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41.
ABSTRACT

Thermo-chemical conversion of crop residues to produce biochar is an emerging strategy in the context of sustainable phosphorous (P) use and residue management. An incubation study for 90 d was conducted to investigate the effects of rice-residue biochar (0, 10, 20 and 40 g kg?1) in combination with inorganic-P (KH2PO4) (0, 25 and 50 mg kg?1) on phosphorous availability in medium- and high-P status soils. Increasing biochar addition rates alone or in combination with inorganic-P resulted in a significant increase in P pools, i.e. plant available P or Olsen-P (from 8 to 132 mg kg?1 in medium-P and 15 to 160 mg kg?1 in high-P soils), microbial biomass P and various mineral-bound inorganic-P fractions in the order (Ca-P > organic-P > Al-P > loosely held/soluble-P > Fe-P > reductant soluble-P). Further, lower phosphatase activity (19–50%) with increasing rates of biochar addition in both soils elucidates the ability of biochar to act as a long-term source of available P in the experimental soils. The results demonstrate that rice-residue biochar can directly or indirectly enhance the status of available P in soils and hence can be used as a beneficial amendment to meet the crop P demand.  相似文献   
42.
A field experiment was conducted at farmer's field in Mollisols of Tarai soils in Uttarakhand (India), to assess the direct and residual effect of sulfur fertilization in wheat-soybean cropping sequence. Four levels of sulfur (S; 0, 15, 30, and 45 kg ha?1) were applied to main crop (wheat) along with recommended dose of nitrogen (N), phosphorous (P), and potassium (K). The direct and residual effect of sulfur at highest level showed 27 and 6 percent increase in grain yield of wheat and soybean over control, respectively. The increase in grain yield of wheat was significant at each sulfur level. The direct as well as residual effect of sulfur showed significant increase in sulfur concentration and its uptake by grain and straw except increase in sulfur concentration and uptake by soybean straw. In wheat-soybean cropping sequence, the agronomic efficiency and apparent sulfur recovery decreased with increase in levels of sulfur, but the percent response increased with increasing sulfur application. Different forms of sulfur such as total sulfur, organic sulfur, calcium chloride extractable sulfur, potassium dihydrogen phosphate extractable sulfur, and non-sulfate sulfur in post-harvest soil increased according to sulfur level applied but it decreased under control and also after residual crops. The buildup of sulfur in surface soils was greater than in the deeper soils. Application of sulfur showed the positive sulfur balance and it increased with increase in sulfur level, while it was negative under control. A major portion (46–62%) of applied sulfur contributed to increase in sulfur content of root zone soil followed by unaccounted component (25–40%) and small portion (11–18%) was absorbed by wheat plant as uptake.  相似文献   
43.
Commercial grade zinc (Zn) sulfate hepta hydrate (ZnSHH) is the most widely used source of Zn in India and several other countries for amelioration of Zn deficiency in crops. However, it releases water of hydration at temperature above 30°C and forms lumps on storage, which make it difficult to handle it and apply in fields. Therefore, conditioning of ZnSHH with ZnO and neem oil reduces the release of water of hydration and prevents lumps formation and can be well stored. Field experiments were conducted at the research farm of the Indian Agricultural Research Institute, New Delhi, India during rice growing seasons (July-November) of 2009 and 2010 to study the effect of conditioning ZnSHH with ZnO and neem oil on growth, productivity and Zn fortification of rice (Oryza sativa) grain and uptake by Basmati rice ‘Pusa 1121’. The experiment was conducted in a randomized block design with 3 replications comprised of 9 treatments of Zn fertilization. The present study shows that when conditioned with 2% ZnO and 4% neem oil ZnSHH improved yield attributes, grain and straw yields, Zn uptake and partial factor productivity (PFP), agronomic efficiency (AE), recovery efficiency (RE), and physiological efficiency (PE) of Zn in Basmati rice ‘Pusa 1121’. In general, ZnO was inferior to ZnSHH. Application of ZnSHH conditioned with 2% ZnO and 4% neem oil can be a better source of Zn for transplanted puddled Basmati rice on Zn deficient soils.  相似文献   
44.
Present investigation evaluates the effect of organic fertilization (OF), integrated nutrient management (INM) practice, and recommended dose of chemical fertilization (CF) on changes in soil organic phosphorus (P) and its fractions under rice (Oryza sativa L.)–wheat (Triticum aestivum L.) cropping system. The 4-year experiment (2009–2013), under split-plot design, showed that OF did not increase the total P or total organic P content of soil under either of the test crops. However, OF maintained the higher level of labile organic P and moderately labile organic P in soil under wheat the moderately stable organic P and highly stable organic P was highest in paddy soil under CF practices (11.34 and 7.77 μg g?1, respectively) followed by wheat. The P concentration in organically grown rice or wheat grain was increased significantly compared with their CF counterparts. The productivity economics for rice and wheat crops showed INM fertilization to be more economical than OF.  相似文献   
45.
