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  • Electronic Resource  (6)
  • Azolla  (3)
  • rice yield  (3)
  • 1
    Electronic Resource
    Electronic Resource
    Nitrogen fixation and balance studies of rice soil (1987)
    Springer
    Biology and fertility of soils 4 (1987), S. 15-19 
    Details
    ISSN: 1432-0789
    Keywords: Nitrogen fixation ; N-balance studies ; Azolla ; Blue-green algae ; Chemical N fertilization ; Rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A nitrogen balance study conducted in ceramic pots under net house conditions for four seasons showed that flooded rice soil leaves a positive nitrogen balance (N increase) in soil after rice cropping in both fertilized and unfertilized soil. Recovery of nitrogen from rice soil was more than its input in unfertilized soil, but it was reverse in fertilized soil. Incorporation of Azolla or BGA twice as basal and 20 days after transplanting (DAT) alone or in combination showed higher nitrogen balance and N2-fixation (N gain) in soil than in that where it was applied once either as basal or 20 DAT. Planted soil showed more N2-fixation than that of fallow rice, and flooded soil fixed more nitrogen in comparison to non-flooded soil in light but less in dark. Soil exposed to light fixed more nitrogen than that of unexposed soil in both flooded and non-flooded conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00280345
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  • 2
    Electronic Resource
    Electronic Resource
    Influence of Azolla management on the growth, yield of rice and soil fertility (1987)
    Springer
    Plant and soil 102 (1987), S. 41-47 
    Details
    ISSN: 1573-5036
    Keywords: Azolla pinnata ; dual cropping ; N2-fixation ; spacing ; rice yield
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A field experiment conducted at Central Rice Research Institute, Cuttack, during three successive seasons showed that with the 120-day-duration variety Ratna two dual crops ofAzolla pinnata R. Brown (Bangkok isolate) could be achieved 25 and 50 days after transplanting (DAT) by inoculating 2.0 t ha−1 of fresh Azolla 10 and 30 DAT respectively. One basal crop of Azolla could also be grown using the same inoculum 20 days before transplanting (DBT) in fallow rice fields. The three crops of Azolla grown—once before transplanting and twice after transplanting—gave an average total biomass of 38–63 and 43–64 t ha−1 fresh Azolla containing 64–90 and 76–94 kg N ha−1 respectively in the square and rectangular spacings. Two crops of Azolla grown only as a dual crop, on the other hand, gave 26–39 and 29–41 t ha−1 fresh Azolla which contained 44–61 and 43–59 kg N ha−1 respectively. Growth and yield of rice were significantly higher in Azolla basal plus Azolla dual twice incorporated treatments than in the Azolla dual twice incorporation, Azolla basal plus 30 kg N ha−1 urea and 60 kg N ha−1 urea treatments. Azolla basal plus 30 kg N ha−1 urea and 60 kg N ha−1 urea showed similar yields but Azolla dual twice incorporation was significantly lower than those. The different spacing with same plant populations did not affect growth and yield significantly, whereas Azolla growth during dual cropping was 8.3 and 64% more in the rectangular spacing than in the square spacing in Azolla basal plus Azolla dual twice incorporation and Azolla dual twice incorporation treatments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02370898
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  • 3
    Electronic Resource
    Electronic Resource
    The response of rice to the growth and nitrogen fixation inAzolla caroliniana andAzolla pinnata at varying rates of phosphate fertilization (1989)
    Springer
    Plant and soil 114 (1989), S. 205-209 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02220799
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  • 4
    Electronic Resource
    Electronic Resource
    Comparative efficiency of Azolla, blue-green algae and other organic manures in relation to N and P availability in a flooded rice soil (1981)
    Springer
    Plant and soil 62 (1981), S. 35-44 
    Details
    ISSN: 1573-5036
