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  • Articles  (130)
  • nitrogen fixation  (74)
  • rice  (56)
  • 1985-1989  (130)
  • 1965-1969
  • Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition  (129)
  • Geosciences  (1)
  • Economics
  • Energy, Environment Protection, Nuclear Power Engineering
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  • Articles  (130)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Nutrient cycling in agroecosystems 16 (1988), S. 257-272 
    ISSN: 1573-0867
    Keywords: NH3-volatilization ; nitrogen-transformations ; denitrification ; nitrogen leaching ; nitrogen-application time ; rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Ammonia volatilization losses and other N transformations were studied in drill sown rice bays fertilized with urea at various times between permanent flooding (PF) and panicle initiation (PI). Ammonia loss was measured directly with flow chambers and indirectly through application of Freney et al.'s (1985) model. Both techniques indicated that ammonia volatilization was negligible from fields fertilized immediately before PF. Applying 100 kg urea-N ha−1 to floodwater one day after flooding significantly increased floodwater ammoniacal-N and urea-N content, however the concentrations fell rapidly over the following five days. Fertilizer-N dissolved in the floodwater was in the urea rather than the ammoniacal-N form, indicating slow hydrolysis until it moved into the soil. Floodwater on plots receiving urea one day after PF frequently had more than double the NO3-N concentration of plots fertilized before flooding. Applying up to 140 kg urea-N ha−1 at PI increased floodwater ammoniacal-N concentrations from almost zero to over 27 g m−3, but three days after fertilization there was less than 3 g m−3 present. Fertilization also increased NH4-N concentration in the top 40 mm of soil. Higher ammoniacal-N concentration at PI suggests higher urease activity. Floodwater pH at PI was low, with a mean daily maximum of 7.8 and this reduced ammonia loss to less than 1% of the applied N. The results indicate that volatilization from fields fertilized prior to PF is minimal because of the low floodwater pH and ammoniacal-N concentration, while low floodwater pH restricts volatilization from fields topdressed at PI.
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  • 2
    Electronic Resource
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    Springer
    Nutrient cycling in agroecosystems 17 (1988), S. 47-59 
    ISSN: 1573-0867
    Keywords: Azolla pinnata (Bangkok) ; blue-green algae (BGA) ; N accumulation ; nitrogen fertilizer ; rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Application of higher levels (60 and 90 kg N ha−1) of nitrogen fertilizer (Urea) inhibited the growth ofAzolla pinnata (Bangkok) and blue-green algae (BGA) though the reduction was more in BGA thanAzolla. Inoculation of 500 kg ha−1 of freshAzolla 10 days after transplanting (DAT) in the rice fields receiving 30, 60 and 90 kg N ha−1 as urea produced an average of 16.5, 15.0 and 13.0 t ha−1 fresh biomass ofAzolla at 30 DAT, which contained 31, 31 and 27 kg N ha−1, respectively. The dry mixture of BGA (60%Aulosira, 35%Gloeotrichia and 5% other BGA on fresh weight basis) inoculated in rice field 3 DAT at a rate of 10 kg ha−1 showed a mat formation at 80 DAT with an average fresh biomass of 8.0, 5.8 and 4.2 t ha−1 containing 22, 17 and 12 kg N ha−1, respectively with those N fertilizer doses. Application ofAzolla showed positive responses to rice crop by increasing the panicle number and weight, grain and straw yields and nitrogen uptake in rice significantly at all the levels of chemical nitrogen. But, the BGA inoculation had a significant effect on the grain and straw yields only during the dry season in the treatment where 30 kg N was applied. During the wet season and in the other treatments performed during the dry season no significant increase in yields, yield components and N uptake were observed with BGA. The intercropping ofAzolla and rice in combination with 30, 60 and 90 kg N ha−1 as urea showed the yields, yield attributes and nitrogen uptake in rice at par with those obtained by applying 60, 90 and 120 kg N ha−1 as urea, respectively but, the BGA did not. The analysis of soil from rice field after harvest showed thatAzolla and BGA intercropping with rice in combination with chemical fertilizer significantly increased the organic carbon, available phosphorus and total nitrogen of soil.
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  • 3
    ISSN: 1573-0867
    Keywords: farmyard manure ; maize ; nitrogen ; phosphorus ; rice ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Field experiments with rice-wheat rotation were conducted during five consecutive years on a coarse-textured low organic matter soil. By amending the soil with 12t FYM ha−1, the yield of wetland rice in the absence of fertilizers was increased by 32 per cent. Application of 80 kg N ha−1 as urea could increase the grain yield of rice equivalent to 120 kg N ha−1 on the unamended soil. Although the soil under test was low in Olsen's P, rice did not respond to the application of phosphorus on both amended and unamended soils. For producing equivalent grain yield, fertilizer requirement of maize grown on soils amended with 6 and 12 t FYM ha−1 could be reduced, respectively to 50 and 25 per cent of the dose recommended for unamended soil (120 kg N + 26.2 kg P + 25 kg K ha−1). Grain yield of wheat grown after rice on soils amended with FYM was significantly higher than that obtained on unamended soil. In contrast, grain yield of wheat which followed maize did not differ significantly on amended or unamended soils.
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  • 4
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    Nutrient cycling in agroecosystems 20 (1989), S. 27-32 
    ISSN: 1573-0867
    Keywords: Cropping system ; phosphorus ; rice ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A long term field experiment was conducted on a sandy loam soil from 1983 to 1987 to determine how to best apply phosphorus fertilizer in a rice-wheat cropping system. The treatments included 9 combinations of phosphorus application either to both rice and wheat or to rice or wheat alone. Direct application of phosphorus at 13 kg/ha to both the crops resulted in significantly higher total productivity of the rice-wheat cropping system as compared with 26 kg P/ha applied either to rice or wheat alone. Phosphorus at 13 kg/ha for rice and 26 kg/ha for wheat was as efficient as 13 kg P/ha for rice and 13 kg P/ha for wheat. The higher rate of P (26 kg/ha) applied to both rice and wheat resulted a decline in the total productivity. The residual effects of phosphorus applied to either rice or wheat were significant to the succeeding crop but was inferior to its direct application. Phosphorus increased the leaf area index, chlorophyll content of leaves, and interception of more photosynthetically active radiation (PAR) which resulted in increased grain yield of rice and wheat. Phosphorus status of the surface soil declined markedly, in the absence of P application from 15.4 to 6.4 kg P/ha. Phosphorus applied at 26 kg P/ha to both the crops resulted a build up of the available P status of soil. Phosphorus application at 13 kg/ha to both rice and wheat maintained the phosphorus status of the soil at original level.
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  • 5
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    Springer
    Nutrient cycling in agroecosystems 21 (1989), S. 109-111 
    ISSN: 1573-0867
    Keywords: Legumes ; nitrogen fixation ; tall fescue ; white clover ; nitrogen fertilizer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract White clover was compared against five rates of nitrogen fertilizer (NH4NO3) as sources of N for tall fescue over a 3 year period. The white clover-tall fescue combination produced as much forage as tall fescue alone fertilized with 132–198 kg N ha−1 in the first 2 years. However, in the third year the white clover-tall fescue combination only produced as much forage as tall fescue alone fertilized with 0–66 kg N ha−1 as a result of a large decline in the stand of white clover. Tall fescue alone showed a significant response to fertilization up to the maximum rate of 264 kg N ha−1. Tall fescue fertilized with 264 kg N ha−1 produced significantly more forage than the white clover-tall fescue combination in all 3 years.
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  • 6
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    Nutrient cycling in agroecosystems 21 (1989), S. 113-123 
    ISSN: 1573-0867
    Keywords: Nitrogen use ; farmer risk aversion ; rice ; Asia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Year to year variability in nitrogen response is widely believed to be responsible for low levels of fertilizer application by risk averse farmers. Certain authors have claimed that production risk is not responsible for sub-optimal applications of fertilizer. Since these studies estimated fertilizer response in irrigated areas or in simulated rainfed areas in experiment stations they may have underestimated the degree of risk faced by the majority of farmers. This study seeks to address this issue of risk under farmers' conditions by using data from rainfed farmers fields in a risky rice growing area of the Philippines. Long term distributions of factors responsible for temporal variability in N-response, such as moisture stress and typhoons, are derived by using a rainfall simulator and a water balance model. These distributions are combined with a hetereoscedastic nitrogen response function to simulate long term yield distributions at different N-rates. The application of risk averse and risk neutral decision making models shows that risk aversion reduces fertilizer application by only 7–9%. These results occur because as N-rates increase, the benefits from increased average profits outweigh the disadvantages of increased variability in profits. These findings provide additional evidence to support the emerging consensus that the impact of risk aversion on fertilizer use is much smaller than previously believed.
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  • 7
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    Nutrient cycling in agroecosystems 9 (1986), S. 149-160 
    ISSN: 1573-0867
    Keywords: Nitrogen fertilizers ; rice ; fertilizer efficiency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The efficiency of nitrogen (N) fertilizer products and practices currently used on rice is low, and improving this efficiency would be very beneficial to rice-growing countries. The development of new N fertilizers is best achieved by following a logical sequence of testing and evaluation procedures in a variety of settings from the laboratory to the farmer's field. Novel N fertilizers currently at various stages of testing include urea supergranules for deep placement, urea coated with various materials to control the N release rate, mixtures of a urease inhibitor with urea to reduce losses, and organic N sources other than urea.
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  • 8
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    Nutrient cycling in agroecosystems 10 (1986), S. 43-58 
    ISSN: 1573-0867
    Keywords: Northern Nigeria ; phosphate ; potassium ; nutrient uptake ; nitrogen fixation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Up until now, potash fertilization has not been part of the recommended practices for groundnut production in Nigeria and only low levels of P are recommended in line with the level of agricultural technology available to the farmer. The change from the traditional non-intensive farming practice to continuous intensive cultivation coupled with the introduction of better yielding/more-nutrient demanding crop varieties have led to a deficiency of a number of nutrients. Field experiments were carried out for 5 years (repeated on the same sites) at 8 locations in northern Nigeria to evaluate the effect of four levels of phosphorus (0, 8, 16 and 24 kg P ha−1) and three levels of potassium (0, 20, and 40 kg K ha−1) on yield and related parameters in groundnut. Soils at the various sites were essentially loamy sands with low levels of organic carbon and cation exchange capacity. The yield levels in the Guinea savannah were generally higher than those in the Sudan savannah but the response pattern was the same. There was significant response to applied P up to 24 kg P ha−1. Potash applied at 20 kg K ha−1 produced significantly higher pod yields than the control plots, but higher rates of applied K did not result in any further significant yield increase, although there was a clear consistent trend towards higher yields as the K rates increased. Phosphate X potash interaction had no significant effect on yield. Except for K, the uptake of all nutrients were significantly increased by P levels. However, only the K content of haulms and the N content of kernels were significantly increased by K application. On the average, about 58% of N, 68% of P, 19% of K, 5% of Ca and 22% of Mg were contained in the kernels while 27% of N, 23% of P, 64% of K, 83% of Ca and 69% of Mg were contained in the haulms. The implication of this is that the complete removal of groundnut residue will deplete the soil cation reverves rapidly unless these losses are compensated through fertilizer use.
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  • 9
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    Nutrient cycling in agroecosystems 10 (1986), S. 119-133 
    ISSN: 1573-0867
    Keywords: ammonium sulphate ; fertilizer-N recovery ; NH3 volatilization ; rice ; urea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In a pot experiment it was established that NH4 volatilization losses were larger with urea than with ammonium sulphate used as a basal fertilizer for lowland rice. The difference arose from the pH-increasing effect of urea in the floodwater. This rise in pH promoted the growth of algae which in turn were responsible for large diurnal fluctuations in the pH of the floodwater thus enhancing the loss of NH3 during daytime. Ammonium sulphate lowered the pH of the water which suppressed the growth of algae. Once the rice canopy had closed, the algal population declined and the diurnal pH fluctuations largely disappeared. Urea as a topdressing was found to be less liable to give rise to NH3 volatilization than when added as basal dressing. The highest N recovery was obtained with ammonium sulphate used as basal dressing and urea as topdressing. Working a basal dressing into the soil improves the fertilizer-N recovery of urea-N, but not of ammonium sulphate-N, the latter being already high without soil incorporation.
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  • 10
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    Nutrient cycling in agroecosystems 16 (1988), S. 37-45 
    ISSN: 1573-0867
    Keywords: Leaching losses ; N movement ; deep placement ; rice ; soil texture ; urea supergranule
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In a glasshouse experiment, the periodic movement, loss and uptake of N by lowland rice fertilized with point-placed urea supergranule (USG) was studied in two soils differing in texture. Movement of urea-N, NH 4 + -N and NO 3 - -N was significantly faster in Patharchatta sandy loam (Typic Hapludoll) than in Beni silty clay loam (Aquic Hapludoll) and was mostly downward with peak concentration near the placement site. Nitrogen in leachate was higher in Patharchatta sandy loam than in Beni silty clay loam. About 60–70% of leaching of urea-N took place within 2 days of USG placement. The leaching of NH 4 + -N and NO 3 - -N increased till 14 and 21 days of USG placement in Patharchatta sandy loam and Beni silty clay loam, respectively. Nitrogen leached through urea, NH 4 + and NO 3 - forms was, respectively, 64, 25 and 25% higher from sandy loam. During 49 days, 49 and 32% of the applied N was recovered by rice plants from silty clay loam and sandy loam, respectively.
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  • 11
    ISSN: 1573-0867
    Keywords: calcium ammonium nitrate ; calcium cyanamide ; humid tropics ; maize ; nitrate leaching ; rice ; ultisol ; urea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Leaching loss of N applied as calcium cyanamide (CaCN2 — 19% N), urea and calcium ammonium nitrate (CAN — 26% N) to a coarse textured, kaolinitic ultisol profile was studied in the laboratory using undisturbed soil columns. The soil columns were leached with an amount of water equivalent to the annual rainfall of the sampling site (2420mm) using a rainfall simulator over a period of 42 days. The ‘leachability’ of the three N fertilizers differed greatly and followed the order of CAN 〉 urea 〉 CaCN2. Most of the N lost through leaching was in NO3 form. Calcium cyanamide lost only 3% of applied N. Breakdown of CaCN2 to NH4 was incomplete (64%) and nitrification in the soil was inhibited resulting in negligible leaching loss. Nitrogen retained in the soil columns after the leaching cycle was mainly in ammoniacal form irrespective of source of N used. Effectiveness of CaCN2 as a N source was also studied in a greenhouse experiment with maize (Zea mays) and upland rice (Oryza sativa) as testing crops. Calcium cyanamide applied one week before sowing of crops was as effective as CAN and urea under conditions of no N leaching. When applied at the time of planting and two or more weeks before planting gave lower dry matter yields and N uptake than CAN and urea.
