate, known to be permeant weak bases, on the other hand, decreased the level of putrescine. It seems possible that the level of putrescine in detached rice leaves is regulated by the cytosolic pH.
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    Salicylic acid inhibits the biosynthesis of ethylene in detached rice leaves (1993)
    Springer
    Plant growth regulation 12 (1993), S. 79-82 
    Details
    ISSN: 1573-5087
    Keywords: ethylene biosynthesis ; salicylic acid ; Oryza sativa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of salicylic acid (SA) on ethylene biosynthesis in detached rice leaves were investigated. SA at pH 3.5 effectively inhibited ethylene production within 2 h of its application. It inhibited the conversion of ACC to ethylene, but did not affect the levels of ACC and conjugated ACC. Thus, the inhibitory effect of SA resulted from the inhibition of both synthesis of ACC and the conversion of ACC to ethylene.
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    URL: http://dx.doi.org/10.1007/BF00144586
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    Nitrogen fertilizer in leucaena alley cropping. II. residual value of nitrogen fertilizer and leucaena residues (1993)
    Springer
    Nutrient cycling in agroecosystems 34 (1993), S. 1-8 
    Details
    ISSN: 1573-0867
    Keywords: leucaena ; maize ; 15N recovery ; residual15N
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Legume residues have been credited with supplying mineral nitrogen (N) to the associated cereal crop and improving soil fertility in the long term. Few studies using15N have reported the fate of legume N and fertilizer N in the presence of legume residues in soil-plant systems over periods of two years or longer. A field experiment was conducted in microplots to evaluate: (1) the residual value of the15N added in leucaena residues; (2) the residual value of fertilizer15N applied in the presence of unlabelled leucaena residues in the first year to maize over three subsequent years; and (3) the long-term fate of residual fertilizer and leucaena15N in a leucaena alley cropping system. There was a significant increase in maize production over three subsequent years after addition of leucaena residues. The residual effect of fertilizer N increased maize yield in the second year when N fertilizer was applied at 36 kg N ha−1 in the first year in the presence of leucaena residues. Of the leucaena15N applied in the first year, the second, third and fourth maize crop recovered 2.6%, 1.8% and 1.4%, respectively. The corresponding values for the residual fertilizer15N were 0.7%, 0.4% and 0.3%. About 12–14% of the fertilizer15N added in the first year was found in the 200 cm soil profile over the following three years. This differed from the 38–41% of leucaena15N detected in the soil over the same period. Most of the residual fertilizer and leucaena15N in the soil was immobilized in the top 25 cm with less than 1% leached below 100 cm. More than 36% of the leucaena15N and fertilizer15N added in the first year was apparently lost from the soil-plant system in the first two years. No further loss of the residual leucaena and fertilizer15N was detected after two years.
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    URL: http://dx.doi.org/10.1007/BF00749953
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    The effect of feeding maize husk and leucaena mixed or separately on the voluntary intake of the husk (1993)
    Springer
    Agroforestry systems 24 (1993), S. 271-276 
    Details
    ISSN: 1572-9680
    Keywords: intake ; maize ; husk ; leucaena ; goats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effect of feeding maize (Zea mays L.) husk and leucaena (Leucaena leucocephala) as a mixture or separately on the voluntary intake of maize husk was studied over a 40-day period. Ten male goats with an average weight of 15 kg were used. The maize husk intake and total dry matter intake for the two feeding methods was about the same. Thus, total dry matter intake was not affected (P〈0.05) by the feeding method. There was also no significant difference (P〈0.05) between the two feeding methods in the digestibility values. The data were considered to indicate that there were no significant differences in the intake of maize husk when fed in a mixture with leucaena or when offered separately but at the same time.
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    Use of the SCUAF model to simulate natural miombo woodland and maize monoculture ecosystems in Zimbabwe (1993)
    Springer
    Agroforestry systems 22 (1993), S. 259-271 
    Details
    ISSN: 1572-9680
    Keywords: SCUAF ; computer model ; soil carbon ; soil nitrogen ; miombo ; maize
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract ‘Soil Changes Under Agroforestry’ (SCUAF), a computer model designed to predict changes in erosion, soil carbon and soil nitrogen over time within various agroforestry systems and climatic regimes, was assessed using input data from an undisturbed miombo woodland and an adjacent maize field in Zimbabwe. Predicted changes in soil carbon were in a realistic range for both miombo and maize treatments. However, the accuracy of the model may be a reflection of the detail required in its initialisation. Several problematic relationships were found within the model, in particular inconsistent patterns between nitrogen uptake and plant productivity under complex fertilisation simulations and a lack of attenuation of productivity in the simulation of miombo woodland as it approached maturity.
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    URL: http://dx.doi.org/10.1007/BF00705238
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    A study of alley-cropping data from Northern Brazil. I. Distributional properties (1993)
    Springer
    Agroforestry systems 22 (1993), S. 241-258 
    Details
    ISSN: 1572-9680
    Keywords: agroforestry ; Inga edulis ; maize ; beans ; statistical analysis ; distributions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Measurements from trees and plants of a BrazilianInga/maize/beans alleycrop experiment were assessed for their distributional properties for three years of the study. Results for the tree data were similar to those found in an earlier study. Results for the crop data demonstrated similarities between the distributions for alleycrops and solecrops, nonnormality shown by positive skewness and peaked distributions. Changes in the distributional shapes were demonstrated from year to year as soil nutrient depletion increased and as climatic variables fluctuated. Variation across the rows in the alley was often of a similar size to variation from plant to plant within the rows. Initial recommendations for analysis of such data are given on the basis of these results.
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    URL: http://dx.doi.org/10.1007/BF00705237
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    Combination of stem elongation ability with submergence tolerance in rice (1993)
    Springer
    Euphytica 68 (1993), S. 11-16 
    Details
    ISSN: 1573-5060
    Keywords: deepwater rice ; elongation ability ; Oryza sativa ; submergence tolerance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A study was conducted with six F2 populations to test the possibility of combining submergence tolerance and stem elongation ability into a single genotype of rice (Oryza sativa L.). Submergence tolerance and stem elongation ability could be combined in the same genotype if strongly submergence tolerant genes are present in submergence tolerant parents.
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    Latent period to leaf blast in rice and its importance as a component of partial resistance (1993)
    Springer
    Euphytica 69 (1993), S. 185-190 
    Details
    ISSN: 1573-5060
    Keywords: leaf blast ; Magnaporthe grisea ; Oryza sativa ; partial resistance ; Pyricularia oryzae ; rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary In many pathosystems, a prolonged latent period is an important component of partial resistance. Latent period in rice to leaf blast was assessed in cultivars representing a fairly wide range of partial resistance under various conditions that are known to influence the expression of partial resistance considerably. The latent period was slightly more than four days and varied only little between treatments, with a maximum difference of only eight hours between cultivars. The very small differences in latent period were not associated with differences in partial resistance due to cultivar, nitrogen, or leaf age effects. It was concluded that the latent period is of no importance as a component of partial resistance to leaf blast.
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    URL: http://dx.doi.org/10.1007/BF00022364
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    Genetic analysis of mesocotyl length and its relationship with other agronomic characters in rice (Oryza sativa L.) (1993)
    Springer
    Euphytica 72 (1993), S. 189-195 
    Details
    ISSN: 1573-5060
    Keywords: mesocotyl ; diallel cross ; rice ; Oryza sativa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Mesocotyl length is an important character in promoting seedling emergence of direct-seeded rice. Genetic analysis of rice mesocotyl length was conducted using a six parent diallel cross. Generation mean analysis was carried out on parents (P), F1, F2 and backcrosses (B) of three crosses to complement the genetic information from the diallel analysis. Both analyses demonstrated the presence of significant additive and dominance effects. Duplicate type of non-allelic interaction was detected by the generation mean analysis and two crosses showed significant negative dominance gene effect. Dominance was partial and the narrow sense heritability estimate for mesocotyl length was high, indicating the preponderance of the additive effects. Mesocotyl length was negatively but weakly correlated with the coleoptile length and length of the second internode L2. There was no correlation between mesocotyl length and other mature plant characters such as plant height and internode lengths L1, (L1 being the peduncle with subsequent internodes to the base of the plant). Selection for mesocotyl length can therefore be carried out independent of these plant characters and semidwarf rice varieties with long mesocotyl can be developed.
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    URL: http://dx.doi.org/10.1007/BF00034157
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    Analysis of dihaploid induction and production ability and seed parent x pollinator interaction in potato (1993)
    Springer
    Euphytica 72 (1993), S. 61-64 
    Details
    ISSN: 1573-5060
    Keywords: dihaploid potato induction ; pseudogamy ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The production of dihaploids is the first step in a potato breeding program at the diploid level. Dihaploid induction ability, dihaploid production ability and seed parent x pollinator interaction were analyzed for 28 × 3, seed parent x pollinator combinations. This is the first report on significant interaction between seed parents and pollinators. Despite this interaction, IVP 101 had a significantly higher dihaploid induction ability than the widely used pollinators IVP 35 and IVP 48. Previous findings on significant differences in dihaploid production ability between seed parents were clearly confirmed.
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    Mid-parent heterosis and combining ability of European corn borer resistance in maize (1993)
    Springer
    Euphytica 72 (1993), S. 65-72 
    Details
    ISSN: 1573-5060
    Keywords: diallel analysis ; host plant resistance ; Ostrinia nubilalis ; plant breeding ; Zea mays ; maize ; European corn borer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Success in breeding maize resistant to the European corn borer has been limited, with the exception of leaf feeding resistance. The inheritance of resistance to leaf, sheath-collar and ear damage in four maize germplasms and their six F1 crosses was evaluated by diallel analysis. Plants in a completely randomized design were artificially infested at the whorl, anthesis or full silk stage of plant development and were evaluated in the field for insect damage. A damage index based on size, number and location of lesions was calculated for each stage. Stowell's Evergreen (susceptible) had a mean damage index three to six times that of Maiz Amargo (resistant) at the whorl stage and the progeny plants were more resistant than the susceptible parent. Maiz Amargo and its crosses had significantly lower mean indices than Stowell's Evergreen for sheath-collar damage in Year 1 but not Year 2. Zapalote Chico, Maiz Amargo and their cross were significantly less damaged than other genotypes at the full silk stage. Heterosis values indicated an increase in resistance of crosses over the midparent average at all three stages of development. General combining ability (GCA) was highly significant for all types of damage, but specific combining ability was significant only for leaf damage. Based on estimates of GCA, Maiz Amargo was the best source of resistance to leaf and sheath-collar damage and both Zapalote Chico and Maiz Amargo would be good parents for ear damage resistance. Results suggest that resistance at different plant development stages can be combined.