    Keywords: Available N and P ; Azolla ; Blue-green algae ; Mineralization ; Organic manures ; Rice soil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Pot incubation study with fresh Azolla (Azolla pinnata-India and Vietnam isolates,A. mexicana andA. filiculoides), blue-green algaAulosira sp., green manureSesbania cannabina, Azolla compost, farm yard manure and ammonium sulphate was conducted under flooded condition at CRRI, Cuttack keeping an equivalent amount of 25 ppm N through all the amendments where changes in availability of N and P, C∶N ratio and pH were recorded. Application of chemical N-fertilizer recorded a release of about 87% NH4 +−N at 10th day of flooding which gradually decreased and reached the minimum of 6% at 50 days. The C∶N ratio of the organic manures ranged between 9–10 favouring release of NH4 +−N and among theAzolla speciesA. pinnata isolates released NH4 +−N more efficiently thanA. filiculoides andA. mexicana. A. pinnata Indian isolate released maximum of 88% NH4 +−N, whereas Vietnam isolate recorded 77% at 40 days of flooding; green manure on the other hand, reached a maximum of 50% release at 50 days. The blue-green alga recorded a gradual increase and attained the maximum release of 38% at 40 days of flooding. Farmyard manure recorded a highest NH4 +−N release of 69% at 20 days of flooding and gradual decrease thereafter, whereas Azolla compost released 41% at 40 days of flooding. Soil amended with fresh organic matter achieved reduction upto a pH of 7.2 after 50 days of flooding, whereas the pH in Azolla compost and farmyard manure amendment was 〈7. The P availability increased from 20th day onwards and reached the highest values of 26 and 18 ppm in the fresh organic matter and compost amended soil respectively after 40–50 days of flooding. The cumulative release of available P was found superior in fresh Azolla incorporation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02205023
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  • 5
    Electronic Resource
    Electronic Resource
    Growth and acetylene reduction activity ofAzolla caroliniana Willd. as influenced by split applications of urea fertilizer and their response on rice yield (1988)
    Springer
    Nutrient cycling in agroecosystems 18 (1988), S. 189-199 
    Details
    ISSN: 1573-0867
    Keywords: Azolla caroliniana ; N2-fixation ; rice yield ; crop N uptake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Experiment with different split applications of 40 kg N ha−1 of urea (U) at transplanting:30 days after transplanting:40 days before crop maturity with different proportions of 50:25:25, 25:50:25 and 0:50:50 splits, with and without Azolla, carried out for two consecutive seasons, revealed that fresh weight (FW), N2-fixation measured by acetylene reduction activity (ARA) and N yield of newly introducedAzolla caroliniana were higher with 0:50:50 treatment followed by 25:50:25 and 50:25:25.Azolla was unincorporated and left for self decomposition. The crop yield (grain yield, straw yield) and crop N uptake data indicated that among the no Azolla treatments, the use of 50:25:25 split resulted in highest crop yield and crop N uptake followed by 25:50:25 and 0:50:50 treatments, while these parameters recorded maximum value with 25:50:25 split in combination with Azolla followed by 50:25:25 and 0:50:50 treatments. The use of Azolla increased crop yield and crop N uptake significantly over no Azolla treatments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01049513
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  • 6
    Electronic Resource
    Electronic Resource
    Symbiotic algal nitrogenase activity and heterocyst frequency in sevenAzolla species after phosphorus fertilization (1988)
    Springer
    Hydrobiologia 169 (1988), S. 313-318 
    Details
    ISSN: 1573-5117
    Keywords: Azolla ; symbiont ; Anabaena azollae ; heterocyst ; acetylene reducing activity ; phosphorus ; fertilization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Seven species ofAzolla (A. caroliniana, A. microphylla, A. nilotica, A. filiculoides, A. mexicana, A. rubra, A. pinnata the last from both Malaysia and India) grown in pots of flooded soil were subjected to three different treatments with respect to P: none, single application, split application. The experiments were carried out under greenhouse conditions. Heterocyst frequency inAnabaena azollae and acetylene reducing activity (ARA) were studied in successiveAzolla leaves. Both variables increased from the first leaf (shoot apex) to the last one (before branch) in all species in the presence or absence of P. However, heterocyst frequency, ARA andAzolla biomass were all less in the treatment lacking P. Heterocyst frequency inA. azollae, ARA and biomass ofAzolla were higher when P was applied in split doses than in the other treatments.Azolla plants exhibited more ARA than the isolated leaves.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00007554
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