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81.
Anil Kumar Singh Rojalin Tripathy Usha Kiran Chopra 《Agricultural Water Management》2008,95(7):776-786
Crop simulation models can provide an alternative, less time-consuming and inexpensive means of determining the optimum crop N and irrigation requirements under varied soil and climatic conditions. In this context, two dynamic mechanistic models (CERES (Crop Environment REsource Synthesis)-Wheat and CropSyst (Cropping Systems Simulation Model)) were validated for predicting growth and yield of wheat (Triticum aestivum L) under different nitrogen and water management conditions. Their potential as N and water management tool was evaluated for New Delhi representing semi-arid irrigated ecosystems in the Indo-Gangetic Plains. The field experiment was carried out on a silty clay loam soil at the Research Farm of the Indian Agricultural Research Institute, New Delhi, India during 2000–2001 to collect the input data for the calibration and validation of both the models on wheat crop (variety HD 2687). The models were evaluated for three water regimes [I4 (4 irrigations within the growing season), I3 (3 irrigations within the growing season) and I2 (2 irrigations within the growing season)] and five N treatments (N0, N60, N90, N120 and N150). Both the models were calibrated using data obtained from the treatments receiving maximum nitrogen and irrigations, i.e., N150 and I4 treatments. The models were then validated against other water and nitrogen treatments. For performance evaluation, in addition to coefficient of determination (R2), root mean square error (RMSE), mean absolute error (MAE) and Wilmot's index of agreement (IoA) were estimated. Both CERES-Wheat and CropSyst provided very satisfactory estimates for the emergence, flowering and physiological maturity dates. For CERES-Wheat overall prediction (pooled result of the three water regimes) of grain yield was satisfactory with significant R2 values (0.88). The model, however, under estimated the biomass under all water regimes and N levels except for N0 level, under which biomass was overpredicted. CropSyst predicted yield and biomass of wheat more closely than CERES-Wheat. The combined RMSE for the three water regimes between predicted and observed grain yield was 0.36 Mg ha−1 for CropSyst as compared to 0.63 Mg ha−1 for CERES-Wheat. Similarly, RMSE between observed and predicted biomass by CropSyst was 1.27 Mg ha−1 as compared to 1.94 Mg ha−1 between observed and predicted biomass by CERES-Wheat. Wilmot's index of agreement (IoA) also indicated that CropSyst model is more appropriate than CERES-Wheat in predicting growth and yield of wheat under different N and irrigation application situations in this study. 相似文献
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The current global area equipped for irrigation provides 30–40% of the world's gross food output. Water used for plant irrigation may harbour plant pathogens and foster their spread. This represents a serious risk for crop health, with heavy socio‐economic consequences. More specifically to plant pathogenic bacteria (PPB), a range of species have been reported from irrigation systems and their potential role in epidemic development has long been recognized. However, only a few studies have been performed to date on the ecology of PPB in the context of water habitats. Consequently, current knowledge of the biology, ecology and epidemiology of PPB in irrigation water is poor. In light of this, an attempt is made to describe the most relevant information concerning the role of open irrigation systems in the survival and dissemination of PPB throughout the range of cultivations and the possible consequences for crop health. The information described in this paper will help to improve understanding on the overlooked role of irrigation water as a reservoir of PPB. 相似文献
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Peer Saba Manzoor Kiran Dube Rawat Virendra Kumar Tiwari Nalini Poojary Babitha Rani Asanaru Majeedkutty 《Aquaculture Research》2020,51(8):3244-3254
An experiment was conducted for 120 days to evaluate optimum dietary lipid requirements for gonadal maturation of Cyprinus carpio fed with varying dietary lipid levels under biofloc‐based systems (BFT). About 180 fingerlings (22 g ± 0.05) were randomly distributed in 15 tanks (300 L) at the rate of 48 no./m2 and fed with varying lipid levels (T1—4% lipid with BFT, T2—6% lipid with BFT, T3—8% lipid with BFT, T4—10% lipid with BFT, control—10% lipid without BFT). The C/N ratio of 20:1 was maintained using tapioca flour as carbon source. Biofloc units supplemented with 8% dietary lipid (T3) showed advanced maturation in terms of absolute fecundity (9,913 ± 7.62), relative fecundity (229.0/g ± 11.92), gonadosomatic index (24.47% ± 1.27), hepatosomatic index (1.97% ± 0.07), condition factor (0.02 g/cm3 ± 0.00) compared with control (clear water with 10% lipid) (p < .05). Histological observations of gonads also revealed that the biofloc groups with supplementation of 8% dietary lipid promoted gonadal maturation for female oocyte and 6% dietary lipid promoted maturation for males, compared with control (clear water with 10% lipid). The results obtained in this experiment elucidate that the biofloc improves gonadal maturation of common carp broodstock at a dietary supplementation with 8% lipid compared with conventional system of broodstock management. 相似文献
87.