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    URL: http://dx.doi.org/10.1007/BF00023774
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    Nutritional disorders between potassium, magnesium, calcium, and phosphorus in soil (1993)
    Springer
    Plant and soil 154 (1993), S. 21-28 
    Details
    ISSN: 1573-5036
    Keywords: activity ratio ; ammonium phosphate ; chloride ; maize ; sandy loam ; soil extracts ; sulphate ; superphosphate ; unbalanced nutrition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A new soil testing procedure has been used to demonstrate the effect of an overfertilization by potassium during the preceding years. The total concentration of cations was governed by the amount of soluble anions and the proportion between the different cations was dependent on exchange reactions and is described by activity ratio. High activity ratio between potassium and calcium induced Ca-deficiency, which resulted in a restricted root functioning shown by periodic decreases of nutrient uptake rates and plant growth rate. P-deficiency restricted root growth, but although ammonium phosphate was most effective to increase P-concentration in soil extracts and P-absorption by plants, ordinary superphosphate gave the highest yield and the best utilization of the absorbed phosphorus, magnesium, and calcium.
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    URL: http://dx.doi.org/10.1007/BF00011066
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    Variability in nitrogen fixation of common bean (Phaseolus vulgaris L.) intercropped with maize (1993)
    Springer
    Plant and soil 152 (1993), S. 93-101 
    Details
    ISSN: 1573-5036
    Keywords: common bean ; maize ; intercropping ; nitrogen fixation ; 15N isotope ; 15N natural variation ; Rhizobium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Thirty one selected bean lines were evaluated in the field for ability to support N2 fixation when intercropped with maize which received 0, 30 and 60 kg N ha−1 as ammonium sulphate. The amount of fixed N2 was estimated using the natural variation of 15N and wheat as the standard non-fixing crop. Nitrogen as low as 15 kg N ha−1 at sowing suppressed nodule weight and activity (acetylene reduction activity) but not nodule number, suggesting that the main effect of mineral N was on nodule development and function. 15N data revealed a high potential of the bean genotypes to fix N2, with the most promising ones averaging between 50–60% of seed N coming from fixation. Bean lines CNF-480, Puebla-152, Mexico-309, Negro Argel, CNF-178, Venezuela-350 and WBR22-3, WBR22-50 and WBR22-55 were ranked as good fixers.
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    Re-sorption of organic compounds by roots of Zea mays L. and its consequences in the rhizosphere (1993)
    Springer
    Plant and soil 153 (1993), S. 47-59 
    Details
    ISSN: 1573-5036
    Keywords: maize ; mathematical model ; re-sorption ; rhizosphere ; root exudates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The exudation of soluble carbon compounds from Zea mays roots was investigated over a 10 day growth period under sterile and non-sterile solution culture conditions. The results showed that plants grown in sterile static solution culture, where C was allowed to accumulate, released 8 times less C than plants grown under culture conditions in which the solutions were replaced daily. The increased C loss from plant cultures in which exudates were removed daily was attributable to, (a) the reduced potential for root re-sorption of previously lost C, and (b), increasing diffusion gradients between the root and the surrounding bathing solution increasing passive leakage of exudates from the roots. In treatments where C was removed daily from the root-bathing solution, 86% of the total C lost was of a soluble low molecular weight nature, whereas, in sterile and non-sterile static cultures, allowing the accumulation of C over 10 days, this was reduced to 67.5 and 48% respectively. The main C fluxes operating in a solution culture system (efflux and influx of C by both roots and microorganisms) were examined using a computer simulation model to describe movement of soluble sugar-C in both sterile and non-sterile conditions. In sterile static cultures where C was allowed to accumulate in solution over a 10 day growth period, 98% of the C exuded was re-absorbed by the plant. Where C was removed daily from the root-bathing solution this was reduced to 86%. The predicted patterns of C accumulation were similar to those found in the experiments. Simulations showed that the pattern of accumulation and final equilibrium concentrations were dependent on the rate of exudation, the spatial characteristics of exudation, solution volume, root growth rate and the presence of a microbial population. Simulations under non-sterile conditions showed that roots can compete with microorganisms for exudates in solution indicating the possible importance of re-sorption in a soil environment. The results clearly indicate that roots are capable of regulating the net amount of C released into a solution culture with the amount of C collected being highly dependent on the experimental conditions employed. The possible implications of soluble C influx on processes operating within the rhizosphere and in experimental systems is discussed.
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    URL: http://dx.doi.org/10.1007/BF00010543
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    Estimates of the residual nitrogen benefit of groundnut to maize in Northeast Thailand (1993)
    Springer
    Plant and soil 154 (1993), S. 267-277 
    Details
    ISSN: 1573-5036
    Keywords: added nitrogen interactions ; groundnut ; maize ; nitrogen ; 15N-isotope methodology ; residual effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Four cultivars of groundnut were grown in upland soil in Northeast Thailand to study the residual benefit of the stover to a subsequent maize crop. An N-balance estimate of the total residual N in the maize supplied by the groundnut was made. In addition three independent estimates were made of the residual benefits to maize when the groundnut stover was returned to the land and incorporated. The first estimate (Estimate 1) was an N-balance estimate. A dual labelling approach was used where 15N-labelled stover was added to unlabelled microplots (Estimate 2) or unlabelled stover was added to 15N-labelled soil microplots (Estimate 3). The nodulating groundnut cultivars fixed between 59–64% of their nitrogen (as estimated by the 15N isotope dilution method using non-nodulating groundnut as a non-fixing reference) producing between 100 and 130 kg N ha-1 in their stover. Although the following maize crop suffered from drought stress, maize grain N and dry weights were up to 80% and 65% greater respectively in the plots where the stover was returned as compared with the plots where the stover was removed. These benefits were comparable with applications of 75 kg N ha-1 nitrogen in the form of urea. The total residual N estimates of the contribution of the nodulated groundnut to the maize ranged from 16.4–27.5 kg N ha-1. Estimates of the residual N supplied by the stover and fallen leaves ranged from 11.9–21.3 kg N ha-1 using the N-balance method (Estimate 1), from 6.3–9.6 kg N ha-1 with the labelled stover method (Estimate 2) and from 0–11.4 kg N ha-1 with the labelled soil method. There was closest agreement between the two 15N based estimates suggesting that ‘apparent added nitrogen interactions’ in these soils may not be important and that N balance estimates can overestimate the residual N in crops following legumes, even in very poor soils. This work also indicates the considerable ability of local groundnut cultivars to fix atmospheric nitrogen and the potential benefits from returning and incorporating legume residues to the soil in the upland cropping systems of Northeast Thailand. The applicability of the 15N methodology used here and possible reasons for the discrepancies between estimates 1, 2 and 3 are discussed.
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    URL: http://dx.doi.org/10.1007/BF00012532
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    Nitrogen use efficiency of rice reconsidered: What are the key constraints? (1993)
    Springer
    Plant and soil 155-156 (1993), S. 359-362 
    Details
    ISSN: 1573-5036
    Keywords: 15N ; microbial biomass ; nitrogen uptake efficiency ; Oryza sativa ; soil nitrogen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Recent field studies on irrigated rice at the IRRI research farm indicate efficient use of fertilizer-N based on plant uptake of applied N, (estimated by N difference), and utilization of acquired N for increased grain yield. These findings contrast with 15N uptake in microplot studies which underestimate the actual increase in plant N from added fertiliser. Constraints other than uptake efficiency, however, may govern fertiliser-N efficiency in farmers fields. In a study of 44 farmers' fields in Central Luzon, rice yields ranged from 2.5 to 6.2 t ha-1 and N uptake from 35 to 95 kg N ha-1 in plots without fertiliser-N addition. Farmers applied from 35 to 240 kg N ha-1, but there was no relationship between the N rate used by each farmer and the effective soil N supply. Mean N uptake efficiency from fertiliser by N difference was only 36%. We conclude that improved fertiliser-N efficiency by farmers will require a more information-intensive management strategy that makes N fertiliser inputs better fitted to the seasonal pattern of crop N demand and soil N supply.
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    URL: http://dx.doi.org/10.1007/BF00025057
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    Rice (Oryza sativa L.) germplasm suitable for direct sowing under flooded soil surface (1993)
    Springer
    Euphytica 67 (1993), S. 177-184 
    Details
    ISSN: 1573-5060
    Keywords: direct sowing ; flooded soil ; germplasm ; Oryza sativa ; rice ; seedling establishment ; seedling growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Screening for rice germplasm which can establish seedling from flooded soil was conducted using 256 accessions of conserved germplasm from the International Rice Germplasm Center (IRGC) and 404 accessions from the International Network for Genetic Evaluation for Rice (INGER), IRRI. IRGC germplasm represented broad genetic diversity while INGER germplasm involved desirable agronomic characters. Seeds germinated for 2 d were planted at 25 mm depth in seedling trays. The trays were then submerged to a depth of 30–50 mm. Seedling establishment was evaluated by analyzing leaf development, seedling height, and percentage establishment 15 d after planting. Eight percent and 2% of IRGC and INGER germplasm, respectively, were identified statistically as superior to the control semidwarf IR varieties. Among the superior germplasm were those from Northeast India and Bangladesh which were adapted to deepwater and early summer rainfed lowland cultures. These could be utilized as parents in breeding programs which aim to develop varieties suitable for direct seeding technology (i.e., germinated seeds are sown under the surface of flooded soil).
