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In view of the significance of agricultural soils in affecting global C balance, the impact of manipulation of the quality of exogenous inputs on soil CO2–C flux was studied in rice–barley annual rotation tropical dryland agroecosystem. Chemical fertilizer, Sesbania shoot (high quality resources), wheat straw (low quality resource) and Sesbania + wheat straw (high + low quality), all carrying equivalent recommended dose of N, were added to soil. A distinct seasonal variation in CO2–C flux was recorded in all treatments, flux being higher during rice period, and much reduced during barley and summer fallow periods. During rice period the mean CO2–C flux was greater in wheat straw (161% increase over control) and Sesbania + wheat straw (+129%) treatments; however, during barley and summer fallow periods differences among treatments were small. CO2–C flux was more influenced by seasonal variations in water-filled pore space compared to soil temperature. In contrast, the role of microbial biomass and live crop roots in regulating soil CO2–C flux was highly limited. Wheat straw input showed smaller microbial biomass with a tendency of rapid turnover rate resulting in highest cumulative CO2–C flux. The Sesbania input exhibited larger microbial biomass with slower turnover rate, leading to lower cumulative CO2–C flux. Addition of Sesbania to wheat straw showed higher cumulative CO2–C flux yet supported highest microbial biomass with lowest turnover rate indicating stabilization of microbial biomass. Although single application of wheat straw or Sesbania showed comparable net change in soil C (18% and 15% relative to control, respectively) and crop productivity (32% and 38%), yet they differed significantly in soil C balance (374 and −3 g C m−2 y−1 respectively), a response influenced by the recalcitrant and labile nature of the inputs. Combining the two inputs resulted in significant increment in net change in soil C (33% over control) and crop yield (49%) in addition to high C balance (152 g C m−2 y−1). It is suggested that appropriate mixing of high and low quality inputs may contribute to improved crop productivity and soil fertility in terms of soil C sequestration. 相似文献
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Seeds of two varieties (PUSA-212 and BG-256) of chickpea (Cicer arietinum L.) were treated with 0.03% concentration of hydrazine hydrate (HZ), methylmethane sulphonate (MMS) and sodium azide (SA)
for 6 h. The M2 generation was grown from single plant M1 progeny seeds. Five morphological mutants (dwarf, bushy, one sided branch, narrow leaf and gigas) were isolated in M2 generation. Some of these mutants may be directly used in selection whereas some are useful in combination breeding programs. 相似文献
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The influence of exogenous organic inputs on soil microbial biomass dynamics and crop root biomass was studied through two annual cycles in rice-barley rotation in a tropical dryland agroecosystem. The treatments involved addition of equivalent amount of N (80 kg N ha−1) through chemical fertilizer and three organic inputs at the beginning of each annual cycle: Sesbania shoot (high-quality resource, C:N 16, lignin:N 3.2, polyphenol+lignin:N 4.2), wheat straw (low-quality resource, C:N 82, lignin:N 34.8, polyphenol+lignin:N 36.8) and Sesbania+wheat straw (high-and low-quality resources combined), besides control. The decomposition rates of various inputs and crop roots were determined in field conditions by mass loss method. Sesbania (decay constant, k=0.028) decomposed much faster than wheat straw (k=0.0025); decomposition rate of Sesbania+wheat straw was twice as fast compared to wheat straw. On average, soil microbial biomass levels were: rice period, Sesbania?Sesbania+wheat straw>wheat straw?fertilizer; barley period, Sesbania+wheat straw>Sesbania?wheat straw?fertilizer; summer fallow, Sesbania+wheat straw>Sesbania>wheat straw?fertilizer. Soil microbial biomass increased through rice and barley crop periods to summer fallow; however, in Sesbania shoot application a strong peak was obtained during rice crop period. In both crops soil microbial biomass C and N decreased distinctly from seedling to grain-forming stages, and then increased to the maximum at crop maturity. Crop roots, however, showed reverse trend through the cropping period, suggesting strong competition between microbial biomass and crop roots for available nutrients. It is concluded that both resource quality and crop roots had distinct effect on soil microbial biomass and combined application of Sesbania shoot and wheat straw was most effective in sustained build up of microbial biomass through the annual cycle. 相似文献
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Satnam Singh P. D. Rekha A. B. Arun Asif Hameed Sonu Singh Fo-Ting Shen Chiu-Chung Young 《Biology and Fertility of Soils》2011,47(4):419-426
Monosodium glutamate wastewater (MSGW) was used as a culture medium for Azospirillum rugosum strain IMMIB AFH-6 inoculant (In) by optimizing the dilution at 2.5% and pH 7.0 ± 0.1. A. rugosum growth studies were carried out in shake flasks and subsequently tested for plant growth promotion by seed germination bioassay
and greenhouse pot experiments. The highest colony-forming units (cfu) 8.58 and 8.87 log cfu mL−1, respectively, at 48 h of growth were recorded in MSGW and MSGW with yeast extract 0.04%. Seed bioassay results revealed
that A. rugosum grown on MSGW stimulated the root and shoot elongation of maize (Zea mays L.) and pai tsai (Brassica chinensis L.). Pai tsai recorded significantly higher dry matter production when treated with A. rugosum and chemical fertilizers than control. The MSGW is a suitable culture medium for A. rugosum growth, and it is comparable to commercial media when tested for agricultural production. 相似文献
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Ramakrishnappa Archana Kunnummal Kurungara Vinod Subbaiyan Gopala Krishnan Elangovan Devi Chandra Vadhana Prolay Kumar Bhowmick Vikram Jeet Singh Ranjith Kumar Ellur Lekshmy Sathee Pranab Kumar Mandal Haritha Bollinedi Shekharappa Nanda Kumar Sonu Mariappan Nagarajan Ashok Kumar Singh 《Plant Breeding》2023,142(3):312-326
Functional stay-green (FSG) is characterized by delayed senescence during the reproductive stage in rice. A recombinant inbred line (RIL) population derived from ‘Pusa 677’/‘PSG16’ was used to study the genetics of FSG in a rice mutant, ‘PSG16’. The RILs exhibited significant variation under two N regimes for agro-morphological traits, leaf chlorophyll content, flowering time, yield components and nitrogen (N) use. Using a genome wide linkage map spanning 1910.8 cM with 104 polymorphic markers, we have mapped six major quantitative trait loci (QTLs). One robust QTL on chromosome 1 was associated consistently across different N regimes with chlorophyll content and flowering time. The QTL on chromosome 7 was associated with grain number, whereas the QTL on chromosome 6 was found related to N harvest index and spikelet fertility. Although ‘PSG16’ showed a clear advantage in grain yield as well as having better N assimilation, we could not establish a direct genetic relationship SG trait and N use. Based on the QTL information, FSG trait of ‘PSG16’ could be useful in deciphering multiple stress responses in rice. 相似文献
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