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  • 12
    ISSN: 1573-5036
    Keywords: fertilization ; nitrate reductase activity ; paddy soil ; rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract When following the pattern of the disappearance of NH 4 + −N from ammonium sulfate applied to the flooded soil-rice plant system (field and greenhouse experiments) during a growing season, it was observed that the lowest NH 4 + −N level coincided with the highest value of NR activity in the leaves. Nitrate was detected in both the root and shoot systems of the rice plants and autotrophic nitrifiers (Nitrosomonas and Nitrobacter) were particularly abundant. Since it was also demonstrated in this work that the NR activity of rice plants grown with nitrate fertilization (growth chamber culture experiments) was inducible by its substrate, it can be assumed that NH 4 + −N oxidation takes place in the water-logged soil studied. Therefore, the occurrence of the nitrification process following NH 4 + −N fertilizer application can be predicted by thein vitro orin situ evaluation of the NR activity of the rice leaf as an indicator.
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  • 13
    ISSN: 1573-5036
    Keywords: Alnus ; compatibility ; Frankia ; grafting technique ; nitrogen fixation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Two alder species,Alnus glutinosa (L.) Gaertn. andAlnus incana (L) Moench, were inoculated with a Sp+ Frankia homogenate obtained fromA. incana root nodules. This inoculum formed effective nodules on the original host plant and ineffective nodules onA. glutinosa. Grafts between the two alder species were made to determine which part of the plant is involved in this phenomenon. The results obtained indicate that the compatibility between Alnus andFrankia is restricted to the root system.
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  • 14
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    Plant and soil 114 (1989), S. 45-52 
    ISSN: 1573-5036
    Keywords: cultivar variability ; Glomus fasciculatum ; growth response ; nitrogen fixation ; nutrient uptake ; rhizobium ; Vigna unguiculata
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Vesicular-arbuscular mycorrhizal (VAM) associations often vary according to the abundance of available soil phosphorus (P). Therefore, understanding the response of crop plants to colonization by VAM fungi necessitates the study of the response of colonized and noncolonized plants, from a range of cultivars, to differing levels of P. Cowpea is grown throughout the world, often on impoverished soils in which it can benefit from formation of mycorrhizae. The present study was conducted to determine the response of four cultivars of cowpea (Vigna unguiculata (L.) Walp.), varying in nitrogen fixation capacity, to inoculation withGlomus fasciculatum at four levels of added P in the rooting medium. In a greenhouse experiment, four cowpea cultivars, Mississippi Silver, Brown Crowder, Six Week Browneye and MI 35, were grown with and without the mycorrhizal fungus at four levels of added P, 0, 10, 20 and 30 ppm. Root colonization (%) was negatively correlated with P content of the growth medium and shoot P concentration. Intraspecific variability was shown for shoot dry weight and leaf area in response to inoculation withG. fasciculatum at different P levels. The range of P required in the growth medium which allowed benefit fromG. fasciculatum was identified for individual cultivars using shoot dry weight and leaf area, and collectively across cultivars for other parameters.
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  • 15
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    Plant and soil 114 (1989), S. 69-74 
    ISSN: 1573-5036
    Keywords: water stress ; nitrogen fixation ; nodulation ; Vigna unguiculata ; Arachis hypogaea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effect of water deficit on nodulation, N2 fixation, photosynthesis, and total soluble sugars and leghemoglobin in nodules was investigated in cowpea and groundnut. Nitrogenase activity completely ceased in cowpea with a decrease in leaf water potential (ψ leaf) from −0.4 MPa to −0.9 MPa, while in groundnut it continued down to −1.7 MPa. With increasing water stress, the acetylene reduction activity (ARA) declined very sharply in cowpea, but ARA gradually decreased in groundnut. Even with mild water stress (Δψ leaf of 0.2 MPa), nodule fresh weight declined 50% in cowpea partly due to a severe nodule shedding whereas nodule fresh weight declined in groundnut only whenψ leaf decreased by 1.0 MPa. No nodule shedding was noticed even at a higher stress level in groundnut. Photosynthesis and stomatal conductance were also more stable in groundnut than in cowpea under water stress. There was a sharp increase in total soluble sugars and leghemoglobin in the nodules of groundut with water stress, but no definite trend could be found in cowpea.
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  • 16
    ISSN: 1573-5036
    Keywords: indigenous soil rhizobia ; Medicago sativa L. ; nitrogen fixation ; regrowth cycles ; Rhizobium meliloti ; symbiotic effectiveness
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Studies were conducted to evaluate whether field-grown cultivars of alfalfa (Medicago sativa L.) nodulate differentially with members of a soil population ofRhizobium meliloti, and to determine the influence of the dominant nodule occupants on N2-dependent growth of the same cultivars under greenhouse conditions. Nodules were sampled from four replicate plots of ‘Vernal’, ‘Anchor’, and ‘Saranac’ alfalfa, and the isolates analysed serologically. Results from agglutination tests identified serogroup 31 as a dominant nodule occupant. A significant cultivar effect was observed, with a greater and more consistent occupancy rate by serogroup 31 across the replicates on Vernal (60%) compared to Anchor (24%) or Saranac (36%). The symbiotic effectiveness of the parent isolate of serogroup 31 was evaluated on each cultivar over four successive harvests in a greenhouse study. Significant cultivar x N source interactions for herbage dry weight resulted following the second harvest. Of the three cultivars, only inoculated Vernal responded with an increase in shoot dry weight and N2 assimilated relative to N supplemented plants between harvests two and three. In separate greenhouse experiments, field isolates of serogroup 31 from nodules on Vernal produced homogeneous, effective responses both on Vernal and Anchor. In contrast, serogroup 31 field isolates from Anchor nodules were highly heterogeneous in effectiveness on the parent host, with poorly effective isolates being substantially more effective on Vernal. The data indicate that attention should be given to the potential impact of the indigenousR. meliloti population upon cultivar ranking at specific field locations, and also to strain-cultivar idiosyncracies when carrying out physiological sutidies of regrowth characteristics.
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  • 17
    ISSN: 1573-5036
    Keywords: chickpea ; phosphorus ; nitrogen fixation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Application of phosphorus at 40, 60, 80 and 100 kg P2O5 ha−1 in the presence of a uniform dressing of nitrogen (N) and potash (K2O) each applied at 20 and 24 kg ha−1 to chickpea (CM-88) grown in sandy loam soil in a replicated field experiment improved the nodulation response of the crop, increased its grain yield (ka ha−1) by 18, 59, 40 and 14 percent, biomass yield (ka ha−1) by 32, 32, 54 and 14 percent, biomass N (kg ha−1) by 31, 48, 49, 19 percent, and biomass P (kg ha−1) by 26, 40, 41 and 11 percent, respectively. The effect of phosphorus on the nitrogenase activity of the excised roots of chickpea was, however, inconsistent.
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  • 18
    ISSN: 1573-5036
    Keywords: acetylene reduction ; Azospirillum ; brown-rot ; nitrogen fixation ; white-rot
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Nitrogen fixation rates, as estimated by the acetylene reduction technique, were determined in conifer wood litter being decayed by brown- and white-rot fungi. Average ethylene production rates were significantly higher in white-rotted wood (15.1 nmol g−1 day−1) than in brown-rotted wood (2.3 nmol g−1 day−1). This difference may be related to a higher soluble sugar content in white-versus brown-rotted wood. The nitrogen-fixing bacteriumAzospirillum was not detected in any of the decaying wood samples examined. Greater nitrogen additions from nitrogen-fixing bacteria may be a factor in the more rapid white-rot decay of hardwood litter, as compared to the slower brown-rot decay of conifer wood.
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  • 19
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    Plant and soil 118 (1989), S. 125-132 
    ISSN: 1573-5036
    Keywords: Allocasuarina sp. ; Casuarina sp. ; nitrogen fixation ; phosphorus fertilization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract To examine how soil phosphorus status affects nitrogen fixation by the Casuarinaceae —Frankia symbiosis,Casuarina equisetifolia and two species ofAllocasuarina (A. torulosa andA. littoralis) inoculated or fertilized with KNO3 were grown in pots in an acid soil at 4 soil phosphate levels. InoculatedC. equisetifolia nodulated well by 12 weeks after planting and the numbers and weight of nodules increased markedly with phosphorus addition. Growth ofC. equisetifolia dependent on symbiotically fixed nitrogen was more sensitive to low levels of phosphorus (30 mg kg−1 soil) than was growth of seedings supplied with combined nitrogen; at higher levels of phosphorus, the growth response curves were similar for both nitrogen fertilized and inoculated plants. The interaction between phosphorus and nitrogen treatments (inoculated and nitrogen fertilized) demonstrated that there was a greater requirement of phosphorus for symbiotic nitrogen fixation than for plant growth when soil phosphorus was low. WithAllocasuarina species, large plant to plant variation in nodulation occurred both within pots and between replicates. This result suggests genetic variation in nodulation withinAllocasuarina species. Nodulation ofAllocasuarina species did not start until 16 weeks after planting and no growth response due toFrankia inoculation was obtained at the time of harvest. Addition of nitrogen starter is suggested to boost plant growth before the establishment of the symbiosis. Growth ofAllocasuarina species fertilized with nitrogen responded to increasing levels of phosphorus up to 90 mg P/kg soil after which it declined by 69% forA. littoralis. The decrease in shoot weight ofA. littoralis, A. torulosa, C. equisetifolia andC. cunninghamiana at high phosphorus was confirmed in a sand culture experiment, and may be atributable to phosphorus toxicity.
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  • 20
    ISSN: 1573-5036
    Keywords: actinorhizae ; Casuarina cunninghamiana ; Frankia ; nitrogen fixation ; oxygen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of time after exposure to acetylene and of nodule excision were examined using a flow-through system. After a transient depression in the rate of acetylene reduction that began about 1.5 min after exposure to acetylene, the rate recovered to 98% of the initial maximum value after 40 min. After nodule excision the rate stabilized to 90% of the initial maximum value observed in the intact plant. Excised nodules, measured at 6-min intervals in a closed system, with frequent changes of the gas mixture, were used for the remaining experiments. Acetylene reduction by the nodules increased rapidly as temperature was increased between 6 and 26°C. Between 26 and 36°C there was relatively little effect of temperature on acetylene reduction. Nodules and cultures ofFrankia were compared with respect to the effect of temperature and pO2 (partial pressure of oxygen) on oxygen uptake. Cultures ofFrankia were grown on a nitrogen-free medium at either 0.3 kPa O2 (vesicles absent) or 20 kPa O2 (vesicles present). Oxygen uptake by nodules (vesicles absent) and by vesicle-containing cultures was strongly dependent on pO2 at values below 20 kPa. This suggests the presence of a barrier to oxygen diffusion. Oxygen uptake was dependent on temperature as well as on pO2, but the Q10 was much larger for the cultures than for the nodules. This suggests that vesicles or related structures are not the source of the diffusion barrier in Casuarina nodules. Respiration by cultures ofFrankia lacking vesicles became O2-saturated at low pO2 values. Thus these cultures did not have a significant diffusion barrier. From these results it is concluded that nodules ofCasuarina cunninghamiana have a barrier to oxygen diffusion supplied by the host tissue and not byFrankia.
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  • 21
    ISSN: 1573-5036
    Keywords: antibiosis ; bacterization ; biological control ; rice ; sheath-blight
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Strains of fluorescent and nonfluorescent bacteria that were isolated from rice rhizospheres of Southern India and showed antagonism towardsRhizoctonia solani were evaluated for biological control of rice sheath-blight (ShB). Efficient strains of bacteria inhibited mycelial growth ofR. solani, affected sclerotial viabilityin vitro and protected IR 20 and TKM 9 rice seedlings from infection byR. solani in greenhouse tests. Pretreatment of sclerotia in bacterial suspensions resulted in reductions in ShB lesion sizes up to 31 to 44% in IR20 and 58 to 74% in TKM 9 rice. In field plots, IR 50 and TKM 9 rice plants raised from bacterized seeds had 65 to 72% less ShB than those plants from untreated seeds.
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  • 22
    ISSN: 1573-5036
    Keywords: Azolla caroliniana ; Azolla pinnata ; nitrogen fixation ; Oryza sativa ; phosphate fertilizer ; rice yield
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The response of rice toAzolla caroliniana, newly introduced in India, was compared with the reponse to the local isolate ofAzolla pinnata at varying rates of phosphate fertilizer (4.4–8.8 kg P ha−1) during a wet and a dry season. Fresh weight, dry weight and fixed N were more for both species 21 DAI (days after inoculation) than 14 DAI, but acetylene reduction activity (ARA) was higher 14 DAI than 21 DAI. Dry weight of Azolla and fixed N were less 14 DAI forA. caroliniana than forA. pinnata during the wet season. Twenty-one DAI, fresh weight ofA. caroliniana was 62.1 and 27.6% higher than that ofA. pinnata during the wet and dry season, respectively. However, dry weight and fixed N were more 21 DAI inA. caroliniana than inA. pinnata during only the wet season. The ARA was higher inA. caroliniana both 14 and 21 DAI, irrespective of season. The presence of either species in the rice field increased grain yield, straw yield, number of panicles m−2, number of grains per panicle and reduced percentage sterility during both the wet and the dry season. Phosphate application significantly increased fresh weight, dry weight, ARA and fixed N for both species as well as grain and straw yields of rice. The responses to phosphate fertilizer were similar for both Azolla species and for rice grown with either one of the Azolla species.
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  • 23
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    Plant and soil 114 (1989), S. 235-241 
    ISSN: 1573-5036
    Keywords: Azospirillum ; Cocos nucifera ; intercrops ; nitrogen fixation ; plantation crops ; tetrazolium reduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Occurrence of Azospirillum was investigated in coconut-based farming systems, such as high-density multispecies cropping (15 crops), multi-storeyed cropping (3 crops), mixed cropping with tea and coffee (2 crops), intercropping with tropical tubers (5 crops), mixed farming with grasses (3 crops) and in 3 crops, arecanut,Mimosa invisa and sugarcane from other plots. A total of 26 plantation crops and intercrops were included in the study. Incidence of Azospirillum was determined by 2,3,5-triphenyl-tetrazolium chloride reduction and by culturing root fragments in N-free semisolid malate medium. Root samples from guava, mango and mimosa did not show any tetrazolium reduction or sub-surface pellicular growth. The extent of occurrence of Azospirillum seemed to depend upon the crop combinations. In a mixed farming system where guinea grass was one of the component crops, more root fragments of coconut and pepper demonstrated tetrazolium reduction activity than when guinea grass was absent.Azospirillum lipoferum andA. brasilense constituted 42% and 45% of the isolates, respectively, in the coconut-based cropping systems. Isolates from guinea grass, sugarcane and jackfruit exhibited higher nitrogenase (C2H2 reduction) than those isolated from plantation crops, tuber crops and spices. The large variation in the extent of association and nitrogenase activity of isolates from different crops indicated the need for inoculation with efficient cultures in a number of crops in coconut-based cropping systems.