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    URL: http://dx.doi.org/10.1007/BF00040619
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    Pollen tube growth in crosses between Porteresia coarctata and Oryza sativa (1993)
    Springer
    Euphytica 69 (1993), S. 129-134 
    Details
    ISSN: 1573-5060
    Keywords: Porteresia coarctata ; Oryza sativa ; rice ; intergeneric cross ; fluorescent microscopy ; pollen tube ; callose ; postzygotic barrier
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Comparative study with fluorescence microscopy revealed that the pollen tubes of the self-pollinated rice variety BR-9 reached the ovary within 75 min after pollination. In P. coarctata it took 150 min. In the cross between P. coarctata and BR-9, pollen tubes reached the ovary in 165 min but seed setting was not observed. In the cross between BR-9 and P. coarctata, small and deformed pollen tubes were formed and they failed to grow through the stylodium.
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    URL: http://dx.doi.org/10.1007/BF00021736
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    Variation in resistance of Mexican landraces of maize to maize weevil Sitophilus zeamais, in relation to taxonomic and biochemical parameters (1993)
    Springer
    Euphytica 74 (1993), S. 227-236 
    Details
    ISSN: 1573-5060
    Keywords: resistance ; taxonomy ; maize ; maize weevil ; indigenous landraces ; phenolic acids ; life history components ; indirect selection ; Zea mays ; Sitophilus zeamais
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Accessions representing twenty eight landraces of maize were assessed for susceptibility to the maize weevil, Sitophilus zeamais in standardized resistance tests. Susceptibility parameters such as weight loss of grain, number of insect progeny produced, the Dobie index of susceptibility, and oviposition on grain were found to vary significantly by genotype, with exceptional resistance found in accessions representing the Naltel, Chapalote and Palomero landraces. As in improved genotypes, susceptibility was negatively correlated to phenolic and protein content of the variety tested but positively correlated to moisture content. A detailed analysis of the phenolics revealed the presence of diferulate which may contribute to mechanical resistance of the seed by cross-linking of cell wall hemicelluloses. A canonical discriminant analysis of the resistance data suggests that most of the five landrace groupings are significantly different. The ancient indigenous and prehistoric mestisos groupings are sources of resistant genotypes.
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    URL: http://dx.doi.org/10.1007/BF00040405
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    Indica-japonica differentiation in Chinese rice landraces (1993)
    Springer
    Euphytica 74 (1993), S. 195-201 
    Details
    ISSN: 1573-5060
    Keywords: Oryza sativa ; landraces ; varietal differentiation ; hsien and keng ; indica and japonica ; isozymes ; chloroplast DNA (cpDNA) ; Polymerase Chain Reaction (PCR)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Ninety Chinese rice landraces were examined with special reference to the indica-japonica differentiation in terms of traditional criteria, isozyme analysis and PCR analysis of the chloroplast DNA (cpDNA). Cultivars were separated into indica and japonica defined by a discriminant function (Z) based on key characters, as well as by isozyme genotypes. Most indica landraces had chloroplast DNAs with a deletion at the Pst-12 fragment, while most japonica landraces had cpDNAs without the deletion. Two traditionally recognized varietal groups in China, keng and hsien, corresponded largely to the respective japonica and indica revealed in our study. The results obtained in this study showed good agreement for classification of indica and japonica types by the three methods: discriminant analysis by Z value, isozyme analysis, and PCR analysis for cpDNA.
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    URL: http://dx.doi.org/10.1007/BF00040401
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    Siderophore-mediated competition for iron and induced resistance in the suppression of fusarium wilt of carnation by fluorescent Pseudomonas spp (1993)
    Springer
    European journal of plant pathology 99 (1993), S. 277-289 
    Details
    ISSN: 1573-8469
    Keywords: antibiosis ; biological control ; disease resistance ; Fusarium oxysporum f.sp.dianthi ; root colonization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The mechanisms of suppression of fusarium wilt of carnation by two fluorescentPseudomonas strains were studied. Treatments of carnation roots withPseudomonas sp. WCS417r significantly reduced fusarium wilt caused byFusarium oxysporum f. sp.dianthi (Fod). Mutants of WCS417r defective in siderophore biosynthesis (sid−) were less effective in disease suppression compared with their wild-type. Treatments of carnation roots withPseudomonas putida WCS358r tended to reduce fusarium wilt, whereas a sid− mutant of WCS358 did not. Inhibition of conidial germination of Fod in vitro by purified siderophores (pseudobactins) of bothPseudomonas strains was based on competition for iron. The ferrated pseudobactins inhibited germination significantly less than the unferrated pseudobactins. Inhibition of mycelial growth of Fod by bothPseudomonas strains on agar plates was also based on competition for iron: with increasing iron content of the medium, inhibition of Fod by thePseudomonas strains decreased. The sid− mutant of WCS358 did not inhibit Fod on agar plates, whereas the sid− mutants of WCS417r still did. This suggests that inhibition of Fod by WCS358r in vitro was only based on siderophore-mediated competition for iron, whereas also a non-siderophore antifungal factor was involved in the inhibition of Fod by strain WCS417r. The ability of thePseudomonas strains to induce resistance against Fod in carnation grown in soil was studied by spatially separating the bacteria (on the roots) and the pathogen (in the stem). Both WCS417r and its sid− mutant reduced disease incidence significantly in the moderately resistant carnation cultivar Pallas, WCS358r did not. It is concluded that the effective and consistent suppression of fusarium wilt of carnation by strain WCS417r involves multiple mechanisms: induced resistance, siderophore-mediated competition for iron and possibly antibiosis. The less effective suppression of fusarium wilt by WCS358r only depends on siderophore-mediated competition for iron.
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    Incidence and ecological relationships of pupal parasitism byBrachymeria intermedia in new Jersey populations of the gypsy moth (1993)
    Springer
    BioControl 38 (1993), S. 257-266 
    Details
    ISSN: 1573-8248
    Keywords: Lymantria dispar ; gypsy moth ; pupal parasitism ; density dependence ; biological control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé Le parasitisme nymphal deLymantria dispar a été étudié dans 15 placettes du New Jersey, de 1978 à 1988. Le principal parasitoïde était un chalcidien,Brachymeria intermedia (Nees), qui n'a été trouvé que dans 6 placettes. Le parasitisme s'observait généralement dans l'année même ou dans celle précédant l'apparition du maximum d'ooplaques deL. dispar. Un seul site montrait un taux de parasitisme dépassant 4%. Le pourcentage de parasitisme était significativement corrélé avec le nombre d'ooplaques par ha de la saison en cours et avec le nombre de nymphes par site de la saison précédente, suggérant une densité-dépendance retardée. Une analyse de régression multiple a révélé un pourcentage de parasitisme significativement corrélé avec le pourcentage d'infection par le virus de la polyhédrose nucléaire, la densité de nymphes hôtes mâles, les températures minimales moyennes en août et en mars. Une analyse canonique discriminante, effectuée pour différencier les sites avec ou sans parasitoïdes, a été significative. Les placettes avecB. intermedia présentent des populations d'hôtes et une défoliation relativement plus élevées.
    Notes: Abstract Pupal parasitism of the gypsy moth,Lymantria dispar (L.), was monitored in 15 study plots in New Jersey from 1978 to 1988. The predominant parasitoid was a chalcidid wasp,Brachymeria intermedia (Nees), which was found in only six plots. Parasitism was generally observed in the year of or preceding the peak numbers of gypsy moth egg masses. Parasitism exceeded 4% in only one plot. Percentage parasitism was correlated significantly with numbers of egg masses per hectare in the current season and with numbers of pupae per plot in the previous season, suggesting delayed density dependence. A multiple regression analysis found percentage parasitism to be correlated significantly with percentage infection by nuclear polyhedrosis virus, density of male host pupae, and mean minimum temperature in August and March. A canonical discriminant analysis carried out to distinguish study plots with and without the parasitoid was significant. Plots withB. intermedia had relatively higher host populations and defoliation.
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    The use of sexual versus asexual wasps in biological control (1993)
    Springer
    BioControl 38 (1993), S. 3-6 
    Details
    ISSN: 1573-8248
    Keywords: biological control ; thelytoky ; arrhenotoky ; sexual reproduction ; asexual reproduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02373133
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    Life histories ofPsyllaephagus yaseeni (Hym., Encyrtidae) andTamarixia leucaenae (Hym., Eulophidae), parasitoids of the leucaena psyllidHeteropsylla cubana (1993)
    Springer
    BioControl 38 (1993), S. 565-577 
    Details
    ISSN: 1573-8248
    Keywords: Psyllaephagus ; Tamarixia ; Heteropsylla ; biological control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé La fécondité en fonction de l'âge de deux parasitoïdes du psylleHeteropsylla cubana, Psyllaephagus yaseeni etTamarixia leucaenae a été étudiée en condition de laboratoire. A 25 °C,P. yaseeni présente une fécondité plus élevée (R0=192,9) queT. leucaenae (R0=71,2);T. leucaenae montre cependant une sex ratio plus faible (environ 99 % de femelles) queP. yaseeni (environ 50 %). Le taux d'accroissement potentiel (rm=0,236) deT. leucaenae était plus élevé que celui deP. yaseeni (rm=0,188). Les vitesses de développement des parasitoïdes ont été examinées à des températures constantes et fluctuantes et les équations de la vitesse de développement en fonction de la température ont été calculées. A 25 °C, la durée moyenne des générations était respectivement de 28,0 et 18,1 jours pourP. yaseeni etT. leucaenae. Aux températures de 21,5, 25 et 30 °C la durée totale de développement (de l'œuf à l'adulte) était de 28,5, 21,9 et 14,7 jours chezP. yaseeni et 19,2, 12,6 et 9,5 jours chezT. leucaenae. Le taux de parasitisme était faible et la mortalité nymphale était élevée à la température la plus basse, 21,5 °C, pour les deux parasitoïdes. Tous deux présentaient une survie faible à 100 % de HR;P. yaseeni survivait particulièrement bien à une température de 21 °C et à 44 ou 76% d'HR. P. yaseeni attribuait environ 58 % de femelles aux larves de premier stade de développement mais seulement 12 % aux larves de second stade. Environ 99 % de toutes les éclosions deT. leucaenae était constituée de femelles. La taille des femelles issues des larves de 5e stade étaient significativement supérieure à la taille de celles qui émergeaient des larves de 3e ou 4e stade.