ABSTRACTColletotrichum gloeosporioides is a major plant pathogen worldwide. It is known to cause anthracnose in many crop plants, which ultimately leads to significant yield loss. In the present study, a fungus was isolated from the infected mango leaf and identified by 28S rDNA sequencing as C. gloeosporioides. Seventy-five different essential oils (EOs) were tested against C. gloeosporioides to evaluate the antifungal activities. Fungal suspension was spread on Potato Dextrose Agar (PDA) and tested with 5 µL of different EOs on disc. The tested EOs against C. gloeosporioides showed various ranges of inhibitory activity. Amongst the tested 75 EOs, four EOs showed remarkably higher antifungal activities. Considering the promising utilities of these EOs, gas chromatography–mass spectral (GC-MS) analysis was performed and the probable role of the key components of the EOs in antifungal activities is discussed. The potential of these EOs as ecofriendly and economical biocontrol in agriculture is reported. 相似文献
88.
This study was aimed to analyze factors that affect farmers' choice for major actors of veterinary service providers in village areas of Kaski district of Nepal, with the objective of identifying choice-specific attributes which could be addressed for improving the penetration of professional veterinary services in village areas. The information was obtained from 125 farmers using a structured questionnaire. A proportional hazard model was used for data analysis because of its ability to accommodate the attributes of both the chooser and the choice simultaneously. The results showed that village animal health workers (VAHWs) were the most preferred service providers followed by veterinarians and mid-level technicians. The farmers' age and education level had a significant but inverse relationship with the probability of choosing any of the three service providers. From our study, we found that the main choice-specific attributes with a significant impact on the choice probability was the distance to the preferred service provider. Since there was a high preference for VAHW, this suggests the possibility of poorly trained service providers dominating veterinary service market in village areas of Kaski district. Hence, the efforts put forward in the legalization of VAHW system in Nepal should first address the constraints that obstruct the accessibility of professional veterinary service providers in village areas. 相似文献
89.
Redding L Chetri DK Lamichhane DK Chay Y Aldinger L Ferguson J 《Tropical animal health and production》2012,44(7):1605-1613
The aim of this study was to describe animal production on small farms in the Kaski district of Nepal, with the goal of identifying areas where animal health and productivity could be improved. Eighty-five randomly selected farms from four different Village Development Committees were visited. Farmers were interviewed and premises and animals visually inspected on all farms. Feed samples were collected from a subset of farms. The most commonly kept species were water buffalo (used for milk and meat), cattle (used for milk and labor), and goats (used for meat). Average milk production levels were 4.7?kg/day for water buffalo and 1.9?kg/day for cattle. All animals were milked manually, no calves were weaned, and only one farm practiced artificial insemination. A majority of cattle and goats had access to pasture, and a majority of farms fed their working or producing animals concentrates; however, nutritional input was insufficient in terms of energy, protein, and micronutrient content to increase levels of production. Goat-raising was the most profitable endeavor, followed by water buffalo and cattle. We conclude that animals have the potential to contribute significantly to improved livelihoods of farmers in terms of both income generation and non-tangible benefits. However, we found that significant constraints on animal production exist, including insufficient nutritional levels and a lack of preventative care resulting in animal disease. Furthermore, cultural considerations reflecting attitudes toward cattle shape farming in ways that may limit production. Nevertheless, targeted interventions that improve animal health and productivity are possible without being cost prohibitive. 相似文献
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