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  • 24
    ISSN: 1573-5036
    Keywords: Azolla pinnata ; biomass ; critical P level ; flooded soil ; N2-fixation ; P fertilizer ; P transfer ; rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A field experiment was conducted at the Bangladesh Rice Research Institute, Joydebpur, Dhaka during the late wet season. Basal application of P at both 5 and 10 kg ha−1 significantly increased total biomass production and nitrogen fixation byAzolla pinnata R. Brown (local strain). Addition of both 5 and 10 kg P ha−1 in equal splits at inoculation and at six day intervals thereafter during growth periods of 12, 24 and 36 days increased biomass production and nitrogen fixation by Azolla over that attained with the basal application. Biomass and nitrogen fixation using a split application of 5 kg P ha−1 exceeded that attained with basal application of 10 kg P ha−1 and split application of 10 kg P ha−1 resulted in 0.58, 11.2, and 18.3 t ha−1 more biomass, and 0.47, 18.9, and 18.3 more kg fixed N ha−1 at 12, 24 and 36 days, respectively, than the same amount applied as a basal application. Analyses indicated that the critical level of dry weight P in Azolla for sustained growth was in the range of 0.15–0.17%. Compared with the control, where no P was added, and additional 30 and 36 kg N ha−1 were fixed after 24 and 36 days, respectively, when P was provided at 10 kg ha−1 using a split application. A separate field study showed that flooded rice plants received P from incorporated Azolla with about 28% of the P present in the supplied Azolla being incorporated into the rice plants.
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  • 25
    ISSN: 1573-5036
    Keywords: nitrogen fixation ; nodules ; stomatal resistance ; water potential
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The response to water stress was studied on white clover grown hydroponically. Two varieties (Crau and Huia) were both subjected to a moderate and a more-severe stress, induced by polyethylene glycol (10 and 20% respectively), in the presence of a nutrient solution poor in potassium (K1=0.005 mM), or abundantly supplied (K2=5mM). Dawn water potential and nitrogen fixation (acetylene reduction activity) decreased with the increasing stress. Conversely, the stomatal resistance increased whenosmoticum was added. Crau had a lower stomatal resistance to the deficit, than did Huia. In relation with the K supply, treatment K2 confirmed the superiority of Crau. Crau also showed greater nodule mass and number than Huia. The data show relationships between dawn water potential, stomatal resistance and nitrogen fixation activity.
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  • 26
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    Biogeochemistry 8 (1989), S. 25-37 
    ISSN: 1573-515X
    Keywords: nitrogen budget ; denitrification ; nitrogen fixation ; wetlands
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Nitrogen flux data was synthesized in developing a nitrogen flow budget for a Louisiana Barataria BasinSpartina alterniflora salt marsh. Results demonstrate the importance of spatial consideration in developing a nitrogen budget for coastal marshes. Using a mass balance approach nitrogen inputs balanced nitrogen sinks or losses from a marsh soil-plant system with a specific rooting depth. However, per unit areas on a local scale, marshes serve as a large sink for nitrogen due to rapid accretion which removes 17.O g N m−2yr−1 through subsidence below the root zone. On a larger spatial scale (regional) it is shown that the marshes do not serve as a large nitrogen sink. The rapid marsh deterioration currently occurring in the rapidly subsiding marshes of the Mississippi River deltaic plain account for a net regional loss of 12.5 g N m−2yr−1. Thus, regionally the net sink is equivalent to only 5 g N m−2yr−1 as compared to 17.0 g N m−2yr−1 on a local scale.
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  • 27
    ISSN: 1573-5036
    Keywords: nitrogen fixation ; plant production
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 28
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    Plant and soil 108 (1988), S. 7-14 
    ISSN: 1573-5036
    Keywords: applications ; biochemistry ; discoveries ; nitrogen fixation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The discoveries of Hellriegel and Wilfarth ended the period of controversy about the existence of biological N2 fixation and launched a period featuring the agronomic application of the inoculation of legumes. Serious studies of the biochemistry of N2 fixation started in the late 1920's, and defined some of the basic properties of the N2-fixing system. Application of15N as a tracer gave definitive evidence for the role of ammonia as the key intermediate in biological N2 fixation. It was demonstrated in the 1950's and 1960's that nitrogenase could reduce substrates other than N2. With the achievement of consistent cell-free N2 fixation it was possible to resolve the nitrogenase system into two proteins, electron donors, and ATP-hydrolyzing and regenerating systems. The sequence of electron transfer was established. Recently, studies of the genetics of the nitrogenase system have defined in detail how the system is assembled and controlled.
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  • 29
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    Plant and soil 108 (1988), S. 53-65 
    ISSN: 1573-5036
    Keywords: Azospirillum ; cereals ; grasses ; inoculation response ; nitrate reductase ; nitrogen fixation ; strain specificity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Over the last few years research in the area of biological nitrogen fixation (BNF) associated with cereals and grasses has become divided into two areas. On the one hand there have been a large number of reports of responses of field-grown plants to inoculation with N2-fixing bacteria, principallyAzospirillum spp. On the other hand there have been several reports of significant contributions of associated BNF to the nutrition of several crops, including wetland rice, sugar cane and some forage grasses. However, where BNF contributions have definitely been established no certain information is available as to the diazotrophic organisms responsible. Furthermore, certain recent reports indicate that, at least in some cases, responses of plants to inoculation withAzospirillum spp. have been shown not to be due to BNF contributions. In this paper we review some recent progress in this field, particularly at our institute in Rio de Janeiro, concerning specificity of selected Azospirillum strains in the infection of cereal roots and the promotion of responses in the host plants. The possible mechanisms of plant response are discussed including the possibility that plant growth substances or bacterial nitrate reductase are involved. The application of15N and N balance techniques to the quantification of plant associated BNF are considered and the possible strategies that may be adopted to further the understanding of true N2-fixing plant/diazotroph associations. The recent discovery of many more plant-associated N2-fixing bacteria suggests that further research in this area may eventually lead to the development of such associations with applications for agricultural productivity.
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  • 30
    ISSN: 1573-5036
    Keywords: Actinorhiza ; effectiveness ; nitrogen fixation ; nutrition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Growth responses ofCasuarina cunninghamiana to inoculation withFrankia are described in unsterilized field soils at three sites. At Mt Crawford, South Australia, seedlings of three provenances ofC. cunninghamiana were inoculated with a singleFrankia source just prior to planting out. Forty-four months after planting, inoculation had more than doubled wood production by twoC. cunninghamiana provenances, whilst a third provenance grew poorly and did not respond to inoculation. In Zimbabwe, seedlings of one provenance ofC. cunninghamiana were inoculated in the nursery with one of four differentFrankia strains. In an N deficient soil at Kadoma, three of theseFrankia increased tree height 14 months after planting by between 50% and 70% in comparison to the uninoculated seedlings. The fourthFrankia strain resulted in increased tree height to three times that of the uninoculated controls and up to double that of the other threeFrankia strains. At Gympie, Queensland, Australia, seedlings ofC. cunninghamiana raised open-rooted in a nursery bed were inoculated withFrankia seventeen weeks before planting out. During the 22 months following planting in the field, tree growth was limited by soil P status and there was no response in tree height or stem diameter to inoculation withFrankia or to N fertilizer unless P was applied. In the presence of added P there was a significant response both toFrankia inoculation and to N fertilizer. This positive interaction between P application and N treatment was reflected in wood volumes-inoculated trees and those trees supplied N fertilizer produced 34% and 95% more wood volume than did the uninoculated trees. These results demonstrate the potential to increase the productivity of Casuarina plantings by inoculation withFrankia and by alleviation of P deficiency.
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  • 31
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    Plant and soil 108 (1988), S. 151-162 
    ISSN: 1573-5036
    Keywords: combined nitrogen ; natural abundance ; 15N ; nitrogen fixation ; nitrogen response ; nodulation ; relative yield ; ureide analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Maize (Zea mays L.) and ricebean (Vigna umbellata [Thumb.] Ohwi and Ohashi) were grown in intercrop and monoculture on Tropaqualf soils under rainfed conditions in Northern Thailand yearly from 1983 to 1986. De Wit's replacement design was used to compare intercrops and monocultures with a constant plant density equivalent to 80 000 maize or 160 000 ricebean plants ha−1. Combined nitrogen was applied at varying levels to 200 kg N ha−1. In the final two seasons the intercrop ratio of maize: ricebean was also varied. At the time of maize maturity intercrops yielded upt 49 kg ha−1 more N in the above ground plant parts than the best monoculture. Dry matter, grain and nitrogen yield of maize and ricebean in intercrop relative to their monoculture yields (RY, relative yield) were significantly greater than their respective share of the plant population. Relative yield totals (RYT) for grain, dry matter and nitrogen were always greater than 1. Nitrogen uptake per maize plant increased with progressive replacement of maize by ricebean plants. This increase was similar to that obtained by applying combined N. Available soil nitrogen tended to decrease with increasing maize:ricebean ratio. Increasing the maize:ricebean ratio increased the % of nitrogen derived from fixation in ricebean, the increase being equivalent to that obtained by decreasing combined nitrogen application. Approximately the same amount of fertilizer and soil nitrogen was taken up by maize plus ricebean in intercrop as the maize monoculture. The results suggest that the improved nitrogen economy of the intercrop resulted from the strong competitiveness of maize in the use of mineral nitrogen and the enhancement of nitrogen fixation in intercropped ricebean which made it less dependent on the depleted pool of soil nitrogen.
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  • 32
    ISSN: 1573-5036
    Keywords: black gram ; boron deficiency ; borax rates ; green gram ; hollow heart ; hot-water-soluble boron ; kernel boron ; leaf boron ; peanut ; rice ; soybean ; sunflower ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effect of boron (B) on peanut and soybean was examined in two omission and one B fertilizer rate trial on a Typic Tropaqualf in Northern Thailand. The B rate trial was combined with a comparison of the response of sunflower, green gram, black gram, wheat, and rice in addition to peanut and soybean grown in irrigated rice-based cropping sequences over two years. Omitting B induced the hollow heart symptom in 10% of peanut kernels with the incidence of hollow hearts closely related to B concentration in the kernels. Omission of B had no effect on the appearance of soybean seed or on the grain yield of either soybean or peanut. In the B rate experiment, omitting B depressed grain yield by 50% in sunflower and by 40% to 80% in black gram, induced B deficiency symptoms in green gram and the hollow heart symptom in peanut kernels, but had not significant effect on the grain yield of soybean, peanuts, rice, or wheat. B deficiency apparently depressed grain yield in black and green gram by delaying or inhibiting reproductive development thus reducing pod set.
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  • 33
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    Plant and soil 106 (1988), S. 65-72 
    ISSN: 1573-5036
    Keywords: actinorhiza ; Alnus glutinosa ; Alnus incana ; fine sand ; Frankia ; nitrogen fixation ; nodulation ; nodulation capacity ; peat ; persistence ; pH ; spore ; survival
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Factors affecting the establishment of Alnus/Frankia symbioses were studied partly by following the survival ofFrankia strains exposed to different soil conditions, and partly by investigating the effect of pH on nodulation. TwoFrankia strains were used, both of the Sp− type (sporangia not formed in nodules). One of the strains sporulated heavily, while the other formed mainly hyphae. The strains originated fromAlnus incana root nodules growing in soils of pH 3.5 and 5.0. The optimum pH for their growth in pure culture was found to be 6.7 and 6.2, respectively. The strains were introduced into twoFrankia-free soils, peat and fine sand. Their survival, measured as the persistance of nodulation capacity using the plant infection technique, was followed for 14 months. The survival curves of the strains were similar despite the morphological differences between the strains in pure culture. The nodulation capacities declined over time both at 14 and 22°C. Survival was better in soils limed to a pH above 6 than in soils at their original pH (peat 2.9, fine sand 4.2). The effect of pH on nodule formation in Alnus seedlings by theFrankia strains was studied in liquid culture. The number of nodules increased linearly within the pH range studied (3.5–5.8). No nodules were formed at pH 3.5.
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  • 34
    ISSN: 1573-5036
    Keywords: Bradyrhizobium ; Glycine max ; nitrate ; nitrogen fixation ; nodule number ; soybean
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The capabilities of 36 diverse strains of bradyrhizobia to nodulate the soybean cv. Wilkin were determined in pots using starter-N levels of 0 and 51 mM (KNO3). At 21 days after planting, the strains showed a broad range of nodule number per plant. Nodulation was totally suppressed by N only in a group of strains which also formed relatively few nodules under N-free conditions. When plants were grown until 42 days, these strains continued to be poorly infective under N-free conditions, whereas their nodulation was greatly improved by the high-N treatment (N became limiting at between 21 and 42 days in the high-N treatment). We conclude that optimization of plant growth potential, by application of N, is important when determining strain infectivity.
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  • 35
    ISSN: 1573-5036
    Keywords: A-value ; isotope dilution ; nitrogen fixation ; quantification ; 15N
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In the estimation of the contribution of biological nitrogen fixation (BNF) to plant nutrition many authors have compared the estimates derived from the15N-isotope-dilution technique with those derived from the total N-difference technique. In this paper we show that agreement of these two estimates is mathematically inevitable when the recovery of labelled nitrogen (%FUE) by the “N2-fixing” (test) and control plants is equal, and that this agreement does not constitute an independent confirmation of the BNF estimate derived from one technique by the other. Even if different quantities of15N labelled fertilizer are added to the test and control crops (the A-value technique), but the % FUE for the two crops is the same, then again the BNF estimate derived from the A-value calculations will inevitably agree with the total N difference estimate.
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  • 36
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    Plant and soil 103 (1987), S. 123-125 
    ISSN: 1573-5036
    Keywords: Casuarina growth ; nodulation ; nitrogen fixation ; salinity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The growth, nodulation and nitrogen fixation ofCasuarina equisetifolia were compared at six levels (0–500mM NaCl) of salinity in sand culture. Dry weight of nodules, shoots and roots and N content of shoots increased at intermediate levels of salinity (50–100 mM) but decreased at 500 mM NaCl. Nodulation occurred at all NaCl levels, but at 500mM NaCl level, the nodule dry weight declined by 50% from the control. Increasing NaCl concentration of up to 200mM had little effect on the N2-fixation rate, but at 500mM NaCl level the rate decreased to 40% of the control value.
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  • 37
    ISSN: 1573-5036
    Keywords: ammonium ; Hippophaë rhamnoides ; hydroxyl-ion efflux ; ionic balance ; ion uptake ; nitrogen fixation ; nitrate ; nitrate reductase activity ; proton efflux ; rhizosphere pH
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Growth of 2-month-old nonnodulatedHippophaë rhamnoides seedlings supplied with combined N was compared with that of nodulated seedlings grown on zero N. Plant growth was significantly better with combined N than with N2 fixation and, although not statistically significant for individual harvests, tended to be highest in the presence of NH 4 + , a mixture of NH 4 + and NO 3 − producing the highest yields. Growth was severely reduced when solely dependent on N2 fixation and, unlike the combined-N plants, shoot to root ratios had only slightly increased after an initial decrease. An apparently insufficient nodule mass (nodule weight ratio 〈5 per cent) during the greater part of the experimental period is suggested as the main cause of the growth reduction in N2-fixing plants. Thein vivo nitrate reductase activity (NRA) of NO 3 − dependent plants was almost entirely located in the roots. However, when grown with a combination of NO 3 − and NH 4 + , root NRA was decreased by approximately 85 per cent.H. rhamnoides demonstrated in the mixed supply a strong preference for uptake of N as NH 4 + , NO 3 − contributing only for approximately 20 per cent to the total N assimilation. Specific rates of N acquisition and ion uptake were generally highest in NO 3 − +NH 4 + plants. The generation of organic anions per unit total plant dry weight was approximately 40 per cent less in the NH 4 + plants than in the NO 3 − plants. Measured extrusions of H+ or OH− (HCO 3 − ) were generally in good agreement with calculated values on the basis of plant composition, and the acidity generated with N2 fixation amounted to 0.45–0.55 meq H+. (mmol Norg)−1. Without acidity control and in the presence of NH 4 + , specific rates of ion uptake and carboxylate generation were strongly depressed and growth was reduced by 30–35 per cent. Growth of nonnodulatedH. rhamnoides plants ceased at the lower pH limit of 3.1–3.2 and deterioration set in; in the case of N2-fixing plants the nutrient solution pH stabilized at a value of 3.8–3.9 without any apparent adverse effects upon plant performance. The chemical composition of experimental and field-growing plants is being compared and some comments are made on the nitrogen supply characteristics of their natural sites.