    Notes: Abstract Age specific fecundity of two parasitoids,P. yaseeni andT. leucaenae, of the leucaena psyllidH. cubana, were studied under laboratory conditions. At 25 °C,P. yaseeni had a greater fecundity (R0=192.9)_thanT. leucaenae (R0=71.2);T. leucaenae however had a lower sex ratio (about 99 % females) thanP. yaseeni (about 50 % females). Innate capacity for increase (rm=0.236) ofT. leucaenae was higher thanP. yaseeni (rm=0.188). Developmental rates of the parasitoids were examined at constant and fluctuating temperatures and equations of the rate of development against temperature were calculated. At 25 °C, mean generation times were 28.0 and 18.1 days forP. yaeseeni andT. leucaenae respectively. At temperatures of 21.5, 25, and 30 °C total development times (egg to adult) were 28.5, 21.9, and 14.7 days inP. yaseeni and 19.2, 12.6, and 9.5 days inT. leucaenae respectively. The level of parasitism was low and pupal mortality was high at the lower temperature of 21.5 °C for both parasitoids. Both parasitoids showed poor survivorship at 100 % RH,P. yaseeni survived particularly well (32 days) at a temperature of 21.5 °C and 44 or 76 % RH. P. yaseeni allocated about 58 % females to first instar psyllid nymphs but only 12 % females to second instars. About 99 % of allT. leucaenae births were females. Significantly largerT. leucaenae females emerged from fifth instar parasitized nymphs than third or fourth instars.
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    Effects of high temperature shocks on the development and biology ofTrichogramma brassicae [Hym.: Trichogrammatidae] (1993)
    Springer
    BioControl 38 (1993), S. 185-192 
    Details
    ISSN: 1573-8248
    Keywords: parasitoid ; biological control ; heat shock
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé Suite à une efficacité parasitaire faible des trichogrammes, constatée, dans des conditions climatiques particulières lors des lâchers de ces parasitoïdes contre la pyrale du maïs, des chocs thermiques à 35°C et 44°C pendant une durée de 6 heures sont appliqués au stade nymphal deTrichogramma brassicae Bezdenko. Deux âges sont choisis: nymphe blanche et nymphe mélanisée. Différents critères biologiques ont été étudiés pour la génération G0 ayant subi le choc de température et pour les descendants G1. Les résultats obtenus indiquent une sensibilité des deux âges, surtout à 44°C. Cette température provoque une réduction du pouvoir parasitaire de la G0 de 51% pour les individus issus des nymphes blanches traitées et de 55% pour ceux issus des nymphes mélanisées traitées. Au niveau de la génération G1, on constate une chute de la proportion des femelles dans la descendance des adultes issus des deux âges traités: réduction de 38% pour les individus issus des nymphes mélanisées; 88% pour ceux issus des nymphes blanches. Dans ce dernier cas, la génération G1 pratiquement totalement mâle, est obligatoirement sans efficacité parasitaire.
    Notes: Abstract Trichogramma brassicae Bezdenko is used throughout Europe as an effective biological control agent against the European corn borer (Ostrinia nubilalis Hübner). However, in certain climatic regions, the biological control exerted by this parasitoid is less effective. High temperatures inside the released capsules are suspected to have a negative influence on the parasitoids. To simulate these adverse conditions, we applied heat shocks (35°C and 44°C) for 6 hours to pupae ofTrichogramma brassicae at two periods: white pupae and melanized pupae. The results showed the susceptibility of both the white pupae and melanized pupae, especially at 44°C. At this temperature, the adults (G0 generation) derived from pupae treated at any age showed reduced longevity and fecundity. Moreover, those descended from treated melanized pupae showed an emergence rate lower than that of the control. These effects reduced to half and more the parasitic efficiency of the G0 generation. For the progeny (G1 generation), we observed a decrease of the female ratio: 38% for the progeny of adults derived from treated melanized pupae; 88% for the progeny of those derived from treated white pupae. In that condition, the G1 generation, almost totally male, could not have any parasitic activity.
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    The potential of carabid beetles to control slugs in grass/clover swards (1993)
    Springer
    BioControl 38 (1993), S. 193-198 
    Details
    ISSN: 1573-8248
    Keywords: biological control ; predation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé Des expériences menées en conditions contrôlées dans des boîtes carrées semées de trèfle ou de ray grass ont montré que les CarabesAbax parallelepipedus (Piller & Mitterpacher) etPterostichus madidus F. limitent les populations de limaces dans les champs de trèfle et de ray grass. La limitation par ces carabes se révèle aussi bonne que celle obtenue avec le molluscicide methiocarb.A. parallelepipedus semble plus efficace queP. madidus dans ce rôle, les dégâts sur le trèfle étant maintenus à un minimum.P. madidus ne limite les limaces qu'une fois le trèfle déjà attaqué.
    Notes: Abstract Experiments conducted in sward boxes under controlled conditions showed that the carabid beetlesAbax parallelepipedus (Piller & Mitterpacher) andPterostichus madidus F. controlled slugs in a grass/clover sward. Control was shown to be as good as that by the molluscicide, methiocarb.A. parallelepipedus proved to be more successful thanP. madidus at controlling the slugs, damage to the clover being kept to a minimum.P. madidus controlled the slugs only after some damage to the clover was sustained.
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    Host-size preference of the parasitoidAnisopteromalus calandrae [Hym: Pteromalidae] onSitophilus zeamais (Col.: Curculionidae) larvae with a uniform age distribution (1993)
    Springer
    BioControl 38 (1993), S. 225-233 
    Details
    ISSN: 1573-8248
    Keywords: host size preference ; parasitoid ; stored product ; maize ; biological control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé La première génération d'Anisopteromalus calandrae (Howard) récoltée dans du maïs stocké commercialement en Caroline du Sud fut exposée, dans du maïs écossé, à un mélange de jeunesSitophilus zeamais Motschulsky, de toutes tailles représentant une distribution d'âge uniforme. On a observé 87% de parasitisme sur les larves comportant un tunnel de 0,9 à 1,8 mm et 6% sur les prépupes et pupes pour cette distribution d'âge. Le taux de préférence était le plus élevé pour les grosses larves-hôte (1,6 mm de diamètre), moyen pour les autres larves de 0,9 à 1,8 mm, et le plus bas pour les pupes et les petites larves. On a discuté de la sélectivité des hôtes en utilisant les paramètres de Chesson (1983): préférence, αi, probabilité de parasitisme, Pi, et index d'électivité ɛi.
    Notes: Abstract First generationAnisopteromalus calandrae (Howard) collected from commercial stored maize in South Carolina were exposed to a mixture of all sizes of immatureSitophilus zeamais Motschulsky, representative of a uniform age distribution, in shelled maize. Eighty-seven percent of parasitism is expected on larvae with tunnel diameters of 0.9 to 1.8 mm and 6% on prepupae and pupae, given this host-size distribution. Preference was greatest for large host larvae (1.6 mm diameter), intermediate for other larvae in the range 0.9 to 1.8 mm, and least for pupae and small larvae. Host-stage preference is discussed with respect to Chesson's (1983) parameters for preference, αi, probability of parasitism, Pi, and electivity index, ɛi.
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    Survey of the parasitoids of the tuliptree aphid,Illinoia liriodendri (Hom: Aphididae), in northern California (1993)
    Springer
    BioControl 38 (1993), S. 31-40 
    Details
    ISSN: 1573-8248
    Keywords: Aphidius polygonaphis ; Illinoia liriodendri ; Liriodendron tulipifera ; tuliptree aphid ; biological control ; hyperparasitoids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé Un recensement du cortège parasitaire deIllinoia liriodendri (Monell) effectué en Californie du nord de 1988 à 1990 a révélé la présence de 12 espèces de parasitoïdes primaires et de 14 espèces d'hyperparasitoïdes. Le plus abondant des parasitoïdes primaires,Aphidius polygonaphis (Fitch), importé dans les années 1970, est à présent établi dans toute la région. Sont signalés pour la première fois associés àI. liriodendri les parasitoïdes primaires suivants:A. ervi Haliday,A. avenaphis (Fitch),Praon occidentale Baker,P. unicum Smith,Diaeretiella rapae M'Intosh,Lysiphlebus testaceipes (Cresson), etMonoctonus nervosus (Haliday) [tous Hymenoptera: Braconidae: Aphidiinae] etAphelinus sp. nr.asychis Walker [Hymenoptera: Aphelinidae]. Les hyperparasitoïdes les plus abondants sontPachyneuron aphidis (Bouché) etAsaphes californicus Girault [tous deux Hymenoptera: Pteromalidae]Pachyneuron californicum Girault etCoruna clavata Walker [Hymenoptera: Pteromalidae] sont signalés pour la première fois comme hyperparasitoïdes sur Aphidiinae et Aphelinidae spp. pour le premier, et surAphelinus sp. pour le second.
    Notes: Abstract A survey of the parasitoids ofIllinoia liriodendri (Monell) in northern California conducted from 1988–1990 revealed the presence of 12 primary and 14 hyper-parasitoid species. The most common primary parasitoid wasAphidius polygonaphis (Fitch), which was imported from the eastern United States in the 1970's and is now established throughout the area. New host records were noted forA. ervi Haliday,A. avenaphis (Fitch), Praon occidentale Baker,P. unicum Smith,Diaeretiella rapae M'Intosh,Lysiphlebus testaceipes (Cresson), andMonoctonus nervosus (Haliday) (all Hymenoptera: Braconidae: Aphidiinae), andAphelinus sp. nr.asychis Walker (Hymenoptera: Aphelinidae). The most common hyperparasitoid species werePachyneuron aphidis (Bouché) andAsaphes californicus Girault (both Hymenoptera: Pteromalidae). New hyperparasitoid host records were noted forPachyneuron californicum Girault on Aphidiine and Aphelinidae spp. andCoruna clavata Walker (Hymenoptera: Pteromalidae) onAphelinus sp.