Estimation of sediment load from Himalayan basins is of considerable importance for the planning, designing, installation and operation of hydro-power projects, including management of reservoirs. In the present study, an assessment of physical and chemical load, sediment yield and erosion rate has been undertaken at eight different locations in the Sainj and Tirthan watersheds. The analysis revealed that the maximum load was transferred during the monsoon season. Moreover, the estimated average chemical erosion rate of the Sainj (83 t km− 2 yr− 1) and Tirthan (80 t km− 2 yr− 1) watersheds were higher than that of the Indian average (69 t km− 2 yr− 1) representing all the rivers. Both watersheds were eroding physically and chemically at a faster rate than that of the world global average erosion rate (185 t km− 2 yr− 1). The flattish nature of the channels in some segments of these watersheds showed a lower transport of sediments, where as the constricted segments having steep bed slopes increased the velocity of flow and the sediment transport rate. These findings have important implications for water resource management in the context of sediments mobilization, erosion, channel management, ecological functions and operation of the hydro-power projects in the Lesser Himalayan region.  相似文献   
46.
Grain legumes, the important constituents of sustainability‐based cropping systems and energy‐limited vegetarian diets have long been the subject of scientific research. Tremendous technological strides were made in the so‐called orphan crops, in terms of both varietal improvement and generation of basic information. Despite recalcitrancy and high genotype dependency, in vitro culture techniques such as organogenesis, in vitro mutagenesis, embryo rescue and in vitro gene transfer have been deployed for improvement of several grain legumes and these played an important role in introgression of desirable genes from related and distant species and creation of additional genetic variability. Stable and reproducible regeneration protocols resulted in the development of genetically modified chickpea, pigeon pea, cowpea, mungbean, etc., while embryo rescue was deployed successfully for recovery of interspecific recombinants, a few of them exploited for the development of commercial cultivars. Nevertheless, doubled haploidy witnessed limited success and protoplast regeneration and in vitro mutagenesis remained of academic interest. The present review focuses on the progress, achievements, constraints and perspectives of using in vitro technology in grain legume improvement.  相似文献   
47.
At present, testing for distinctness, uniformity and stability (DUS) of crop varieties relies on a set of morphological characters. These characters suffer fromthe limitations of number, interaction with the environment in which the variety grows and subjectivity in decision-making. The potential of DNA-based markers such as sequence tagged microsatellite site (STMS), for establishing DUS merits investigation. In the present study, a set of 55 mapped STMS markers, selected from 12 linkage groups of rice genome, was used to examine distinctness of 23 aromatic rice genotypes including the commercially important Basmati varieties. Forty-one of these markers (74.5%) showed polymorphism between the varieties. The number of alleles per locus ranged from 2–4 with an average of 2.3. The polymorphism information content (PIC) of the markers varied from 0.083 to 0.665 with an average of 0.338. All the varieties could be differentiated from each other at a low probability (0.07×10-13) of identical match by chance. The marker-based clustering of the varieties corresponded with the known phenotypic classification, thereby providing confidence in the distinctness established by the mapped STMS markers. The utility of these markers to study uniformity and stability was analysed using a commercially important crossbred Basmati rice variety Pusa Basmati 1(IET-10364) that contributes about 40–50% of Basmati rice export from India. Genotyping of twenty individual plants, grown from the nucleus, breeder, foundation, certified and farmer's saved seed samples using all the 55 markers revealed no variation among the plants. These observations suggested that the set of mapped markers employed in this study could be further used for establishing distinctness of aromatic rice varieties and for studying DUS of the important commercial variety Pusa Basmati 1. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   
48.