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  • 38
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    Plant and soil 104 (1987), S. 113-120 
    ISSN: 1573-5036
    Keywords: actinorhizal plants ; Frankia ; Myrica gale ; nitrogen fixation ; root nodules ; spore-negative ; spore-positive
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The distribution of spore-positive and spore-negative root nodules ofMyrica gale L. was investigated at 34 sites throughout Maine. the sites represented a wide range of environmental conditions, including soils from organic to sand, soil pH from 3.1 to 6.4, elevations from 3 to 529 m, and average number of frost-free days per year from 80 to 162. Habitats included peatlands, streamsides and lakeshores. Spore(−) nodules dominated with 61% of the nodules examined sp(−) and 39% sp(+). Two sites were 100% sp(+), 7 sites were 100% sp(−) and the remaining 25 sites had varying proportions of both types. Overall, sp(+) and mixed sites dominated in the southern interior and coastal regions, areas with lower elevations and longer growing seasons. Spore(−) sites were located primarily in northern and western Maine, areas with higher elevations and shorter growing seasons. In all habitats occurrence of spore(+) modules was positively correlated with the average number of frost-free days per year (r=0.57 for peatlands, r=0.71 for lakeshores and streamsides). In addition, at the 21 lakeshore and streamside sites occurrence of sp(+) nodules was also positively correlated with percent organic matter in the soil (r=0.56) and negatively correlated with pH (r=−0.60). Within mixed sites sp(+) and sp(−) nodules were distribated randomly and were often closely intermingled.
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  • 39
    ISSN: 1573-5036
    Keywords: clover ; legume/grass mixture ; Lolium multiflorum ; Lolium perenne ; 15N ; nitrogen fixation ; nitrogen transfer ; Trifolium pratense ; Trifolium repens
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A field study was carried out near Zürich (Switzerland) to determine the yield of symbiotically fixed nitrogen (15N dilution) from white clover (Trifolium repens L.) grown with perennial ryegrass (Lolium perenne L) and from red clover (Trifolium pratense L.) grown with Italian ryegrass (Lolium multiflorum Lam.). A zero N fertilizer treatment was compared to a 30 kg N/ha per cut regime (90 to 150 kg ha−1 annually). The annual yield of clover N derived from symbiosis averaged 131 kg ha−1 (49 to 227 kg) without N fertilization and 83 kg ha−1 (21 to 173 kg) with 30 kg of fertilizer N ha−1 per cut in the seeding year. Values for the first production year were 308 kg ha−1 (268 to 373 kg) without N fertilization and 232 kg ha−1 (165 to 305 kg) with 30 kg fertilizer N ha−1 per cut. The variation between years was associated mainly with the proportion of clover in the mixtures. Apparent clover-to-grass transfer of fixed N contributed up to 52 kg N ha−1 per year (17 kg N ha−1 on average) to the N yield of the mixtures. Percentage N derived from symbiosis averaged 75% for white and 86% for red clover. These percentages were affected only slightly by supplemental nitrogen, but declined markedly during late summer for white clover. It is concluded that the annual yield of symbiotically fixed N from clover/grass mixtures can be very high, provided that the proportion of clover in the mixtures exceeds 50% of total dry mass yield.
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  • 40
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    Plant and soil 104 (1987), S. 175-181 
    ISSN: 1573-5036
    Keywords: rice ; soils ; submergence ; transformation ; zinc fractions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Distribution of different forms of Zn in 16 acid alluvial rice growing soils of West Bengal (India) and their transformation on submergence were studied. The results showed that more than 84% of total Zn occurred in the relatively inactive clay lattice-bound form while a smaller fractionviz. 1.1, 1.6, 11.1 and 2.0 per cent of the total occurred as water-soluble plus exchangeable, organic complexed, amorphous sesquioxide-bound and crystalline sesquioxide bound forms, respectively. All these four Zn forms showed significant negative correlations with soil pH (r=−0.48**, −0.39*, −0.61** and −0.67**, respectively), while the latter two Zn forms showed significant positive correlations with Fe2O3 (0.68** and 0.88***) and Al2O3 (0.89*** and 0.75***) content of the soils. The different Zn forms were found to have positive and significant correlations amongst each other, suggesting the existence of a dynamic equilibrium of these forms in soil. Submergence caused an increase in the amorphous sesquioxide-bound form of Zn and a decrease in each of the other three forms. The magnitude of such decreases in water-soluble plus exchangeable and crystalline sesquioxide-bound forms was found to be correlated negatively with initial pH values of the soils and positively with the increase in the amorphous sesquioxide-bound form, indicating their adsorption on the surface of the freshly formed hydrated oxides of Fe, which view was supported by the existence of significant positive correlation between the increase in the amorphous sesquioxide-bound form of Zn and that in AlCl3-extractable iron. The existence of a positive correlation between the decrease in crystalline sesquioxide-bound Zn and that in Fe2O3 content in soil suggested that on waterlogging the soil Zn occluded in the cry talline sesquioxide was released as a result of reduction of Fe2O3.
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  • 41
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    Plant and soil 105 (1988), S. 69-78 
    ISSN: 1573-5036
    Keywords: acetylene reduction ; Glycine max (L). ; nitrogen fixation ; nodule ; oxygen permeability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The low gas permeability of a diffusion barrier in the cortex of soybean nodules plays a significant role in the protection of nitrogenase from oxygen inactivation. It may also set an upper limit on nodule respiration and nitrogen fixation rates. Two methods which have been used to quantify the gas permeability of leguminous nodules are reviewed and found to be unreliable. A new assay technique for determining both the nodule activity and gas permeability is developed and tested. This ‘lag-phase’ assay is based on the time nodules require to reach steady-state ethylene production after being exposed to acetylene. The technique is rapid, insensitive to errors in biochemical parameters associated with nitrogenase, and is non-destructive. The method was tested with intact aeroponically grown soybean plants for which the mean nodule gas permeability was found to be 13.3×10−3 mms−1. This corresponds to a layer of cells approximately 35 um thick and is consistent with previously reported values.
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  • 42
    ISSN: 1573-5060
    Keywords: Oryza sativa ; rice ; O. perennis ; F1 weakness ; geographical distribution of gene ; Indica-Japonica
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Distribution of two complementary genes Hwc-1 and Hwc-2 causing F1 weakness was examined using 159 native rice cultivars and 30 strains of wild relatives collected from various sites of tropical Asia including the Himalayan foothills. Hwc-1 is carried by a Peruvian cultivar, Jamaica, a tester cultivar of this experiment. It was not found in the tested cultivars and strains. Hwc-2 was widely distributed in the Japonica types tested. No wild strains had either Hwc-1 or Hwc-2. Hwc-2 was infrequent in the Japonica types collected from Southern Asian countries. Hwc-2 was estimated to be indigenous to the Japonica types, may be linked with certain gene(s) related to adaptation.
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  • 43
    ISSN: 1573-5060
    Keywords: Oryza sativa ; rice ; Oryza glaberrima ; African rice ; interspecific hybrids ; hybrid sterility ; male sterility
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Several hybrids between Oryza sativa and O. glaberrima and their backcrosses with O. sativa were studied. Their seed sterility was very different; large differences were also observed in the level of pollen sterility and in the earliness of microspore failure. The proportion of aborted embryo sacs was much lower than the rate of sterile male gametophytes. The backcross populations were much more sterile than the corresponding F1 hybrids. On the base of our observations and according to the literature, we may conclude that genic unbalance is the main cause of sterility of these hybrids, but that physiological factors may also be involved. Thus a restoration of fertility is generally possible by selection. On the other hand, male-sterile lines could be bred from some of these hybrids.
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  • 44
    ISSN: 1573-5060
    Keywords: Oryza sativa ; rice ; floating habit ; genetics ; linkage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Deep water rice varieties in general have certain peculiar characters which are associated with floating habit. These characters are (i) early nodal differentiation, (ii) nodal rooting, (iii) spreading habit, (iv) awned grains, (v) brown hull colour, (vi) red pericarp (red rice), and (vii) seed dormancy. Inheritance of these characters and linkage relationship of genes governing these characters were studied in a cross between Pankaj (non floating) and Nageribao (floating) rice varieties. Nageribao, a cultivar from Assam possesses these characters. Early nodal differentiation was observed to be controlled by a single dominant gene, designated as ‘Nd’. Nodal rooting was controlled by two dominant complementary genes, designated as ‘Nr 1’ and ‘Nr 2’. We found an inhibitory factor for spreading habit and one for brown hull colour in Pankaj; the operation of two dominant duplicate genes ‘An 1’ and ‘An 2’ for controlling awning characters, a single dominant gene ‘Rd’ for red pericarp colour and a single dominant gene ‘Gd’ for grain dormancy. Joint segregations between these characters resulted in the assignment of genes in the X linkage group of indica rices with estimated map distances based on the cross-over values. The genes ‘An’ (awning), ‘Es’ (spreading habit), ‘Nr’ (nodal rooting) and ‘Nd’ (nodal differentiation) were observed to be associated with each other. The gene for red pericarp (Rd) was observed to be linked with the grain dormaney gene ‘Gd’.
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  • 45
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    Euphytica 34 (1985), S. 587-592 
    ISSN: 1573-5060
    Keywords: Oryza sativa ; rice ; Oryza glaberrima ; African rice ; cytoplasmic male sterility ; anther dehiscence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary To study differential nucleus-cytoplasm interactions between the two cultivated rice species, Oryza sativa and O. glaberrima, cytoplasmic substitution lines were made by using a glaberrima strain (G) and an Indica strain of sativa (S). The G cytoplasm had no adverse effect on pollen development when combined with the nucleus of S. On the other hand, when the S cytoplasm was combined with the G nucleus, the substitution line showed no seed set because of male sterility although the pollen grains were normally stained with I2-KI solution. A dominant gene derived from S strain seemed to cause anther indehiscence in the substitution line. Further, a restorer gene (Rf j)from Akebono of Japonica type was effective on pollen restoration in the male sterile line, suggesting that the S cytoplasm is the same as those of Japonica type in terms of a fertility-restoring system.
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  • 46
    ISSN: 1573-5036
    Keywords: acetylene reduction ; actinorhizal plants ; Alnus incana ; biomass production ; Frankia ; nitrogen fixation ; nodule type
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The efficiency of different FinnishFrankia strains as symbionts onAlnus incana (L.) Moench was evaluated in inoculation experiments by measuring nitrogen fixation and biomass production. Since all available pure cultures ofFrankia are of the Sp− type (sporangia not formed in nodules), but the dominant nodule endophyte ofA. incana in Finland is of the Sp+ type (sporangia formed in nodules), crushed nodules of thisFrankia type were included. The Sp− pure cultures, whether originating fromA. incana orA. glutinosa, produced with one exception, similar biomass withA. incana. The highest biomass was produced with an American reference strain fromA. viridis crispa. Using Sp+ nodule homogenates fromA. incana as inoculum, the biomass production was only one third of that produced by Sp− pure cultures from the same host. Hence, through selection of the endophyte it is possible to exert a considerable influence on the productivity ofAlnus incana.
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  • 47
    ISSN: 1573-5036
    Keywords: inoculation ; Medicago sativa ; nitrogen fixation ; nodulation ; Rhizobium meliloti ; Rhizobium trifolii ; Trifolium subterraneum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A method for estimating the nitrogen-fixing capacity of a population of rhizobia resident in soil is presented. legume test plants, growing under microbiologically-controlled conditions in test tubes packed with a vermiculite substrate moistened with a nitrogen-free plant nutrient solution, are inoculated directly with a suspension of the soil under examination. Rhizobia in the soil nodulate the test plants, and the amount of foliage dry matter produced in the 28 days after inoculation is regarded as an index of their effectiveness. An inoculum of at least 30, and preferably 100, rhizobia is needed to ensure that nitrogen fixation is not masked by delayed nodulation. The new method is tentatively described as the ‘whole-soil inoculation’ technique. Appraisals were made withTrifolium subterraneum L. andRhizobium trifolii and withMedicago sativa L. andR. meliloti. Soil-borne pathogens did not interfere with plant growth. The whole-soil inoculation technique was less tedious and time-consuming than an alternative method which involved extracting representative isolates from the soil and testing their effectiveness individually, and appeared to give more realistic values for the nitrogen-fixing capacity of the soil as a whole. Used in association with a field experiment, the whole-soil inoculation technique confirmed microbiologically that there had been an agronomic response to surface application of inoculant to poorly-nodulatedT. subterraneum pasture. It is submitted that this technique for determining the effectiveness of rhizobia in soil, combined with a plant-infection method for counting rhizobia, can be a reliable guide to the need for inoculation in the field.
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  • 48
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    Plant and soil 108 (1988), S. 191-199 
    ISSN: 1573-5036
    Keywords: nitrogen fixation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 49
    ISSN: 1573-5036
    Keywords: acetylene reduction ; nitrogen fixation ; organic substrates ; oxygen partial pressure ; Sorghum bicolor ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract To study the role or organic substrate availability as a factor limiting associative N2-fixation we measured acetylene reduction (AR) associated with roots of intact maize and sorghum plants before and after adding organic substrates to the nutrient solution in a hydroponic system. Chloramphenicol (Cam) or nalidixic acid (NA) was added along with the substrate to determine whether bacterial protein synthesis or cell replication was necessary to support increased AR following amendment. The grasses were grown in pots in a greenhouse or on a light bench for 4–6 weeks, and then brought into the laboratory to measure AR. Intact plants were separated from soil and transferred into plastic cylinders containing an N-free nutrient solution. The roots were isolated from the shoots by a silicone rubber seal and exposed to oxygen concentrations of 0–10 kPa. Rates of AR were measured before and after adding 0.01–0.10% (w/v) carbon as glucose, malate, succinate, ethanol, acetate, glutarate, propionate, or resorcinol. Only resorcinol and ethanol failed to substantially increase AR activity. Rates of AR increased by 1.5-to 2-fold within 2h and by 5-to 15-fold after 24h. Cam and NA prevented the stimulation of AR by glucose, but neither inhibitor caused AR associated with unamended plants to decrease. We conclude that the highly variable rates of AR that have been reported for associative symbioses, even under well-controlled conditions were governed to a large extent by the amount and type of organic substrates exuded by the roots. Proliferation of diazotrophs appeared to be necessary to increase root-associated AR activity but not to maintain a constant level of activity.