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    Dryinid (Hym.: Dryinidae) parasitoids ofDalbulus leafhopper (Hom.: Cicadellidae) in Mexico (1993)
    Springer
    BioControl 38 (1993), S. 41-49 
    Details
    ISSN: 1573-8248
    Keywords: Insect parasitoids ; Dryinidae ; Dalbulus ; maize ; teosintes ; Tripsacum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé Les connaissances relatives aux ennemis naturels des Cicadelles du genre Dalbulus [Hom.: Cicadellidae] sont encore limitées. Dans l'état du Jalisco, au Mexique, a été réalisée une étude sur les dryinides (petites guêpes), parasitoïdes de ces cicadelles. L'état du Jalisco abrite le plus grand nombre d'espèces deDalbulus et se trouve localisé dans la région d'origine deDalbulus ainsi que de ses plantes hôtes: maïs, téosinte (Zea) etTripsacum. Le dryinideGonatopus bartletti a été rencontré parasitantDalbulus maidis sur des plantes de maïs ainsi que sur le téosinte annuelZea mays spp.parviglumis: G. flavipes a été identifié parasitantD. elimatus sur le téosinte pérenne,Zea perennis; de plus, une nouvelle espèce,G. moyaraygozai, ainsi queAnteon ciudadi ont été observés en tant que parasites deD. quinquenotatus surTripsacum pilosum et surTripsacum dactyloides. Le parasitisme par des dryinides a été observé à des altitudes comprises entre 680 et 2 000 m s.n.m..Dalbulus maidis, espèce qui cause les pertes de rendement les plus importantes en Amérique latine, est parasité entre 680 m s.n.m. et 1 760 m s.n.m.. Les espèces deDalbulus associées à des plantes hôtes annuelles (maïs etZ. mays spp.parviglumis) ont été parasitées par des dryinides pendant la saison des pluies alors que les espèces deDalbulus associées à des plantes hôtes pérennes (Z. perennis etTripsacum) ont été parasitées par des dryinides pendant la saison des pluies et la saison sèche. La plus grande diversité d'espèces parasitantDalbulus spp. ainsi que la plus grande fréquence de parasitisme ont été rencontrées sur ces espèces pérennes, suggérant que ces plantes sont des réservoirs d'ennemis naturels deDalbulus spp.
    Notes: Abstract Little is known about the natural enemies of the leafhopperDalbulus spp. (Homoptera: Cicadellidae). Searches for its dryinid (wasps) parasitoids were made in Jalisco, Mexico. Jalisco contains the greatest number ofDalbulus species, and is considered to be near to the center of origin of this leafhopper genus and its host plants: maize, teosintes (Zea spp.) and gamagrasses (Tripsacum spp.). The dryinidGonatopus bartletti was found parasitizingD. maidis on maize and on annual teosinteZea mays spp.parviglumis. G. flavipes was found parasitizingD. elimatus on perennial teosinteZ. perennis; and a new speciesG. moyaraygozai andAnteon ciudadi parasitizingD. quinquenotatus onTripsacum pilosum andT. dactyloides. Parasitism by dryinids was found at altitudes of 680–2,000 m.Dalbulus maidis, the leafhopper species which causes the greatest losses in maize in Latin America, was found to be parasitized from 680–1,760 m. TheDalbulus species associated with annual host plants (maize andZ. mays spp.parviglumis) were parasitized by dryinids during the rainy season, while theDalbulus species associated with perennial host plants (Z. perennis andTripsacum) were parasitized by dryinids during both the rainy and dry season. The greatest diversity of dryinid parasitoids ofDalbulus spp. and the highest levels of parasitism were recorded from perennial plants, indicating that such species are reservoirs of natural enemies ofDalbulus spp.
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    First observations in glasshouse sweet peppers in Belgium and laboratory rearing of the parasitic waspEulophus pennicornis (Hym.: Eulophidae) (1993)
    Springer
    BioControl 38 (1993), S. 61-62 
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    ISSN: 1573-8248
    Keywords: Mamestra brassicae ; Chrysodeixis chalcites ; parasitoid ; sweet pepper ; biological control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Eulophus pennicornis, a hymenopteran parasitoid of several Lepidoptera, was found onMamestra brassicae in a commercial sweet pepper crop in 1990 in Belgium. The rearing of the parasitoid and some additional data on biology are described.
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    Biological control of the mediterranean black scale,Saissetia oleae (Hom.: Coccidae) in Israel (1993)
    Springer
    BioControl 38 (1993), S. 89-100 
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    ISSN: 1573-8248
    Keywords: parasitoid ; biological control ; release of beneficial arthropods
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé Entre 1975 et 1982, l'Institut de Lutte biologique “Israël Cohen” a mis en place un programme de lutte biologique contre la cochenille noire de l'olivierSaissetia oleae (Olivier) (Hom.: Coccidae). Au cours de cette période, 17 espèces d'ennemis naturels furent introduites en Israël, et les populations du ravageur retombèrent à un niveau acceptable. Le principal parasitoïde responsable de cette réduction a étéMetaphycus bartletii A. & M. (Hym.: Encyrtidae). Cet article expose le programme et apporte en outre quelques données sur la biologie des parasitoïdes introduits.
    Notes: Abstract During the years 1975–1982, the “Israel Cohen” Inst. for Biological Control conducted a biological control project, against the black scale,Saissetia oleae (Olivier) (Homoptera: Coccidae). Seventeen species of natural enemies were introduced into Israel during that period, and their action reduced the populations of the pest to an acceptable level. The major parasitoid responsible for that transition wasMetaphycus bartletti Annecke & Mynhardt (Hymenoptera: Encyrtidae). This article describes the project and introduces some notes on the biology of the introduced parasitoids.
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    IndigenousTrichogramma (Hym.: Trichogrammatidae) parasitizing eggs ofRhopobota naevana (Lep.: Tortricidae) on cranberries in British Columbia (1993)
    Springer
    BioControl 38 (1993), S. 313-315 
    Details
    ISSN: 1573-8248
    Keywords: biological control ; parasitism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Two indigenous species ofTrichogramma were reared from natural populations of the blackheaded fireworm,Rhopobota naevana (Hübner) infesting cranberries in British Columbia, Canada. One was identified asTrichogramma sp. nr.sibericum Sorokina and the other wasTrichogramma minutum Riley. Percentage of parasitized hosts increased during the season in an abandoned field, but decreased in a commercial field where pesticides were used. The potential ofTrichogramma as a biological control agent against the fireworm is discussed.
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    Successful colonization ofEretmocerus debachi (Hym.: Aphelinidae) in the eastern mediterranean citrus region of Turkey (1993)
    Springer
    BioControl 38 (1993), S. 383-390 
    Details
    ISSN: 1573-8248
    Keywords: biological control ; Parabemisia myricae ; Eretmocerus debachi ; Citrus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé L'aleurodeParabemisia myricae (Kuwana) est l'un des plus sérieux ravageurs des vergers de citrus dans la région métiterranéenne de l'est de la Turquie. En 1986, un parasitoïde spécifique deP. myricae, l'aphelinideEretmocerus debachi Rose et Rosen, était introduit de Californie en Turquie et lâché dans les vergers de Citrus le long de la côte méditerranéenne orientale. Au cours des années suivantes, les populations deP. myricae étaient rapidement tombées d'environ 17 aleurodes au stade immature par feuille à moins de 0,1 par feuille dans tous les vergers de citrus où les parasitoïdes ont été lâchés. De plus,E. debachi a montré une bonne capacité de dispersion et s'est bien adapté aux conditions climatiques de la région orientale. Depuis l'installation réussie deE. debachi, l'aleurode n'est plus un ravageur dangereux et il est difficile de trouver des individus non parasités dans la région méditerranéenne de l'est de la Turquie.
    Notes: Abstract The whitefly,Parabemisia myricae (Kuwana) is one of the most serious citrus pests in the Eastern Mediterranean region of Turkey. In 1986, a host-specific parasitoid ofP. myricae, the aphelinidEretmocerus debachi Rose and Rosen, was imported from California to Turkey and released into citrus orchards along the Eastern Mediterranean coast. In the following yearsP. myricae-populations were rapidly reduced from about 17 whitefly-immature stages per leaf to less than 0.1 stages per leaf in all citrus orchards where the parasitoids were released. Furthermore,E. debachi was shown to be a good disperser and it is well adapted to the climatic conditions in the Eastern Mediterranean region. Since the successful colonization ofE. debachi, the whitefly is no longer a serious pest and it is difficult to find unparasitized individuals in the Eastern Mediterranean region of Turkey.