Sustainable soil and crop management practices that reduce soil erosion and nitrogen (N) leaching, conserve soil organic matter, and optimize cotton and sorghum yields still remain a challenge. We examined the influence of three tillage practices (no-till, strip till and chisel till), four cover crops {legume [hairy vetch (Vicia villosa Roth)], nonlegume [rye (Secaele cereale L.)], vetch/rye biculture and winter weeds or no cover crop}, and three N fertilization rates (0, 60–65 and 120–130 kg N ha−1) on soil inorganic N content at the 0–30 cm depth and yields and N uptake of cotton (Gossypium hirsutum L.) and sorghum [Sorghum bicolor (L.) Moench]. A field experiment was conducted on Dothan sandy loam (fine-loamy, siliceous, thermic, Plinthic Paleudults) from 1999 to 2002 in Georgia, USA. Nitrogen supplied by cover crops was greater with vetch and vetch/rye biculture than with rye and weeds. Soil inorganic N at the 0–10 and 10–30 cm depths increased with increasing N rate and were greater with vetch than with rye and weeds in April 2000 and 2002. Inorganic N at 0–10 cm was also greater with vetch than with rye in no-till, greater with vetch/rye than with rye and weeds in strip till, and greater with vetch than with rye and weeds in chisel till. In 2000, cotton lint yield and N uptake were greater in no-till with rye or 60 kg N ha−1 than in other treatments, but biomass (stems + leaves) yield and N uptake were greater with vetch and vetch/rye than with rye or weeds, and greater with 60 and 120 than with 0 kg N ha−1. In 2001, sorghum grain yield, biomass yield, and N uptake were greater in strip till and chisel till than in no-till, and greater in vetch and vetch/rye with or without N than in rye and weeds with 0 or 65 kg N ha−1. In 2002, cotton lint yield and N uptake were greater in chisel till, rye and weeds with 0 or 60 kg N ha−1 than in other treatments, but biomass N uptake was greater in vetch/rye with 60 kg N ha−1 than in rye and weeds with 0 or 60 kg N ha−1. Increased N supplied by hairy vetch or 120–130 kg N ha−1 increased soil N availability, sorghum grain yield, cotton and sorghum biomass yields, and N uptake but decreased cotton lint yield and lint N uptake compared with rye, weeds or 0 kg N ha−1. Cotton and sorghum yields and N uptake can be optimized and potentials for soil erosion and N leaching can be reduced by using conservation tillage, such as no-till or strip till, with vetch/rye biculture cover crop and 60–65 kg N ha−1. The results can be applied in regions where cover crops can be grown in the winter to reduce soil erosion and N leaching and where tillage intensity and N fertilization rates can be minimized to reduce the costs of energy requirement for tillage and N fertilization while optimizing crop production.  相似文献   
49.
True-to-type clonal fidelity is one of the most important pre-requisites in micropropagation of crop species. Genetic fidelity of in vitro raised 45 plants of gerbera (Gerbera jamesonii Bolus) derived from three different explants, viz., capitulum, leaf and shoot tips, was assessed by 32 ISSR markers, for their genetic stability. Out of 32 ISSR markers, 15 markers produced clear, distinct and scorable bands with an average of 5.47 bands per marker. The markers designed from AG motif amplified more number of bands. The markers anchored at 3′ ends produced high number of consistent bands than unanchored markers. Fifteen ISSR markers generated a total of 3773 bands, out of which 3770 were monomorphic among all the clones. The Jaccard's similarity coefficient revealed that out of 45 clones derived from different explants, 44 were grouped into a single large cluster alongwith the mother plant with a similarity coefficient value of 1.00, whereas one clone (C38) remained ungrouped. The clones derived from capitulum and shoot tip explants did not show any genetic variation, whereas, one of the leaf-derived clones exhibited some degree of variation.  相似文献   
50.
In the present study, water and nitrogen interaction on soil profile water extraction and evapo-transpiration (ET) was investigated taking a field experiment on a clay loam soil (Typic Haplustept) at the Indian Agricultural Research Institute, New Delhi with four consecutive crops (maize-wheat-maize-wheat) taken from July 2002 to April 2004. Three levels of water regime, namely W1, W2 and W3 referring to limited, medium and maximum irrigation were applied to each crop depending on the seasonal rainfall and the critical crop growth stage. The three water regimes were used with five nitrogen levels from T1 to T5, (T1, 0% N; T2, 75% N; T3, 100% N; T4, 150% N; T5, 100% N from organic source) in a split plot design for the four crops grown in sequence.Significant water and nitrogen interaction was observed for ET and soil profile water extraction pattern. Averaged across nitrogen treatments, ET in W2 and W3 were higher by 17 and 26%, respectively than W1 in maize 2002 and by 12 and 19% in maize 2003. In case of wheat, ET in W2 and W3 were higher by 27 and 58% than W1 in 1st crop and by 37 and 70% in 2nd crop. The effect of nitrogen regime, however, was prominent in both crops of maize and wheat, with significantly higher profile soil moisture depletion in T4 of each water regime. In all cases, lowest water depletion was observed in control plots receiving 0% N.In both crops, water extraction from surface 60 cm was highest in W3 followed by W2 and W1. In maize, the % extraction from 0 to 60 cm layer varied from 71 to 76% (W1), 70-79% (W2) and 75-82% (W3), whereas the values for wheat were 70-77, 72-79 and 75-83% for W1, W2 and W3, respectively. The 90-120 cm layer contributed only 3-14% to total water extraction in both the crops. From 90 to 120 cm layer, higher extraction was observed in W1 as compared to W3. The extraction values in W1, W2 and W3 in maize were 9-13, 7-14 and 3-9, respectively, whereas the corresponding values in wheat were 8-14, 5-12 and 3-7% for the three water regimes. Effect of nitrogen treatments on water extraction from deeper layer was observed with higher extraction in highest fertilized treatment (T4) as compared to other treatments.  相似文献   
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