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  • 50
    ISSN: 1573-5036
    Keywords: antibiotic resistance ; Azospirillum inoculation ; establishment ofAzospirillum ; establishment ofHerbaspirillum ; Herbaspirillum inoculation ; rice ; sorghum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Two field experiments were carried out at the UAPNPBS experimental station, Seropédica, with two sorghum and one rice cultivars. The establishment, and inoculation effects, ofAzospirillum spp. andHerbaspirillum strains marked with antibiotic resistance were investigated. One grain sorghum (BR 300) and one sugar sorghum (Br 505) cultivar were used.Azospirillum lipoferum strain S82 (isolated from surface sterilized roots of sorghum) established in both cultivars and comprised 40 to 80% of theAzospirillum spp. population in roots and stems 60 days after plant emergence (DAE).Azospirillum amazonense strain AmS91 (isolated from surface-sterilized roots of sorghum) reached only 50%. At 90 DAE, S82 almost disappeared (less than 30% of establishment) while the establishment of AmS91 remained constant in roots and stems. No establishment ofH. seropedicae strain H25 (isolated from surface-sterilized roots of sorghum) orA. lipoferum strain S65 (isolated from the root surface of sorghum) could be observed on inoculated roots. Inoculation with S82, AmS91 or S65 but not withH. seropedicae H25, increased plant dry weight of both cultivars and total N in grain of the grain sorghum. In rice,A. lipoferum Al 121 andA. brasilense Sp 245 (isolated from surface sterilized rice and wheat roots respectively) established in the roots but there was no increase inAzospirillum spp. numbers due to inoculation. None of the strains affected plant growth or rice grain yield.Azospirillum amazonense, A82 andH. seropedicae Z95, which did not establish in roots, significantly enhanced seed germination.
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  • 51
    ISSN: 1573-5036
    Keywords: Azospirillum ; Cactaceae ; indoleacetic acid ; nitrogen fixation ; Opuntia ficus-indica ; Stenocereus pruinosus ; Stenocereus stellatus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Azospirillum isolates were obtained from rhizosphere soil and roots of three cactaceae species growing under arid conditions. All Azospirillum isolates from rhizosphere and roots ofStenocereus pruinosus andStenocereus stellatus were identified asA. brasilense; isolates of surface-sterilized roots fromOpuntia ficus-indica were bothA. brasilense andA. lipoferum. Azospirilla per g of fresh root in the three species ranged from 70×103 to 11×103. The most active strains in terms of C2H2 reduction (25–49.6 nmol/h·ml) and indoleacetic acid (IAA) production (36.5–77 μg/ml) were those identified asA. brasilense and isolated from Stenocereus roots.A. lipoferum isolated from Opuntia roots produced low amounts of IAA (6.5–17.5 μg/ml) and low C2H2-reduction activity (17.8–21.2 nmol/h·ml).
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  • 52
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    Plant and soil 106 (1988), S. 135-141 
    ISSN: 1573-5036
    Keywords: flooding ; organic matter ; rice ; sodic soil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The influence of organic matter, added in the form ofCasuarina equisetifolia andAcacia nilotica leaves, on the chemical and electrochemical kinetics of a flooded sodic soil and rice growth, was studied in a pot experiment. With the addition of organic matter, not only the peaks of CO2 production and maximum concentrations of extractable Fe and Mn and other cations occurred earlier, but their concentrations were also significantly higher as compared to the control (no organic matter). The high concentrations of CO2 and reduced redox potential (Eh) appeared to influence the soil pH, exchangeable sodium percentage (ESP) and the accumulation of cations and to be chiefly responsible for better rice growth. Acacia proved more effective than Casuarina in improving rice yield and the sodic soil.
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  • 53
    ISSN: 1573-5036
    Keywords: organic matter ; rice ; submergence ; transformation ; zinc fraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Laboratory and greenhouse experiments were conducted with two soilsviz., laterite and alluvial to study the transformation of applied Zn in soil fractions under submerged condition in the presence and absence of added organic matter and its relationship with Zn nutrition of rice plants. The results showed that application of organic matter caused a decrease in the concentration of Zn in shoot and root of rice plants and helped in translocating the element from root to shoot. The per cent utilization of applied Zn by plants was also found to increase by the application of organic matter. The transformation of applied Zn in different fractions in soils showed that a major portion (53.6–72.6%) of it found its way to mineral fractions leaving only 1.0–3.3, 6.6–18.9, 11.0–21.6 and 2.3–8.8% of the applied amounts in water soluble plus exchangeable, organic complexed, amorphous sesquioxides and crystalline sesquioxides bound fractions respectively. Application of organic matter favoured such transformation of applied Zn into these fractions except the mineral and crystalline sesquioxides bound ones. Simple correlation and multiple regression analyses between applied Zn in different soil fractions and fertilizer Zn content in plants showed that organic matter application increased the predictability of fertilizer Zn content in plants which has been attributed to the higher per cent recovery of applied Zn in plant available fractions in soils in presence of added organic matter.
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  • 54
    ISSN: 1573-5036
    Keywords: Azospirillum lipoferum ; nitrogen fixation ; nodules ; peanut cultivars ; Rhizobium ; yield
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Peanut (Arachis hypogaea Linn.) Cvs. Robut 33-1 and JL 24 were inoculated with Rhizobium strain NC 92 and a strain ofAzospirillum lipoferum singly and as mixed inoculum. Seed inoculation with these bacteria enhanced nodulation, N content and yield of these cultivars under field conditions. While a mix inoculation of these two diazotrophic cultures had an adverse effect on these parameters as compare to single inoculation.
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  • 55
    ISSN: 1573-5036
    Keywords: 15N ; nitrogen fixation ; plant breeding ; Vicia faba
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Before starting a breeding program aimed at improving the nitrogen nutrition ofVicia faba, the authors tried an alternative technique to the acetylene reduction assay, to measure some genetic variability in the plant material. The quantity of dinitrogen fixed by several cultivars ofVicia faba was estimated using a low enrichment15N tracer method and high precision15N mass spectrometry. The fababeans were cultivated for two years in two different soils. The percentage of fixed dinitrogen in the seed varied between genotypes from 40 to 83% of the total nitrogen and was positively correlated with the total seed nitrogen (r=0.64 to 0.86). A highly significant positive correlation was also found between the total seed nitrogen and the quantity of fixed dinitrogen in the seed (r=0.95 to 0.99). The technique used to measure dinitrogen fixation proved to be useful and reliable enough to discriminate between various genotypes, grown over a period of two years in two different soils. However, several non-fixing control plants showed significant differences in their15N enrichment and the problem of choosing a good reference plant was raised and discussed.
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  • 56
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    Plant and soil 101 (1987), S. 29-37 
    ISSN: 1573-5036
    Keywords: assimilate partitioning ; growth analysis ; leaf area ; nitrate ; nitrogen fixation ; 15N isotope dilution ; pea ; Pisum sativum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The seasonal patterns of growth and symbiotic N2 fixation under field conditions were studied by growth analysis and use of15N-labelled fertilizer in a determinate pea cultivar (Pisum sativum L.) grown for harvest at the dry seed stage. The patterns of fertilizer N-uptake were almost identical in pea and barley (the non-fixing reference crop), but more fertilizer-N was recovered in barley than in pea. The estimated rate of N2 fixation in pea gradually increased during the pre-flowering and flowering growth stages and reached a maximum of 10 kg N fixed per ha per day nine to ten weeks after seedling emergence. This was the time of early pod-development (flat pod growth stage) and also the time for maximum crop growth rate and maximum green leaf area index. A steep drop in N2 fixation rate occurred during the following week. This drop was simultaneous with lodging of the crop, pod-filling (round pod growth stage) and the initiation of mobilization of nitrogen from vegetative organs. The application of fertilizer-N inhibited the rate of N2 fixation only during that period of growth, when the main part of fertilizer-N was taken up and shortly after. Total accumulation of fixed nitrogen was estimated to be 244, 238 and 213 kg N ha−1 in pea supplied with nil, 25 or 50 kg NO 3 − −N ha−1, respectively. About one-fourth of total N2 fixation was carried out during preflowering, one fourth during the two weeks of flowering and the remainder during post-flowering. About 55% of the amount of N present in pods at maturity was estimated to be derived from mobilization of N from vegetative organs. “Starter” N (25 or 50 kg NO 3 − −N ha−1) did not significantly influence either dry matter and nitrogen accumulation or the development of leaf area. Neither root length and root biomass determined 8 weeks after seedling emergence nor the yield of seed dry matter and nitrogen at maturity were influenced by fertilizer application.
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  • 57
    ISSN: 1573-5036
    Keywords: 15N ; Cajanus cajan ; intercropping ; isotope dilution ; nitrogen fixation ; nitrogen transfer ; residual effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Two experiments were carried out from 1981 to 1983 in Vertisol field at ICRISAT Center, Patancheru, India to measure N2-fixation of pigeonpea [Cajanus cajan (L.) Millsp.] using the15N isotope dilution technique. One experiment examined the effect of control of a nodule-eating insect on fixation while another in vestigated the effect of intercroping with cereals on fixation and the residual effect of pigeonpea on a succeeding cereal crop. Although both experiments indicated that at least 88% of the N in pigeonpea was fixed from the atmosphere, one result is considered fortuitous in view of the differential rates of growth of the legume and the control, sorghum [Sorghum bicolor (L.) Moench]. The difference method of calculation in dieated negative fixation and the results emphasized the problem of finding a suitable nonfixing control. In a second experiment, when all plants were confined to a known volume of soil to which15N fertilizer was added in the field, these problems were overcome, and isotope dilution and difference methods gave similar results of N2-fixation of about 90%. In intercropped pigeonpea 96% of the total N was derived from the atmosphere. This estimate might be an artifact. There was no evidence of benefit from N fixed by pigeonpea to intercropped sorghum plants. Plant tissue15N enrichments of cereal crops grown after pigeonpea indicated that the cereal derived some N fixed by the previous pigeonpea. Thus residual benefits to cereals are not only an effect of ‘sparing’ of soil N.
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  • 58
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    Plant and soil 102 (1987), S. 49-54 
    ISSN: 1573-5036
    Keywords: Azolla pinnata ; Azolla dual cropping ; N ; P uptake ; rice ; soil fertility
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Azolla and urea application in a rice field transplanted with square (20 cm×20 cm) and rectangular (10 cm×40 cm) spacings for three consecutive seasons were found to increase significantly uptake of N and P by the rice plants, irrespective of seasons. Azolla treatments increased the organic C content of the soil during both wet and dry seasons, while its N and P contents were more only during the wet seasons. Urea did not affect N, P and organic C contents of the soil. Spacing had no significant effect on N and P uptake by the rice plant or N, P and C contents of the soil. Maximum N and P uptake in rice were obtained by growing two crops of Azolla after transplanting in addition to its incorporation before transplanting. This treatment showed significantly more N uptake than the urea at 60 kg N ha−1 during wet and dry seasons of 1982. Among Azolla treatments, twice Azolla dual cropping although showed comparatively lower uptake of N and P, it was comparable to that of 60 kg N ha−1 urea.
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  • 59
    ISSN: 1573-5036
    Keywords: corn ; cropping pattern ; inoculum potential ; mungbean ; rice ; VAM fungi
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The numbers of infectious propagules of indigenous vesicular-arbuscular mycorrhizal (VAM) fungi were determined at different stages of the rice-based cropping systems in two irrigated rice fields of varying strata and in a rainfed field. The most-probable-number method was used to estimate the infective VAM fungal population. On the irrigated farms the mycorrhizal inoculum was consistently less in the poorly drained low-lying field with a rice-rice cropping pattern than in the field in the better-drained upper stratum with a rice-corn-mung-bean pattern. The population of infective VAM fungi was generally low after the wet season rice crop when the field was inundated for a long period, increased during fallow in the presence of weeds, and was highest upon the maturity of the dry-season corn or rice crop. In the rainfed area the highest endophytic population was found at maturity of the mungbean crop and the lowest after land preparation prior to rice seeding.
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  • 60
    ISSN: 1573-5036
    Keywords: leaf elongation rate ; leaf water potential ; maize ; nitrogen ; nutrient uptake ; phosphorus ; potassium ; rice ; soybean ; transpiration rate ; water stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A pot experiment was conducted in the greenhouse to determine and compare the responses of rice (Oryza sativa L. var, IR 36), maize (Zea mays L. var. DMR-2), and soybean (Glycine max [L.] Merr. var. Clark 63) to soil water stress. Leaf elongation, dawn leaf water potential, transpiration rate, and nutrient uptake in stressed rice declined earlier than in maize and soybean. Maize and soybean, compared with rice, maintained high dawn leaf water potential for a longer period of water stress before leaf water potential. Nutrient uptake under water stress conditions was influenced more by the capacity of the roots to absorb nutrients than by transpiration. Transport of nutrients to the shoots may occur even at reduced transpiration rate It is concluded that the ability of maize and soybean to grow better than rice under water stress conditions may be due to their ability to maintain turgor as a result of the slow decline in leaf water potential brought about by low, transpiration rate and continued uptake of nutrient, especially K, which must have allowed osmotic adjustment to occur.
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  • 61
    ISSN: 1573-5036
    Keywords: calcium deficiency ; Na/Ca ratio ; Na/K ratio ; rice ; saline culture solution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Two experiments were conducted in saline culture solution to find out the causes of rolling and bleaching of young leaves of rice, observed previously in experiments on coastal saline-sodic soil. Symptoms similar to those methioned above were observed on young leaves of cv. KS282 in saline culture solution with Na/Ca ratios of 100 or greater. These symptoms were due to Ca deficiency but not of Cu, since Cu concentration was higher in saline shoots than in the control. The decreasing Na/K or Na/Ca ratio in the saline solution decreased Na and Cl concentration in the shoot. In addition to salinity, Na/Ca and Na/K ratios of the growth medium significantly influenced the shoot and root growth of rice.
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  • 62
    ISSN: 1573-5036
    Keywords: bean ; sand-alumina ; nitrogen fixation ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The efficacy of the alumina system for differentiating between bean (Phaseolus vulgaris L.) genotypes for growth at different levels of phosphorus availability was determinated. In addition to response to P levels, comparisons were made between plants receiving N either from fertilizer or nitrogen fixation. When the cv. Carioca was provided with either 100 ppm of N or inoculated withRhizobium leguminosarum biovarphaseoli, differences in shoot dry weight and nodule number were related to P level. There was a greater proportion of green, ineffectivevs. red, active nodules at the low P concentration than at the higher P concentration. In a second experiment, two cvs., Puebla 152 and Carioca and the breeding line UW 24-21, either were inoculated with rhizobia or provided with 150ppm of N. Each genotype-nitrogen combination was grown at 8 levels of P. There was a positive effect of P level on shoot dry weight, nodule number and nodule mass. Root mass was affected less than nodule or shoot mass by the P level of the growth medium. Nodule mass, but not P concentration in the nodules, was affected by P level, whereas in the other plant tissues, P concentrations were lower at lower P levels in the media.