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    Sex ratios in natural populations ofAphelinus mali (Hym.: Aphelinidae) in relation to host size and host density (1993)
    Springer
    BioControl 38 (1993), S. 391-403 
    Details
    ISSN: 1573-8248
    Keywords: sex ratio ; parasitoid ; biological control ; Australia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé Dans un verger de pommier à Armidale, sur les plateaux du nord de la Nouvelle Galles du Sud la sex ratio des populations d'Aphelinus mali, un endoparasitoïde d'Eriosoma lanigerum varie de 0,51 (pourcentage de mâles) pour de faibles densités de l'hôte à des proportions favorables aux femelles pour des densités d'hôtes élevées (pourcentage de mâles compris entre 0,35 et 0,39). Cette variation dans la sex ratio est apparemment due à des différences dans l'attribution d'une descendance mâle ou femelle en fonction de la taille de l'hôte. dans la nature,A. mali parasite le puceron du pommier à tous les stades de son développement (les 4 stades larvaires et l'adulte). D'après le modèle du régime optimal de Hughes (1979), l'acceptation de l'hôte sous toutes ses formes semble être la meilleure stratégie. Cependant, il permet à l'hôte de continuer son développement (dans le cas d'un stade larvaire) ou de se reproduire (au stade adulte) jusqu'à la momification. Aucune mortalité n'est observée en laboratoire lorsque l'hôte est parasité au 1° ou au 2° stade larvaire. Des momies de petite taille récoltées sur le terrain présentent une sex ratio favorable aux mâles alors que des momies de grande taille produisent surtout des femelles. En laboratoire, la descendance issue des hôtes de faible taille (du 1° au 3° stade) présente une sex ratio qui n'est pas significativement différente de 0,5 alors que la descendance issue des hôtes de grande taille (3° et 4° stade) montre une sex ratio favorable aux femelles. Pendant l'hiver (juin–août) et le début du printemps (septembre–octobre), c'est-à-dire à la période où la population hôte dans le verger est constituée principalement de larves, le parasitoïde tend à produire autant de mâles que de femelles. En revanche, aux pics de densité de population, en été et en automne (décembre à mai) lorsque des hôtes de grande taille sont disponibles, la sex ratio est favorable aux femelles. La taille de l'hôte,E. lanigerum et celle deA. mali, sont donc des éléments importants pour la dynamique des relations hôtes-parasitoïdes.
    Notes: Abstract In an apple orchard at Armidale, the Northern Tablelands of NSW, population sex ratios ofAphelinus mali (Haldeman), an endoparasitoid of the woolly apple aphid,Eriosoma lanigerum (Hausmann) varied from 0.51 (proportion of males) at low host densities to female-biased at high host densities (proportion of males ranged from 0.35–0.39). This shift in sex ratio seems to be caused by the differences in allocation of sons and daughters to hosts of different sizes. In the fieldA. mali parasitizes all life stages (four nymphal instars and adult) of the woolly aphid upon encountering. According to Hughes'(1979) optimal diet model, such general host acceptance seems to be the best strategy. However, it allows the host nymphs or adults to continue to develop or reproduce until about to mummify (pupate). No mortality was observed when first or second-instar hosts were parasitized in the laboratory. Field collected small mummified hosts yielded male-biased sex ratios whereas large mummified hosts produced mainly females. In the laboratory, progeny from smaller hosts (first to third-instars) produced sex ratios which were not significantly different from 0.5 whereas progeny from larger hosts (third and fourth-instars) produced female-biased sex ratio. During winter (June–August) and early spring (September–October) when the host populations in the orchard were predominantly nymphs, the parasitoid tended to allocate equal resources to male and female offspring. In contrast, at peak population densities in summer and autumn (December–May) when larger hosts were available, the sex ratios were female-biased. The host size ofE. lanigerum andA. mali is, therefore, an important component in the dynamics of host-parasitoid interactions.
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    Host range ofPachycerus cordiger (=P. Scabrosus) (Col.: Curculionidae) (1993)
    Springer
    BioControl 38 (1993), S. 537-539 
    Details
    ISSN: 1573-8248
    Keywords: Life cycle ; host specificity ; Pachycerus cordiger ; Heliotropium europaeum ; Boraginaceae ; biological control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The univoltine weevilPachycerus cordiger Germar (=P. scabrosus Brullé) completes its life cycle on species of Boraginaceae, it is found from western Europe to the Middle East. In southern France, adultP. cordiger were collected feeding on the leaves ofHeliotropium europaeum L.,Echium vulgare L. andCynoglossum creticum Miller, whereas larvae were found feeding externally on the roots of the three plant species from within an earthen cell. BecauseP. cordiger is considered too much of a generalist to be released in Australia, work on the weevil as a potential biological control agent ofH. europaeum has been stopped.
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    Biological studies ofDiadegma semiclausum (Hym., Ichneumonidae), a parasite of diamondback moth (1993)
    Springer
    BioControl 38 (1993), S. 579-586 
    Details
    ISSN: 1573-8248
    Keywords: Plutella xylostella ; Diadegma semiclausum ; biological control ; biology ; temperature effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé Des études en laboratoires ont été menées sur certains aspects de la biologie deDiadegma semiclausum Hellén, parasitoïde larvaire d'un ravageur des crucifères,Plutella xylostella (L.). Entre 15 et 35°C, plus la température est élevée, plus courte est la durée du développement des stades larvaires et adulte. L'éclosion et l'émergence des adultes est élevée entre 15 et 30°C mais elle est significativement réduite à 35°C. Plus la température est haute, plus la proportion de mâles est grande. Le seuil théorique de développement est de 5,74°C pour les œufs; 3,80°C pour les larves, 5,91°C pour les nymphes et 6,60°C pour les adultes. La ponte deD. semiclausum dans les larves des trois premiers stades deP. xylostella produit plus de parasitoïdes mâles que de femelles mais la ponte dans le 4e stade produit significativement plus de femelles que de mâles. Les parasites adultes ont tendance à émerger de la nymphe entre 6 h et 9 h bien que quelques individus sortent à d'autres moments de la photophase. La longévité des adultes et la production d'œufs augmentent quand on fournit aux adultes de la nourriture (miel) par rapport à l'absence de nourriture ou la fourniture d'eau seule. Des parasites adultes survivent et pondent pendant 28 jours lorsqu'on les nourrit mais seulement pendant 3 jours lorsqu'ils sont privés de nourriture.
    Notes: Abstract Laboratory studies were conducted on certain aspects of biology ofDiadegma semiclausum Hellén, a larval parasite of a crucifer pest,Plutella xylostella (L.). Within the range of 15°C to 35°C, the higher temperature, the shorter was the duration of larval and adult stages. Egg hatching and adult emergence were high at 15°C to 30°C but were significantly reduced at 35°C. The higher the temperature, the higher was the proportion of males produced. Temperature threshold was 5.74°C for eggs, 3.80°C for larvae, 5.91°C for pupae and 6.60°C for adults.D. semiclausum oviposition in the first threeP. xylostella larval instars produced more parasite males than females but oviposition in the fourth instar produced significantly more females than males. Parasite adults tended to emerge from their pupae from 06∶00 to 09∶00 hours although some emerged at other hours during the photophase. Adult longevity and production of eggs increased when adults were provided with a food source (honey) compared with no food or provision of water alone. Parasite adults survived and laid eggs for 28 days when provided with food but for only three days when deprived of food.
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    Effect of Leucaena leucocephala (Lam) de Wit. as a green manure on nitrogen uptake and yield of rice (1990)
    Springer
    Biology and fertility of soils 9 (1990), S. 68-70 
    Details
    ISSN: 1432-0789
    Keywords: Leucaena leucocephala ; Green manure ; N Uptake ; Yield ; Wetland rice ; Oryza sativa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Field studies were conducted over two seasons to examine the effect of Leucaena leucocephala as a green manure on the N uptake and yield of rice grown under lowland conditions. The treatments were 0, 4, 8, and 12t Leucaena ha-1 with 0,44, and 88 kg N ha-1 as urea in a factorial combination. N uptake was evaluated at maximum tillering, panicle initiation, and harvest. The incorporation of Leucaena increased N uptake throughout the vegetative period in both seasons, irrespective of the mineral-N level. At all levels of N, the grain yield increased significantly following the incorporation of Leucaena, and in both seasons the Leucaena treatment of 8 t ha-1 was almost as effective as the highest mineral-N application.
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    Response of early maturing maize (Zea mays, L) variety to potassium and zinc fertilization in the Nigerian savanna (1990)
    Springer
    Nutrient cycling in agroecosystems 23 (1990), S. 73-80 
    Details
    ISSN: 1573-0867
    Keywords: Nigerian savanna ; maize ; potassium ; zinc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A three year field study was conducted at five locations in the Nigerian savanna to evaluate the response of early maturing maize variety to varying rates of K and Zn with a view to establishing the K and Zn requirements for maize production in this zone. Treatments consisted of 4 × 3 factorial combinations of 4 levels of K and 3 levels of Zn. Responses to K and Zn fertilization were sporadic and were obtained only in soils of the Southern Guinea savanna and in the soil formed on sedimentary sandstone. There seem to be no problem at present in soils of the Northern Guinea and Sudan savannas where leaching is less intense. It is inferred from this study that K and Zn deficiences are incipient in the high rainfall soils and in the sandstone derived soils. For these soils, 50 kg K/ha and 2–5 kg Zn/ha is suggested as adequate for an early maturing maize crop. Soil data showed that K and Zn responses can be expected when available K and Zn levels fall below 0.1 meq/100 g and 2 ppm respectively.
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    Residual effect of long-term applications of farmyard manure to silage maize (1990)
    Springer
    Nutrient cycling in agroecosystems 26 (1990), S. 249-252 
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    ISSN: 1573-0867
    Keywords: Long-term manure trial ; residual effect ; model test ; nitrogen availability ; maize ; Italian ryegrass
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Sluijsmans and Kolenbrander developed a simple model to describe the availability of animal manure, assuming a readily available, an easily decomposable and a slowly decomposable N fraction. We tested this model on data from an experiment in which farmyard manure had been applied for eleven successive years to silage maize [Zea mays L.] grown on a light sandy soil. The residual effects of this FYM were then measured by growing Italian ryegrass [Lolium multiflorum Lamk.] in the 12th year. The measured uptake of N by the grass of the FYM residues was then compared with the computed values. The measured amounts of N taken up agreed fairly well with the calculated amounts for applications of 50 and 100 t FYM per ha per year. If the rates of manure application are adjusted to crop requirement, the model shows that the potential, long-term release of N from the residual N fraction of FYM will not exceed 20 kg N per ha. For cattle slurry with a smaller residual fraction, the release will be at most 10% of the total annual N application.