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  • 63
    ISSN: 1573-5036
    Keywords: floodwater ; nitrogen ; phosphorus ; potassium ; oxygen ; rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Concentrations of N, P and K were measured in floodwater and in floating rice cultivars growing at up to 2m water depths in the central flood plain of Thailand. Concentrations of N, P and K in floodwater were often higher than those reported for oligotrophic lakes, nevertheless the floodwater contained 4–45 times less K and 15–90 times less N than concentrations reported in most soil solutions. P concentrations were similar in the floodwater and in most soil solutions. Concentrations of nutrients in leaves indicated there may be deficiencies of P at two sites and a deficiency of N at one of two sites. Data are discussed in terms of reduced nutrient uptake in rice fields at low O2 concentrations which have recently been measured in these areas.
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  • 64
    ISSN: 1573-5036
    Keywords: inoculation method ; nitrogen fixation ; reclamation ; Rhizobium ; sericea lespedeza ; surface mining
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A field study was conducted on freshly reclaimed surface-mined area to determine response of sericea lespedeza (Lespedeza cuneata [Dumont] G. Don.) to delayed rhizobial inoculation. Soybeans (Glycine max L.) were used as a control legume. Plots were inoculated with spray applications of rhizobial suspensions at seeding, cotyledon stage or second trifoliate leaf stage, or not inoculated. Starter N at 0, 10 or 20 kg ha−1 was applied preplant in a factorial arrangement with inoculation timings.G. max. was grown for 92 days andL. cuneata for 121 days. Starter N increased plant growth and total shoot N in both species. However, % shoot N was found to increase only inL. cuneata. Delaying inoculation had no significant effect upon total shoot N or % shoot N accumulation inL. cuneata. Inoculation ofG. max at planting produced greater plant growth and N accumulation than delayed inoculation treatments. Application of inoculum as a surface spray appeared to be an effective method for delayed inoculation as evidenced by nodule formation. Lack of increased plant growth, regardless of time of inoculation, suggests that delayed inoculation does not improve establishment and growth ofL. cuneata in minesoil.
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  • 65
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    Plant and soil 109 (1988), S. 227-234 
    ISSN: 1573-5036
    Keywords: acetylene reduction ; diurnal cycles ; nitrogen fixation ; oxygen permeability ; photosynthesis ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract While diurnal cycles in nitrogen fixation rates are sometimes assumed to result from diurnal variation in photosynthetically active radiation, contradicting evidence exists that indicate soil temperature is the primary environmental influence. These studies assessed the significance of temperature on soybean nitrogen fixation under field conditions. Two groups of intact field-grown soybean plants, one at ambient and the other exposed to a 10°C diurnal variation in soil temperature, were nondestructively assayed for acetylene reduction rates. Activity was closely associated with soil temperature (R2=0.85), even when temperature was 12 h out of phase with ambient. Data were also obtained to determine if the effects of rhizosphere temperature on nitrogen fixation are mediated through an effect on the nodule oxygen permeability. Nodule oxygen permeability of intact, aeroponically grown soybean was closely correlated with the diurnal changes in temperature (R2=0.90).
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  • 66
    ISSN: 1573-5036
    Keywords: Glycine max ; isotope dilution method ; 15N ; nitrogen ; nitrogen fixation ; Rhizobium soybean
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Nine strains ofRhizobium japonicum (Bradyrhizobium japonicum) were screened for nitrogen fixation in combination with two cultivars of soybean, Chippewa and Dunadja at two levels of nitrogen fertilization,i.e. 20 kg N ha−1 and 100 kg N ha−1 using15N isotope dilution method. Plant dry weight, nitrogen yield, percent N derived from atmosphere (% Ndfa) and total amount of N2 fixed were strongly influenced by the specific combination of host-genotype and rhizobial strain. The interaction between the host and microsymbiont were so specific that accurate prediction of symbiotic performance of either partner in relation to a particular host or strain of Rhizobium appears impossible. The sensitivity of nitrogen fixation to combined nitrogen was furthermore dependent upon both the rhizobial strain and host-Rhizobium association. It is therefore, inadvisable to describe a certain bacterium as being fully effective/ineffective or sensitive/tolerant to combined nitrogen, except in relation to a particular host-genotype. There is scope for obtaining promising host-Rhizobium associations tolerant to combined nitrogen through exploiting the interactive effects between the host-genotypes and strains of Rhizobium.
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  • 67
    ISSN: 1573-5036
    Keywords: acetylene reduction ; actinorhizae ; Alnus clones ; combined N ; Frankia strains ; nitrogen fixation ; root nodules ; symbiosis performance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The addition of combined nitrogen to substrate at an appropriate rate can stimulate N2-fixation thus inreasing the efficiency of the Alnus-Frankia symbiosis. To examine how nitrogen additions can effect the peformance of different pairs of symbionts, growth and time course of N2-fixation were studied in plants supplied with NH4NO3. Two cloned ofAlnus glutinosa (L.) Gaertn., propagatedin vitro, were inoculated with two strains ofFrankia (AVP3d and ACN14a) and grown in a greenhouse. Calcined montmorillonite (TotfaiceR) was used as growth substrate. Six N treatments were made up of varied amounts of NH4NO3 supplied in one single addition shortly before inoculation. Weekly measurements of shoot height and repeated measurements of nitrogenase activity (acetylene reduction) performed on intact root systems were used to monitor the development of the symbioses. Nitrogen treatments containing from 0.10 to 0.68 mg N g−1 dry substrate stimulated N2-fixation as well as growth. The relative performance of the two clones was different according to N treatment; one clone showed a greater benefit from the nitrogen input. Our results support the recommendation that selection of symbionts according to performance should be carried out with an input of combined nitrogen. This can provide optimum conditions for the development of each pair of symbionts.
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  • 68
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    Plant and soil 104 (1987), S. 103-111 
    ISSN: 1573-5036
    Keywords: actinorhizal plants ; Alnus incana ssp.rugosa ; Frankia ; nitrogen fixation ; root nodules ; spore-negative ; spore-positive
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The distribution of spore-positive (sp+) and spore-negative (sp−) root nodules ofAlnus incana ssp.rugosa (DuRoi) Clausen (speckled alder) was examined at 29 sites with a wide range of environmental conditions in Maine, USA. These included: pH 3.4 to 7.0, soil texture ranging from coarse gravel to clay to organic soils, elevation from 3 to 591 m and latitude 43 to 47°N. Habitat types included disturbed areas, streamsides, swamps and old fields. Sp (−) nodules were substantially more common, making up 76% of all nodules, whereas only 24% were sp (+). Sp (−) nodules often occurred in pure stands and predominated at disturbed sites with mineral soils at the surface and in old fields and swamps with pH〉4.0 Sp (+) nodules were nearly always found in mixture with sp (−) nodules. They occurred primarily at streamside and lakeshore sites where they made up 40% of the nodules and at sites with pH〈4.0 regardless of habitat type. It is suggested that sp (−) strains ofFrankia may be maintained at a site by saprophytic growth in soil and thus nodulate newly established hosts, whereas sp (+) strains may be maintained primarily by spore production within nodules and thus depend on extended presence of the host.
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  • 69
    ISSN: 1573-5060
    Keywords: Orvza sativa L. ; rice ; drought tolerance ; genetics ; leaf water potential ; root pulling resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Avoidance of drought stress is commonly associated with root system characteristics and root development. The inheritance of root pulling resistance in rice (Oryza sativa L.) was investigated and its relationship with visual field scores for drought tolerance was studied. Transgressive segregation for high root pulling resistance was observed in 3 crosses (high x high, low x high, and intermediate x intermediate). Both dominant and additive genes control the variation. F1 superiority for high root pulling resistance was observed and could be exploited in an F1 hybrid breeding program. F2 distribution curves indicated that plants highly resistant to root pulling can be obtained not only from low x high and high x high crosses, but also from intermediate x intermediate crosses. Root pulling resistance in rice has a low heritability (39 to 47%). Thus, breeding for a high root pulling resistance may best be accomplished by selection based on line means rather than individual plant selection. Field screening showed significant differences in leaf water potential among random F3 lines. F3 lines with higher leaf water potential had better visual scores for drought tolerance. Visual drought tolerance scores were correlated with root pulling resistance. Plants with high root pulling resistance had the ability to maintain higher leaf water potentials under severe drought stress. The usefulness of the root pulling technique in selecting drought tolerant genotypes was confirmed.
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  • 70
    ISSN: 1573-5060
    Keywords: Vicia faba ; fababean ; Rhizobium ; genetics ; plant mutant ; nitrogen fixation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A symbiotically defective mutant in Vicia faba is described. This character is controlled by a recessive gene named sym-1. Reciprocal graft experiments indicate that only the root system controls its expression. Depending on the strain of Rhizobium, the root phenotype can be either Fix+ Nod- or Nod-.
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  • 71
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    Euphytica 38 (1988), S. 261-269 
    ISSN: 1573-5060
    Keywords: Oryza sativa ; rice ; amylose content ; single grain analysis ; cooking characteristics ; dosage effects ; dull endosperm ; translucent endosperm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The inheritance of low and very low amylose contents in six rice crosses and their reciprocals was studied by single grain analysis of parents F1, F2, B1 and B2 seeds. To minimize the environmental effects, the seeds of all generations of all crosses were produced in a single season. The results indicated different dosage effects in different crosses. One major gene was found to govern a difference of 6–12% in amylose content in low and intermediate amylose parents. Very low amylose content was similarly found to be governed by one major gene in crosses between very low- and low-amylose content parents. Minor genes and modifiers also seem to play some role. In the cross between two low amylose parents differing by about 2.5% in amylose content, the differences appeared to be controlled by some minor genes and modifiers. The selection program in different crosses has been suggested.
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  • 72
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    Euphytica 40 (1989), S. 97-102 
    ISSN: 1573-5060
    Keywords: Oryza sativa ; rice ; ratooning ability ; genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Genetic analysis of generation means of F1, F2, F3, F4, and the parental populations of the cross IR10154-23-3-3A/IR15795-232-3-3-2 for ratooning ability was conducted. Good ratooning ability is a recessive trait. The parents differed by at least two pairs of major genes for ratooning ability. A large proportion of transgressive segregants in F2 suggested that the expression of ratooning ability is influenced not only by major genes but also by modifiers. Broad-sense heritability estimates computed by different methods ranged from 0.66 to 0.88. Narrow-sense heritability by the F4–F3 regression method was 0.39. The heritability estimates were 0.42 and 0.33 by the variance component method. The prevalence of additive x additive type of gene effects along with prominent additive effects imply some scope for selection in the segregating generations. However, non-additive type of gene action also affects the expression of ratooning ability.
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  • 73
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    Euphytica 42 (1989), S. 35-40 
    ISSN: 1573-5060
    Keywords: Oryza sativa ; rice ; epistasis ; additive ; dominance ; genetic system ; homozygote x heterozygote ; heterozygore x heterozygote
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The triple test cross analysis in rice brought out that significant epistasis is present for most of the characters in the three crosses except for 100 grain weight in two crosses (Co 39 × Co 41) and (Co 39 × Co 40) and plant height in one cross (Co 39 × IR 20). Epistasis of ‘i’ (homozygote × heterozygote) and ‘l’ (heterozygote × heterozygote) interactions are also detected in all the three crosses. The D component was significant for all the traits in the three crosses and H was significant in cross Co 39 × Co 41 for all characters. For tiller number in cross Co 39 × IR 20 and for tiller number and 100 grain weight in cross Co 39 × Co 40, the H component was not significant. In all the crosses D component was higher than H.
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  • 74
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    Euphytica 42 (1989), S. 265-268 
    ISSN: 1573-5060
    Keywords: Oryza sativa ; rice ; photosynthesis ; grain yield ; genotype ; isozyme ; esterase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Four Indica and one Japonica (Tainung 67) of rice (Oryza sativa L.) varieties had an esterase band (tentatively designated as E1), and also had higher photosynthetic ability than other five Japonica varieties without E1 band. The F1 plants of Tainung 67 × Mineyutaka (low photosynthetic ability, no E1 band) showed E1 band and a low photosynthetic ability. Of 34 F2 plants, 28 had E1 band, but 6 had no E1 band of which 5 plants showed a low photosynthetic ability. These results suggest that an esterase gene and one of the photosynthesis gene are linked, and the gene for low photosynthetic ability is dominant. Among 42 new Japonica strains and 2 control varieties bred in Taiwan, most genotypes with E1 band showed higher grain yield potential (grain field/growth days) in local test. Esterase band may be used as a marker for high photosynthesis and grain yield ability in breeding.
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  • 75
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    Euphytica 43 (1989), S. 47-51 
    ISSN: 1573-5060
    Keywords: Oryza sativa ; rice ; protein content ; protein quality ; amino acid concentration ; nutritive value ; animal growth test
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Three breeding lines (F8) of rice, derived from cross between Brimful X Koshihikari were tested for protein, amino acid, growth test with rats and yield parameters in field trials. The breeding lines had higher protein and amino acid concentrations than the leading Japanese cultivar Koshihikari, which was grown as a control. Grain yield in the breeding lines was lower than that of Koshihikari (4.5 t/ha). The grain-protein yield of the breeding lines was higher (500 kg/ha) than that of Koshihikari (440 kg/ha). The average gain in weight of rats fed brown and milled rices of the breeding line was 19 and 21 g, respectively: in control rats fed Koshihikari average gain was −1 and 8 g. These results showed that the breeding lines of rice can be developed which possess higher food value than the available varieties.
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  • 76
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    Plant and soil 109 (1988), S. 207-213 
    ISSN: 1573-5036
    Keywords: Ceanothus ; chaparral ; nitrogen fixation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Nitrogen fixation in excised root nodules of 2-year-old, postfireCeanothus tomentosus andC. leucodermis seedlings was measured over an 8-month period using the acetylene reduction method. High levels of NO3−N and NH4−N present in postfire soils were limited to the upper 10 cm and did not inhibit nodulation in these deeper-rooting seedlings. Decreases in acetylene reduction activity occurred with decreased soil moisture and increased soil temperature. Nitrogen gains from these two Ceanothus shrub seedlings totalled 1.6 kg N ha−1 yr−1.
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  • 77
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    Plant and soil 110 (1988), S. 225-238 
    ISSN: 1573-5036
    Keywords: amino acids ; Azospirillum brasilense ; A. lipoferum ; A. amazonense ; A. halopraeferens ; growth regulation ; nitrogen fixation ; osmotolerance ; siderophores
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The nitrogenase activity ofAzospirillum spp. is efficiently regulated by environmental factors. InA. brasilense andA. lipoferum a rapid ‘switch off’ of nitrogenase activity occurs after the addition of ammonium chloride. As in photosynthetic bacteria, a covalent modification of nitrogenase reductase (Fe-protein) is involved. InA. amazonense, a non-covalent mechanism causes only a partial inhibition of nitrogenase activity after ammonium chloride is added. In anaerobic conditions, nitrogenase reductase is also ‘switched off’ by a covalent modification inA. brasilense andA. lipoferum. Short-time exposure ofAzospirillum to increased oxygen levels causes a partially reversible inhibition of nitrogenase activity, but no covalent modification is involved.Azospirillum spp. show variations in their oxygen tolerance. High levels of carotenoids confer a slightly improved oxygen tolerance. Certain amino acids (e. g. glutamate, aspartate, histidine and serine) affect growth and nitrogen fixation differently inAzospirillum spp. Amino acids may influence growth and nitrogen fixation ofAzospirillum in the association with plants.Azospirillum brasilense andA. halopraeferens are the more osmotolerant species. They utilize most amino acids poorly and accumulate glycine betaine, which also occurs in osmotically stressed grasses as a compatible solute to counteract osmotic stress. Nitrogen fixation is stimulated by glycine betaine and choline. Efficient iron acquisition is a prerequisite for competitive and aerotoleran growth and for high nitrogenase activity.Azospirillum halopraeferens andA. amazonense assimilate iron reasonably well, whereas growth of someA. brasilense andA. lipoferum strains is severely inhibited by iron limitation and by competition with foreign microbial iron chelators. However, growth of certain iron-limitedA. brasilense strains is stimulated by the phytosiderophore mugineic acid. Thus, various plant-derived substances may stimulate growth and nitrogen fixation ofAzospirillum.
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  • 78
    ISSN: 1573-5036
    Keywords: acid soils ; aluminium in soils ; aluminium toxicity ; exchangeable aluminium ; New Zealand ; nitrogen fixation ; soil acidity ; Trifolium repens ; white clover
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of soil acidity on the growth and N2-fixing activity of white clover in seven acid topsoils and subsoils of New Zealand were investigated using a glasshouse experiment. The application of phosphate (Ca(H2PO4)2) to the soils resulted in very large increases in white clover growth on all soils. The application of phosphate, as well as increasing P supply, also decreased 0.02M CaCl2-extractable Al levels, but had little effect on exchangeable Al levels. Where adequate phosphate was applied, increasing rates of lime (CaCO3) resulted in increased plant growth on most soils. N2[C2H2]-fixing activity was increased by the first level of lime for one soil, but generally remained approximately constant or declined slightly at higher rates of lime. Up to the point of maximum yield, white clover top weight was more highly correlated with 0.02M CaCl2-extractable soil Al than with exchangeable Al or pH. At pH values greater than 5.5, plant yield declined on some soils, apparently because of Zn deficiency. The data suggest that white clover is unlikely to be affected by Al toxicity at 0.02M CaCl2-extractable Al levels of less than about 3.3 μg g−1. However, there were differences between soils in apparent plant tolerance to 0.02M CaCl2-extractable Al, which appeared to be caused by differing C levels in the 0.02M CaCl2 extracts.
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  • 79
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    Plant and soil 112 (1988), S. 247-254 
    ISSN: 1573-5036
    Keywords: isotope dilution ; 15N ; nitrogen ; nitrogen fixation ; nitrogen transfer ; ryegrass ; white clover
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The stable isotope15N is particularly valuable in the field for measuring N fixation by isotope dilution. At the same time other soil-plant processes can be studied, including15N recovery, and nitrogen transfer between clover and grass. Three contrasting sites and soils were used in the present work: a lowland soil, an upland soil, and an upland peat. Nitrogen fixation varied from 12 gm−2 on lowland soil to 2.7 gm−2 on upland peat. Most N transfer occurred on upland soil (4.2 gm−2) which, added to nitrogen fixed, made a total of 8.7 gm2 input during summer 1985.15N recovery for the whole experiment was small, around 25%. Measurement of dead and dying leaves, stubble and roots, suggests that plant organ death is the first stage in N transfer from white clover to ryegrass, through the decomposer cycle. Decomposition was fastest on lowland soils, slowest on peat. On lowland soil this decomposer nitrogen is apparently subverted before transfer, probably by soil microbes. Variations in natural abundance of15N in plants were found in the two species on the different soils. These might be used to measure nitrogen fixation without adding isotope, but the need for many replicates and repeat samples would limit throughput.
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  • 80
    ISSN: 1573-5036
    Keywords: dual symbiosis ; nitrogen fixation ; ricebean ; seed legume
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Ricebean (Vigna umbellata (Thumb) Ohwi and Ohashi, cv. RBL-1) was inoculated withGlomus fasciculatum andRhizobium leguminosarum and grown on a sterilized sandy loam soil, deficient in plant avalable P. Dual inoculation caused a significantly greater increase in VAM colonization, N and P content of the host plant, nodulation, growth and yield of ricebean as compared to the inoculation with either of the endosynbiont. Response of ricebean to dual inoculation supported the phenomena of synergistic interaction and tripartite association between the Host-VAM fungus-Rhizobium system.
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  • 81
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    Plant and soil 114 (1989), S. 147-157 
    ISSN: 1573-5036
    Keywords: copper ; DTPA ; flooded ; iron ; manganese ; redox ; rice ; soil catena ; waterlogged ; zinc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Soil samples from surface and sub-surface horizons in the well-drained and poorly-drained members of three soil catenas were incubated under submergence or at field capacity to study the effects of these incubation conditions and prior natural drainage on the solubility of four plant micro-nutrients. Iron, Mn, Zn and Cu were extracted by water using a 1∶1 water:soil ratio. The four micronutrient metals were also extracted by DTPA solutions buffered at either pH 5.3 or pH 7.3 to compare the effectiveness of these two extractants under these incubation conditions with acid soils. Generally the extractability of the nutrients was much affected by the horizon (A, E or B) with A horizons having the greatest amounts of all nutrients and undergoing greater changes in water- and DTPA-extractability during incubation. Soil drainage class (wellvs. poorly drained) had few effects. Incubation moisture regime had major effects on water extractable Fe and Mn with lesser effects on Zn and Cu. Submerged soils generally had the greatest levels of water extractable nutrients, though rice uptake did not reflect this. DTPA at pH 5.3 extracted 2 to 3 times as much Fe, Mn, Zn and Cu as did DTPA at pH 7.3 and about 50 to 100 times as much as did water. Correlations between DTPA extractable nutrients and rice uptake were significant only for Fe and Cu and declined during incubation. The changes in all variables during incubation were complex, being related to soil properties such as organic matter content, pH and mineralogy as well as to incubation conditions.
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  • 82
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    Plant and soil 114 (1989), S. 173-185 
    ISSN: 1573-5036
    Keywords: acidity ; aluminium ; mineral nutrition ; rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A study of the effect of increasing aluminium concentration in a dilute nutrient solution on various aspects of the mineral nutrient uptake by the rice plant has shown that aluminium exerts a stimulation on dry matter production and nutrient uptake until a concentration threshold was reached. The value of this threshold was influenced by nutrient solution composition and cultivar. Its location could be calculated by adjusting to the experimental points a rate law from enzyme kinetics on substrate inhibition curve. On the other hand, total uptake of aluminium and its concentration in the tops was a monotonic function of aluminium concentration in the nutrient solution, the effect of which was greatly enhanced by increased phosphate concentration. A sensitive cultivar accumulated more aluminium than a resistant one. The effect of phosphate on the alleviation of aluminium toxicity was slight in the range of concentration studied. Nitrogen uptake either as ammonium or nitrate nitrogen was clearly influenced by aluminium concentration when its instantaneous value was measured by the technique of the continuously flowing culture solution. The ammonium uptake rate of two cultivars different in sensitivity to aluminium was such that the sensitive variety took up less ammonium and acidified less the culture solution flowing through the root sysstem with a residence time of a few hours. Minor elements concentration in the tops of the rice plants did not seem to be greatly influenced by aluminium with the notable exception of manganese, the uptake of which was clearly depressed by increasing aluminium concentration. Attempts were made at using the speciation of the nutrient solutions with or without aluminium complexation by fluoride in order to rank the various ionic forms of aluminium according to their toxicity. It seems that the well-known result of primary toxicity due to the free Al-ion is also true for rice but that some toxicity is associated with the AlSO4-ion.
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  • 83
    ISSN: 1573-5036
    Keywords: legume-cereal association ; 15N ; nitrogen fixation ; nitrogen fertilization ; nitrogen transfer ; reference crop ; Vicia sativa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract This study was conducted to examine the effects of varying N rates and cropping systems (mixedversus pure stand) on the suitability of oats (Avena sativa L.) for estimating N2 fixed in sequentially harvested vetch (Vicia sativa L.) over two growing seasons (1984–85 and 1985–86). The N rates were, 20 and 100 kg N ha−1 in 1984–85 and 15 and 60 kg N ha−1 in 1985–86. In the 1984–85 season, vetch at maturity derived 76 and 63% N from fixation at the high and low N rates respectively. The corresponding values for the second season were 66 and 42%. Except in the 1985–86 season when some significantly higher values of % N2 fixed were estimated by using the reference crop grown at the higher (A-value approach) than at the lower N rate (isotope-dilution approach), both approaches resulted in similar measurements of N2 fixed. In the 1984–85 season, similar values of N2 fixed were obtained using either the pure or mixed stand oats reference crops. Although in the 1985–86 season, the mixed reference crop occasionally estimated lower % N2 fixed than pure oats, total N2 fixed estimates were always similar (P〈0.05). Thus, in general, N fertilization and cropping system of the reference crop did not significantly influence estimates of N2 fixation.
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  • 84
    ISSN: 1573-5036
    Keywords: Arthrobacter ; Azospirillum ; mixed culture ; nitrogen fixation ; phytohormones
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The production of phytohormone-like substances byAzospirillum brasilense andArthrobacter giacomelloi were investigated in single and mixed batch cultures under diazotrophic conditions. The mixed culture showed higher productivity of gibberellins and cytokinins.
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  • 85
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    Plant and soil 116 (1989), S. 129-131 
    ISSN: 1573-5036
    Keywords: 15N ; nitrogen fixation ; nitrogen partitioning ; translocationVigna unguiculata
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Two days after exposure of roots to15N labeled N2, partitioning of biologically fixed N into leaves, stems, peduncles, pods, roots and nodules was measured in the early pod development stage of cowpea (Vigna unguiculata (L.). The experimental objective was to determine the quantity of biologically fixed N that is incorporated into vegetative tissue before being mobilized to pods. For the three varieties of cowpea included in the experiment a maximum of 50% of the N, biologically fixed two days earlier, was contained in the pods. The remaining N was distributed throughout the vegetative portion of the plant with at least 30% in stems and leaves which indicates that much of the newly fixed N must cycle through a N pool in these tissues before reaching the pods.
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  • 86
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    Plant and soil 107 (1988), S. 25-30 
    ISSN: 1573-5036
    Keywords: alfalfa ; day length ; light intensity ; nitrogen fixation ; nitrogen transfer ; temperature ; timothy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Nitrogen fixation (NF) by alfalfa and nitrogen transfer (NT) from alfalfa to associated timothy was studied under different environmental conditions in controlled growth chambers, using the15N dilution technique. Evidence was obtained of NT from alfalfa to the associated timothy. Conditions that favored NF by alfalfa resulted in an increase in its NT. Of 3 different temperature regimes (25/20, 16/14, and 12/9°C day/night), 16–25/14–20°C was the best range for NF by alfalfa and resulted in the greatest NT. High light intensity (550 uE.m−2.sec−1) and long days (16–20 h) also caused increased NF by alfalfa and benefitting timothy more than in a regime of low light intensity (by shading 50% or 75%) or short days (12/12 or 16/8 h day/night). When the inoculated (Rhizobium meliloti) root systems of plants were kept free from other microorganisms (axenic condition) to minimize possible decomposition of dead tissues, lower NT from alfalfa was observed, especially at later cuts, compared to non-axenic plants. This suggests that both direct excretion and decomposition of dead alfalfa tissues are sources of N benefit from alfalfa to associated timothy.
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  • 87
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    Plant and soil 107 (1988), S. 95-99 
    ISSN: 1573-5036
    Keywords: CaSO4 ; Leucaena leucocephala ; lime ; NaCl ; nitrogen fixation ; salinity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Effects and interactions of varying CaSO4 and NaCl levels on growth and nitrogen fixation ofLeucaena leucocephala K8 were examined. Leucaena was grown in nutrient solution at four levels of CaSO4 (0.5, 1.0, 2.5 and 5.0 mM) and NaCl (1, 25, 50 and 100 mM) in randomized blocks with five replications. While NaCl significantly reduced plant growth, additions of CaSO4 increased plant height, leaf number, and biomass of salt treated plants. For the nonsaline treatments, high CaSO4 levels slightly depressed growth, which contradicts suggestions that Leucaena has a high calcium requirement. A significant calcium/sodium interaction was not seen for nodule number or weight. Nodule number was significantly depressed by 100 mM NaCl and nodule weight of the salt stressed plants significantly increased as CaSO4 concentration increased from 0.5 to 2.5 mM. Effects of NaCl and CaSO4 on nitrogen content of plant parts were inconclusive. The promotion of Leucaena salinity tolerance by addition of CaSO4 may be attributed to the effect of calcium in maintaing the selective permeability of membranes.
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  • 88
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    Plant and soil 107 (1988), S. 227-231 
    ISSN: 1573-5036
    Keywords: aluminium ; Bradyrhizobium sp. (Lotus) ; Lotus pedunculatus ; nitrogen fixation ; nodulation ; pH ; Rhizobium loti ; soil acidity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Measurements of multiplication in liquid culture indicated that fast-growing Lotus rhizobia (Rhizobium loti) were tolerant of acidity and aluminium (at least 50 μM A1 at pH 4.5). Slow-growing Lotus rhizobia (Bradyrhizobium sp. (Lotus)) were less tolerant of acidity but equally tolerant of A1. Both genera were able to nodulateLotus pedunculatus in an acid soil (pH 4.1 in 0.01M CaCl2) and the slow-growing strains were more effective than the fast-growing strains in this soil over 30 days.
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  • 89
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    Plant and soil 112 (1988), S. 129-135 
    ISSN: 1573-5036
    Keywords: alfisol ; inoculation ; Leucaena leucocephala ; nitrogen fertilizer ; nitrogen fixation ; nodulation ; Rhizobium ; shoot growth ; total nitrogen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Leonard jar, pot and field experiments examined the effects of inoculation and the influence of nitrogen fertilizer on nodulation, nitrogen fixation and growth ofLeucaena leucocephala (Lam.) de Wit at IITA, Ibadan, Nigeria. Leucaena responded to both inoculation and/or nitrogen application. Shoot growth and total N and P of inoculated plants were comparable to those of the highest N treatment, and the values were about 55% greater than those of uninoculated ones. Field data indicated that toal N yields of inoculated leucaena were increased by 50% with 40 or 80 kg ha−1 of N fertilizer. However, N fertilizer depressed N fixation by 56% as was expected from nodule mass data. N-fixation was delayed for about 8 weeks in the plots without N. Application of small amounts of N starter (20 ppm) proved to be beneficial to satisfy the plant need during the early stage of leucaena growth. The rhizobial strains IRc 1045 and IRc 1050 were effective, competitive and survived well in the field one year after their establishment.