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    URL: http://dx.doi.org/10.1007/BF01048763
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    Potato tuber sugar content during development and storage (10°C): possible predictors of storage potential and the role of sucrose in storage hexose accumulation (1990)
    Springer
    Potato research 33 (1990), S. 241-245 
    Details
    ISSN: 1871-4528
    Keywords: reducing sugars ; processing quality ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Reducing sugar and sucrose contents of potato tubers (Solanum tuberosum L.) from six cultivars were monitored both during the growing season and after a four months storage period at 10°C. Significant correlations were found between tuber sugar contents (sucrose, reducing and total) measured at harvest and the reducing sugar content after storage. Similarly, in five of the six cultivars, the sucrose loss and the corresponding reducing sugar gain during storage were significantly correlated.
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    URL: http://dx.doi.org/10.1007/BF02358452
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    Interrelationships of the number of initial sprouts, stems, stolons and tubers per potato plant (1990)
    Springer
    Potato research 33 (1990), S. 269-274 
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    ISSN: 1871-4528
    Keywords: cultivar differences ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The relationships between the number of initial sprouts, the number of main stems, stolons and tubers per plant are depicted in 4-quadrant figures. The number of sprouts per seed tuber varied because of different pre-sprouting conditions and/or because of the use of different cultivars. Good linear relationships are shown between the numbers of sprouts and stems, stolons and tubers, and sprouts and tubers, but especially between stolons and tubers within each trial with the one cultivar. When comparing different experiments with the one cultivar the linear relationship between the numbers of stems and stolons disappeared. When comparing different cultivars, no relation was found between the numbers of sprouts and stems. These two cases also led to a statistically less significant relation between the number of sprouts planted and the number of tubers harvested.
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    URL: http://dx.doi.org/10.1007/BF02358456
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    The effect of temperature on the development of wilting and on progeny tuber infection of potatoes inoculated with South African strains of biovar 2 and 3 ofPseudomonas solanacearum (1990)
    Springer
    Potato research 33 (1990), S. 287-290 
    Details
    ISSN: 1871-4528
    Keywords: bacterial wilt ; controlled environment ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Potato plants, after inoculation with a South African strain of biovar 2 or a strain of biovar 3 ofPseudomonas solanacearum were grown in growth chambers at temperatures ranging from 14/16°C (dark/light) up to 25/30°C. When grown at 14/16°C or higher, plants inoculated with the biovar 2 strain developed wilting symptoms and internal symptoms on progeny tubers and the disease was transmitted by the progeny tubers. When the plants were inoculated with the biovar 3 strain, wilting symptoms developed from 18/20°C, internal symptoms on progeny tubers from 20/22°C and the disease was transmitted by progeny tubers from plants grown at 16/18°C or higher.
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    URL: http://dx.doi.org/10.1007/BF02358459
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    Compatibility of potatoes to contrasting seasonal conditions, to high temperatures and to water deficit: The association with time of maturation and yield potential (1990)
    Springer
    Potato research 33 (1990), S. 325-334 
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    ISSN: 1871-4528
    Keywords: Mediterranean region ; spring ; autumn ; cultivar response ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Genotypic variation in the adaptation of potatoes of several maturity classes to the specific climatological conditions of the autumn season, to the high summer temperatures and to water deficit, was studied. Late-maturing cultivars exhibited the highest yielding potential both in the spring and autumn seasons but specific compatibility of cultivars to the autumn was detected. The late-maturing cultivars were more susceptible to high temperatures than were the early ones. However, there were significant differences in susceptibility to high temperatures among cultivars of the same maturity class. Susceptibility to water deficit was similar in the various maturity classes, but there were differences in the susceptibility to drought among cultivars of the same maturity class. High yielding potential generally resulted also in acceptable tuber yields under conditions of water deficit. High temperatures in combination with a water deficit aggravated yield losses, especially in the late-maturing cultivars.
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    URL: http://dx.doi.org/10.1007/BF02359306
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    Potato cuttings as models to study maturation and senescence (1990)
    Springer
    Potato research 33 (1990), S. 97-108 
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    ISSN: 1871-4528
    Keywords: Solanum tuberosum L. ; photoperiod ; sucrose ; glucose ; fructose ; reducing sugars ; periderm ; crisp color ; chip color
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Single leaf cuttings with their subtended axillary buds proved to be useful models to study maturation and senescence in potato (Solanum tuberosum L.). Senescence was more rapid if the cultivar was early maturing or if plants were exposed to short days before cuttings were taken. Rooting was decreased by short days before cutting; excision of the buried bud only partially overcame the effects on senescence and rooting. High rates of N to mother plants in the field delayed senescence of cuttings in a way analogous to the delayed senescence of field plants. The tuberization of cuttings from late maturing cultivars was decreased by high rates of N. The color of crisps made from bud tubers was positively correlated with the color of crisps made from ordinary tubers of the same cultivars. Sugar concentrations in bud tubers decreased as cuttings became more senescent and increased after cold storage. Bud tubers harvested while ‘immature’ had greater concentrations of reducing sugars after 90 d at 10°C than did ‘mature’ bud tubers.
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    URL: http://dx.doi.org/10.1007/BF02358134
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    A glasshouse progeny test for resistance to gangrene (Phoma foveata) (1990)
    Springer
    Potato research 33 (1990), S. 131-133 
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    ISSN: 1871-4528
    Keywords: disease screening ; Phoma exigua var.foveata ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Tubers were obtained from 80 glasshouse-grown seedlings of each of twelve progenies, inoculated withPhoma foveata Foister, and the mean percentage of infected tubers recorded. There was a good correlation (r=0.798) between this assessment and that made previously on field-grown tubers of eleven of the progenies. A gangrene test on glasshouse-grown tubers is suggested as a more rapid means of identifying progenies with useful levels of resistance.
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    URL: http://dx.doi.org/10.1007/BF02358138
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    Detection of strains of potato virus S by nucleic acid spot hybridization (NASH) (1990)
    Springer
    Potato research 33 (1990), S. 487-495 
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    ISSN: 1871-4528
    Keywords: PVS ; ELISA ; cDNA ; cloning ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Two complementary DNA (cDNA) clones (0.9 kb and 1.6 kb) reacting to the ordinary strain of potato virus S (PVS) were compared with single-stranded randomly primed cDNA (prepared to total genomic RNA) as probes for various strains of PVS, using the technique of nucleic acid spot hybridization (NASH). The cDNA clones detected 11 PVS isolates well, including both Andean and ordinary strains, while one of each strain was detected weakly. As little as 5 femtograms of PVS RNA could be detected. A low cross hybridization was observed with cDNA probes to PVS with potato virus M and carnation latent virus both members of the carlavirus group. No cross homology was detected with seven other potato viruses. NASH was as sensitive and specific as enzyme-linked immunosorbent assay (ELISA), with no pretreatments of crude sap being required before spotting on nitrocellulose filters. Cloned cDNA probes would be suitable for mass screening of PVS.
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    URL: http://dx.doi.org/10.1007/BF02358027
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    Influence of ambient forced-air ventilation rate on potato storage wastage (1990)
    Springer
    Potato research 33 (1990), S. 433-440 
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    ISSN: 1871-4528
    Keywords: Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Potatoes were stored in three insulated bins having ventilation rates of 0.0190, 0.0306 and 0.0417 m3/s·t. The results showed that in the climate of northern Italy potatoes can be stored successfully at ventilation rates of not less than 0.0306 m3/s·t resulting in product weight loss of less than 2.0% after 100 days' storage. The incidence of diseases and of sprouting was very low at rates of 0.0306 and 0.0417 m3/s·t, but greater at 0.019 m3/s·t because of the higher tuber temperature. Laboratory tests simulating ambient conditions confirmed the validity of a thermodynamic model simulating air-potato heat exchange.
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    URL: http://dx.doi.org/10.1007/BF02358020
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    Manipulation of tuber-size distribution of a potato crop (1990)
    Springer
    Potato research 33 (1990), S. 417-432 
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    ISSN: 1871-4528
    Keywords: stolonization ; tuberization ; tuber bulking ; size grade ; stem number ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Tuber-size distribution is regulated by many diverse, interacting mechanisms and is therefore difficult to understand and manipulate. It is determined by plant density, number of stems per plant, number of tubers per stem, and yield. Seed size and plant number per unit area are easy to control, but stem number is affected by less controllable factors. Interactions between stems of different types are important for tuber-size distribution. The hormonal regulation of stolonization and tuberization is still unknown, but under the conditions of north-west Europe the process of tuber set (which is also poorly understood) makes a greater contribution to the final number of tubers than tuberization. The total yield is also relevant, because it affects both the average tuber size and its variation. Tubers on the same stem differ in timing, rate and duration of growth. The resulting hierarchy in sink strength is not consistent over time. Several mechanisms are suggested for this hierarchy.
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    Detection of potato spindle tuber viroid by molecular hybridization and bioassay. A large-scale comparison (1990)
    Springer
    Potato research 33 (1990), S. 497-503 
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    ISSN: 1871-4528
    Keywords: DNA probe ; nick-translation ; diagnosis ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary To assess the reliability of dot-spot hybridization assay for the Potato Spindle Tuber Viroid, more than 1000 potato samples were cross-tested by biological and hybridization methods. Both methods gave similar results with a range of cultivars. The dot-spot hybridization test was reproducible with formaldehyde-denaturated cell-sap samples stored at room temperature for over 6 months. This finding means that samples can be transported from field stations to a diagnostic laboratory and allows for cross-checking of results between laboratories. The data suggest that dot-spot hybridization is suitable for breeding and quarantine purposes.
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    Loss of vitamin C (L-ascorbic acid) during long-term cold storage of Dutch table potatoes (1990)
    Springer
    Potato research 33 (1990), S. 125-130 
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    ISSN: 1871-4528
    Keywords: dehydroascorbic acid ; HPLC ; Dutch Food Composition Table ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Loss of vitamin C (L-ascorbic acid) from Dutch table potatoes during storage at 5–6°C over 8 months from November to July, was studied in two seasons. L-Ascorbic and dehydroascorbic acid were analysed by HPLC. The amount of dehydroascorbic acid was negligible. Total loss of L-ascorbic acid varied between 21 and 60%. Some potato lots lost L-ascorbic acid rapidly in the first four months, others more gradually over the whole storage period. The L-ascorbic acid levels detected were 75–150% higher in the period March–June, but 35% lower in the period December–February than those indicated by the step-wise decreases in the Dutch Food Composition Table.