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  • 90
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    Plant and soil 117 (1989), S. 195-200 
    ISSN: 1573-5036
    Keywords: acidity ; nitrogen fixation ; nodulation ; nodule occupancy ; Phaseolus vulgaris ; Rhizobium leguminosarum bvphaseoli ; strain competition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Two experiments were carried out to evaluate the effect of acidity on bean-Rhizobium competition for nodule sites. SevenPhaseolus vulgaris host cultivars differing in acid-pH tolerance were grown in sand culture, and irrigated using a sub-irrigation system and nutrient solutions of pH 4.5, 5.0, 5.5, and 6.0. A mixed inoculant of two antibiotically markedRhizobium leguminosarum bvphaseoli strains CIAT899 (acid-tolerant) and CIAT632 (acid-sensitive) was used. The acid-tolerant CIAT899 dominated CIAT632 in nodule occupancy across all cultivars and pH treatments. Although several of the varieties had previously been identified as PH-tolerant, and these cultivars performed better than those reported to be acid sensitive, all showed a marked increase in nodulation and plant development when the pH was raised from 4.5 to 6.0. The second experiment using a modified Leonard jar system varied the inoculation ratio between CIAT899 and UMR1116 (acid-sensitive, inefficient in N2-fixation) and contrasted nodulation response for the bean varieties ‘Preto 143’ (pH-tolerant) and ‘Negro Argel’ (pH-sensitive) at 3 pH treatments (4.5, 5.5, 6.5). There was a significant effect of host cultivar, ratio of inoculation, and pH on the percentage of nodule occupancy by each strain. At low pH CIAT899 had higher nodule occupancy than UM1116 in the variety ‘Negro Argel’ but had the same percentage of nodulation when the variety was ‘Preto 143’. Increasing the cell concentration of UMR1116 produced more inefficient nodules at all treatment combinations and reduced plant growth for both cultivars used.
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  • 91
    ISSN: 1573-5036
    Keywords: difference method ; isotope dilution ; Leucaena leucocephala ; nitrogen fixation ; Rhizobium inoculation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The amount of nitrogen fixed byLeucaena leucocephala (Lam.) de Wit was assessed on an Alfisol at the International Institute of Tropical Agriculture located in southwestern Nigeria. Estimated by the difference method, nitrogen fixation of leucaena inoculated with Rhizobium strain IRc 1045 was 133 kg ha−1 in six months. Inoculation with Rhizobium strain IRc 1050 gave a lower nitrogen fixation of 76 kg ha−1. Fertilization with 40 and 80 kg N ha−1 inhibited nitrogen fixation by 43–76% and 49–71%, respectively. Estimates with the15N dilution method gave nitrogen fixation of 134 kg ha−1 in six months when leucaena was inoculated with Rhizobium strain IRc 1045 and 98 kg ha−1 for leucaena inoculated with Rhizobium strain IRc 1050. This nitrogen fixation represented 34–39% of the plant nitrogen. Inoculated leucaena derived 5–6% of its nitrogen from applied fertilizer and 56–54% from soil.
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  • 92
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    Plant and soil 117 (1989), S. 275-286 
    ISSN: 1573-5036
    Keywords: bronzing ; chloride ; iron toxicity ; magnesium ; Nigeria ; phosphorus ; potassium ; rice ; sulfate ; sulfur ; tropics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Rice plants with bronzing, collected from fields in central and southern Nigeria, where the soils consisted of Tropaquent, Tropaquult and Tropaquept, showed higher iron and lower potassium, phosphorus, and magnesium concentrations than plants with little or no bronzing. Pot experiments with the soils indicated that the severity of the bronzing was affected not only by the iron concentration in the shoots but also by the potassium concentration. The application of chloride compounds to the soil increased severity of the bronzing and lead to deterioration of growth, whereas the application of sulfate compounds was beneficial. The application of potassium sulfate reduced the severity of bronzing and increased the dry matter production of rice plants grown in the field. The concentration and accumulation of potassium in the shoots increased when the bronzing severity decreased and the iron concentration was decreased by the dilution effect caused by the increased dry matter production.
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  • 93
    ISSN: 1573-5036
    Keywords: actinorhizal plants ; Allocasuarina ; Casuarina ; Frankia ; nitrogen fixation ; nodules ; symbiosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Sandy alluvial soils in a floodplain supporting a native stand ofCasuarina cunninghamiana Miq. produced about three times as many nodulated seedlings and more than twice as many nodules per nodulated seedling on roots of baitedCasuarina spp. than did clay loam red earth soils from the adjacent valley slope. Moist and well-aerated subsurficial alluvial sands had the greatest nodulation capacity of all the soils sampled. For all topographic positions, soil samples from depths greater than 20 cm promoted 76% more nodulated Casuarina seedlings than samples from the surficial 20 cm. Seedlings of three provenances ofC. cunninghamiana, together with seedlings ofC. glauca Sieb. ex Spreng.,C. cristata F. Muell ex Miq. andC. obesa Miq. developed significantly more nodules per pot and nodules per nodulated seedling in soils from this locale than seedlings of twoCasuarina equisetifolia Forst. provenances. Seedlings of two provenances ofAllocasuarina torulosa (Ait.) L. Johnson had fewer than 1% nodulated seedlings, a significantly lower level by far than that ofCasuarina seedlings.A. torulosa provenances also had significantly fewer nodulated seedlings per pot and nodules per nodulated seedling than all Casuarina hosts excepting one poorly-nodulated provenance ofC. equisetifolia. Nodulated seedlings of allCasuarina species had the capacity to fix atmospheric N2, as indicated by acetylene-reduction capability. The presence of yellow cladodes and low rates of acetylene reduction per plant forC. cristata Miq. suggest that this association was poorly effective.
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  • 94
    ISSN: 1573-5036
    Keywords: Alnus incana ; field ; Frankia ; growth ; intact plants ; nitrogenase activity ; nitrogen fixation ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The nitrogen-fixing grey alder,Alnus incana (L.) Moench, has a potential use in forest soil restoration and as part of energy forestry plantations. As a first step to estimate nitrogen fixation byA. incana under field conditions we performed studies on nitrogenase activity and its possible relation to abiotic factors and growth of the alders. Nitrogenase activity was measured as acetylene reduction activity (ARA) on eleven 1-year-old seedlings ofA. incana inoculated with a local source ofFrankia and planted in an experimental plot located in Umeå, northern Sweden. Each alder was planted into an open-ended cylinder which was closed with a gas tight lid around the stem base to serve as cuvette during ARA measurements. Propane served as tracer gas. ARA was measured in the middle of the day at 15 occasions during 26 June to 29 September 1987. Growth was recorded as leaf area and top shoot length at each ARA measurement until the end of August. Weather conditions were recorded for the whole growing season. Maximal ARA was recorded in late July or early August and ranged from 1.86 to 106μmol C2H4plant−1h−1. Final leaf area ranged from 0.022 to 0.124 m2. A relationship between ARA and the number of hours of sunshine during the same day was observed. ARA in relation to soil temperature increased during the study period, except for the last measurements. ARA in relation to leaf area was initially high but decreased later on. It is suggested that as leaves got older their contribution to photosynthesis per unit leaf area decreased and their potential to deliver nitrogen for retranslocation within plant increased. Both of these events would cause reduced ARA per unit leaf area. The data on ARA, growth, and abiotic factors taken together supported the view that sunshine and weather conditions affected photosynthesis and thereby delivery of assimilates to the nodules.
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  • 95
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    Plant and soil 120 (1989), S. 49-55 
    ISSN: 1573-5036
    Keywords: A-value ; drought ; nitrogen fixation ; water stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The N accumulation and growth of regularly watered soybean (Glycine max. L.) plants were compared with those grown under various durations of drought stress varying from 14 to 47 days (D). The stresses were imposed between the V3 (three nodes) and R7 (physiological maturity) growth stages. The stress was defined as eithermild, moderate orsevere, corresponding to (i), a single drought cycle from V3 to R2 (18 D) or R5 to R7 (14 D), (ii) double cycle from V3 to R5 (33 D) or R2 to R7(29 D), and (iii) three continuous cycles from V3 to R7 (47 D), respectively. Plants were harvested at the R7 stage (76 days after planting). The A-values measured by the non-nodulated plants under all treatments were similar (P〈0.05), indicating that the available amount of soil N was not changed by drought. However, the A-values assessed by the nodulated plants (which included the N2 fixed), differed significantly among treatments. Except under the longest stress condition, all plants (in both genotypes) absorbed similar amounts of soil N, but N2 fixed in the nodulated plants differed, significantly among treatments. The regularly-watered plants derived the highest amount (68 mg plant−1) and proportion (46.1%) of N from fixation, and the water stresses resulted in significant reductions in N2 fixed. Although the growth of both nodulated and non-nodulated plants, was adversely affected by water stress, this was not as great as was the effect on N2 fixation. Nitrogen fixation was the most sensitive parameter to drought, followed by plant growth, and the least sensitive was soil N uptake.
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  • 96
    ISSN: 1573-5036
    Keywords: actinorhizae ; Casuarina ; Frankia ; isolation ; nitrogen fixation ; spores
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Four species of Casuarina were raised in the glasshouse and inoculated with nodules collected from nine different geographical areas within Australia. Isolations ofFrankia were attempted from 10 of the Casuarina-Frankia nodule combinations using two methods, a nodule dissection and a filtration method. With both techniquesFrankia isolates were obtained from four of the 10Frankia sources. Spores were not observed in sections of nodules from the four sources from whichFrankia was isolated, whereas spores were observed in the remaining six nodule sources. For selected nodule sources a range of isolation media were tried, but no improvement in the isolation success rate was achieved. The effect of host species on ease of isolation was studied. The results obtained suggested it was theFrankia strain and not the host plant species which determined the ease of isolation from Casuarina nodules.
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  • 97
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    Nutrient cycling in agroecosystems 12 (1987), S. 53-65 
    ISSN: 1573-0867
    Keywords: balance sheet ; 15N ; urea ; rice ; vertisols ; soil organic carbon ; nitrogen losses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A glasshouse experiment was conducted to study the balance sheet of15N labelled urea at three rates (zero, 31.48 and 62.97 mmol N pot−1) applied to rice under flooded conditions with two moisture regimes (continuous and alternate flooding) using three Australian vertisols differing in organic carbon level. Walkley-Black organic carbon values for the three soils were 0.65, 2.13 and 3.76 for the low carbon (LC), medium carbon (MC) and high carbon (HC) soils respectively. Rice dry weight and nitrogen uptake was significantly affected by N fertilizer rates, water regimes and soils. Alternate flooding gave much lower dry weight and nitrogen uptake than continuous flooding and the LC soil gave lower dry weight and nitrogen uptake than for the MC and HC soils. Recovery of15N labelled urea fertilizer in the rice plant was low (15.4 to 38.4%) and the15N urea not accounted for in the plant or soil and presumed lost was high (36.2 to 76.0%). Recovery was lower and loss higher under alternate flooding and for the LC soil. There was no effect of fertilizer rate. The results obtained stress the need for careful management to reduce losses of nitrogen fertilizer, particularly for soils low in organic carbon.
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  • 98
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    Nutrient cycling in agroecosystems 13 (1987), S. 13-29 
    ISSN: 1573-0867
    Keywords: rice ; algicide ; pH ; alkalinity ; urea fertilizer ; NH3 volatilization ; N loss ; fertilizer efficiency ; algae ; terbutryne
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract When urea or ammoniacal-N fertilizers are applied to the floodwater of a rice crop, fertilizer use efficiency is often reduced because there are substantial losses of NH3 by volatilization. As pH rises the potential loss increases exponentially due to the increasing dominance of volatile NH3 gas in equilibrium with NH 4 + . We postulate that the daytime pH rise is caused mainly by photosynthesis of algae and Cyanobacteria, and that addition of a suitable photosynthetic inhibitor, concurrently with fertilizer, should suppress the pH rise, thus conserving N in the form of the non-volatile NH 4 + . We selected terbutryne (2-(tert-butylamino)-4-(ethylamino)-6-(methylthio)-s-triazine) as the most promising inhibitor. In rice floodwater fertilized with urea the addition of terbutryne dampened the diurnal fluctuation in pH for 6 days and significantly increased the ammoniacal-N (AN) concentration measured in the floodwater. The concentration of ammonia gas in the air in equilibrium with the water,ϱ 0, which is proportional to the gaseous flux of NH3 at a given wind speed, was substantially reduced by terbutryne addition. Maximum values were reduced by over 50%. Terbutryne reduced the calculated cumulative NH3 emission by 43%, relative to the fertilizer (N + P) control. Terbutryne also suppressed photosynthetic oxygen production. Therefore, it may reduce N fertilizer losses by inhibiting nitrification, an aerobic process, so retarding subsequent denitrification losses of gaseous nitrogen and nitrogen oxides.
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  • 99
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    Nutrient cycling in agroecosystems 10 (1986), S. 193-202 
    ISSN: 1573-0867
    Keywords: 15N fertilizer dilution ; nitrate-N ; nitrogen fixation ; pea ; yield
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The influence of nitrate N supply on dry matter production, N content and symbiotic nitrogen fixation in soil-grown pea (Pisum sativum L.) was studied in a pot experiment by means of15N fertilizer dilution. In pea receiving no fertilizer N symbiotic nitrogen fixation, soil and seed-borne N contributed with 82, 13 and 5% of total plant N, respectively. The supply of low rates of nitrate fertilizer at sowing (“starter N”) increased the vegetative dry matter production, but not the seed yield significantly. Nitrogen fixation was not significantly decreased by the lower rates of nitrate but higher rates supplied at sowing reduced the nitrogen fixation considerably. Applying nitrate N at the flat pod growth stage increased the yield of seed dry matter and N about 30% compared to pea receiving no nitrate fertilizer. Symbiotic nitrogen fixation was reduced only about 11%, compared with unfertilized pea, by the lowest rate of nitrate at this application time. The pea very efficiently took up and assimilated the nitrate N supplied. The average fertilizer N recovery was 82%. The later the N was supplied the more efficiently it was recovered. When nitrate was supplied at the flat pod growth stage 88% was recovered, and 90% of this N was located in the seeds.
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  • 100
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    Nutrient cycling in agroecosystems 15 (1988), S. 101-109 
    ISSN: 1573-0867
    Keywords: rice ; urea supergranules ; sulfur-coated urea ; placement
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Conventional as well as modified nitrogen sources and application methods were evaluated under rainfed lowland conditions in heavy clay soils of Bihar, India for 4 years. Modified nitrogen sources, viz. sulfur-coated urea (SCU) and urea super-granules (USG) were tested against prilled urea (PU) under four levels of N (0, 29, 58 and 87 kg N/ha) in the wet season. A high yielding nonphotoperiod sensitive, long duration variety ‘Pankaj’ was grown in all the four years. Point placement of USG and basal incorporation of SCU resulted in significantly higher panicle numbers per square meter, 100 grain weight and grain yield at all the levels of N tested. The unfilled grain percentage was lower in USG and SCU treatments. Regression analysis using a multifertilizer response model (MRM) showed that rice responded significantly to PU in three years out of four years, to SCU in four years and USG in three years. Economic analysis viz. input and output analysis based on the price of fertilizer (1 kg N as PU at $0.5; USG and SCU costing 10% more than PU), rough rice (ranging from 18.0 to 20.0 $ per ton) and labour wages at 1.0 $ per man day unit, also showed that USG and SCU are more input efficient than PU.
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