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    An investigation into the factors influencing sugar levels in UK grown potatoes (cv. Record) (1990)
    Springer
    Potato research 33 (1990), S. 235-239 
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    ISSN: 1871-4528
    Keywords: processing quality ; glucose ; fructose ; sucrose ; storage ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Reducing sugar and sucrose content of potato tubers (cv. Record) grown in Tayside (northern United Kingdom (UK)) and Lincolnshire (southern UK) were monitored during the 1984 growing season and after two months storage at 10°C. Neither latitude nor agronomic factors were shown to affect sugar content. Significant correlations were found between the post storage reducing sugar content and the sugar contents measured at harvest. Regression analyses indicated that in immature tubers sucrose breakdown was responsible for reducing sugar accumulation during storage.
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    Intercellular spaces enhance potato tuber elasticity (1990)
    Springer
    Potato research 33 (1990), S. 335-340 
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    ISSN: 1871-4528
    Keywords: water saturation ; tuber injury ; lenticel perforation ; tuber maturity ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The intercellular volume within tuber tissue increases with tuber maturation. At the same time, both tuber injury after mechanical load and lentical perforation after water uptake by tubers in wet peat decreases. The degree of tuber injury is correlated with intercellular space (r=−0.667,n=16) and with water saturation of tissue (r=0.697,n=16). The tubers lose water during storage. In wet soil wilted tubers take up significantly higher amounts of water than turgid tubers, and lenticel perforation is much more frequent. Tuber maturation in autumn and low water loss during storage enhance the cushioning effect of the intercellular gas volume of tuber tissue against outside mechanical load and internal tension after water uptake.
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    Source: sink relationships in potato (Solanum tuberosum) as influenced by potassium chloride or potassium sulphate nutrition (1990)
    Springer
    Plant and soil 124 (1990), S. 287-290 
    Details
    ISSN: 1573-5036
    Keywords: cell sap ; chloride ; fertilizer ; potassium ; potato ; Solanum tuberosum L. ; solute potential ; source: sink ; sulphate ; tuber
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In pot experiments with Solanum tuberosum L. (cv Saturna) the application of KCl as compared to K2SO4 delayed tuber development. The solute composition of leaves of the KCl treated plants was significantly lower in K+ and NO3 -, but higher in Mg2+, Ca2+ and Cl-. Since the solute potential in the KCl treated plants was more negative and associated with a higher water content, a higher turgor pressure can be assumed. This could explain the enhanced shoot growth observed with KCl. Application of K2SO4, on the other hand, accelerated the development of tubers. This might result from a less competitive shoot sink in K2SO4 treated plants and a stimulated phloem loading and translocation of assimilates by higher concentrations of leaf-K.
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    Starch synthesis in potato (Solanum tuberosum) tubers: Activity of selected enzymes in dependence of potassium content in storage tissue (1990)
    Springer
    Plant and soil 124 (1990), S. 291-295 
    Details
    ISSN: 1573-5036
    Keywords: enzyme activity ; potassium nutrition ; potato ; Solanum tuberosum L. ; starch synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Starch synthesis in potato tubers grown at varied K nutrition 0.1 (K1), 0.25 (K2) and 1.0 mmol K L- nutrient solution (K3) was investigated with particular regard to the activity of selected enzymes (sucrose synthase, UDP-D-glucose pyrophosphatase, starch phosphorylase, amylases) in dependence on tuber K content. Allocation of K to the tubers was nearly the same in all treatments. The activity of enzymes related to tuber K content did not differ significantly. Starch and K content of tubers increased with progressing age, whereas a decrease was observed in growth rate, starch synthesis per day and K uptake per day. Positive correlations between the rates of K uptake, starch production and growth indicate that the dynamic phase of K supply to the tubers is of greater importance for starch synthesizing processes than the influence of total K content.
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    Zinc deficiency and pollen fertility in maize (Zea mays) (1990)
    Springer
    Plant and soil 124 (1990), S. 221-225 
    Details
    ISSN: 1573-5036
    Keywords: maize ; pollen fertility ; Zea mays L. ; zinc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Zinc deficiency decreased pollen viability in maize (Zea mays L. cv. G2) grown in sand culture. On restoring normal zinc supply to zinc-deficient plants before the pollen mother cell stage of anther development, the vegetative yield of plants and pollen fertility could be recovered to a large extent, but the recovery treatment was not effective when given after the release of microspores from the tetrads. If zinc deficiency was induced prior to microsporogenesis it did not significantly affect vegetative yield and ovule fertility, but decreased the fertility of pollen grains, even of those which visibly appeared normal. If the deficiency was induced after the release of microspores from the tetrads, not only vegetative yield and ovule fertility but pollen fertility also remained unaffected.
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    Simulation of fertilizer influence on yield and quality of potato (Solanum tuberosum) tubers by nonlinear optimization method (1990)
    Springer
    Plant and soil 124 (1990), S. 309-313 
    Details
    ISSN: 1573-5036
    Keywords: chemical compounds ; field and pot trials ; mathematical optimization model ; mineral nutrients ; potato ; Solanum tuberosum L. ; threshold values ; tuber yield
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Data of yield characteristics and the main chemical compounds of potato tubers, received from special NPK-fertilized pot and field trials, were individually evaluated by multiple regression analysis. The best suited mathematical functions, including linear, quadratic and interactive terms of N-, P- and K-concentrations in tuber dry matter, were integrated as independent variables into the models and the SUMT-method was applied for the nonlinear programming. Particular nutrient requirements could be derived from different NPK-ratios which were obtained by optimization. These ratios led to maximum tuber yield (=objective function) while at the same time observing special threshold values (e.g. nitrate) or limiting indices (=constraints) of tuber quality. By means of simulation it was possible to demonstrate characteristic differences between the effect of N-fertilization and varied N-concentrations on tuber yield and composition. Calculation of dependent variables by fixed NPK-ratios of the tubers resulted in excellent correspondence of the values for several parameters with the predictions made by both models, which were based on pot or field experiments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00009278
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  • 99
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    Effect of sub-optimal root zone temperatures at varied nutrient supply and shoot meristem temperature on growth and nutrient concentrations in maize seedlings (Zea mays L.) (1990)
    Springer
    Plant and soil 126 (1990), S. 215-225 
    Details
    ISSN: 1573-5036
    Keywords: maize ; nutrient concentration ; nutrient availability ; root growth ; root zone temperature ; shoot growth ; shoot meristem temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Maize seedlings were grown for 10 to 20 days in either nutrient solution or in soils with or without fertilizer supply. Air temperature was kept uniform for all treatments, while root zone temperature (RZT) was varied between 12 and 24°C. In some treatments the basal part of the shoot (with apical shoot meristem and zone of leaf elongation) was lifted up to separate the indirect effects of root zone temperature on shoot growth from the direct effects of temperature on the shoot meristem. Shoot and root growth were decreased by low RZT to a similar extent irrespective of the growth medium (i.e. nutrient solution, fertilized or unfertilized soil). In all culture media Ca concentration was similar or even higher in plants grown at 12 as compared to 24°. At lower RZT concentrations of N, P and K in the shoot dry matter decreased in unfertilized soil, whereas in nutrient solution and fertilized soil only the K concentration decreased. When direct temperature effects on the shoot meristem were reduced by lifting the basal part of the shoot above the temperature-controlled root zone, shoot growth at low RZT was significantly increased in nutrient solution and fertilized soil, but not in unfertilized soil. In fertilized soil and nutrient solution at low RZT the uptake of K increased to a similar extent as plant growth, and thus shoot K concentration was not reduced by increasing shoot growth rates. In contrast, uptake of N and P was not increased, resulting in significantly decreased shoot concentrations. It is concluded that shoot growth at suboptimal RZT was limited both by a direct temperature effect on shoot activity and by a reduced nutrient supply through the roots. Nutrient concentrations in the shoot tissue at low RZT were not only influenced by availability in the substrate and dilution by growth, but also by the internal demand for growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00012825
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  • 100
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    Soil physical behaviour and crop responses to tillage in lowland rice soils of varying clay content (1990)
    Springer
    Plant and soil 126 (1990), S. 227-235 
    Details
    ISSN: 1573-5036
    Keywords: Oryza sativa ; rice ; root length density ; soil impedance ; tillage ; water stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The influence of various tillage methods on two wetland rice soils in the Philippines is reported. The soils differed principally in clay content, 38% for the clay loam (clayey, mixed isohyperthermic Entic Hapludoll) while 56% for the clay (clayey, mixed noncalcareous, isohyperthermic Andaqueptic Haplaquoll). This had a marked effect on their response to tillage and varying water regime. The clay soil, under field conditions, showed little change in pore size distribution or soil water behaviour with different tillage methods. Crop (Rice, Oryza sativa L., var. IR20) yields were unaffected by tillage. In contrast, tillage effects were very marked in the clay loam soil, which consisted of a greenhouse and a field trial. In the greenhouse, which experienced severe dry periods, wet tillage not only increased the moisture retentivity but also the soil impedance at soil matric potential (ψ)〈−0.01 MPa. Seasonal average ψ was 〈−1 MPa. Root length density decreased by 39% with dry tillage and by 56% with wet tillage compared with zero tillage. Grain yield however, did not vary with soil treatment. In the field, which experienced moderate dry spells, ψ varied between −0.13 and −0.48 MPa. Root length density was significantly reduced at soil impedance 〉0.75 MPa. Wet tillage increased soil moisture storage which minimized the soil impedance during the dry cycle more effectively than did dry tillage. The crop performed best under wet tillage and least under zero tillage. Wet tillage in this soil was more effective under moderate than under severe water stress conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00012826
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