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121.
Genetic Resources and Crop Evolution - The genetic architecture of oil content, seed yield and its related biometric traits in castor was investigated through generation mean analysis in four...  相似文献   
122.
Smallholder farmers dominate agriculture in Nepal. These farmers have poor knowledge about agriculture and lack of support for soil management and integrated plant-nutrient systems. Focusing on the importance and need for soil-fertility management, a soil-testing mobile van program has recently been introduced in Nepal by Soil Management Directorate, Hariharbhawan. With the introduction of the mobile lab, famers can get their soil tested for nutrient deficiencies and fertilizer requirements at their doorsteps. Using mobile lab, spatial distributions of chemical properties, including pH, organic matter (OM), total nitrogen (N), available phosphorus (as P2O5), and available potassium (as K2O) were examined in soil samples taken from the 0 to 15 cm depth from selected agricultural fields in eight different districts in the mid-hills and Terai regions of Nepal. Tests conducted on 1,479 soil samples in the soil-testing mobile van revealed the following: the mean soil OM ranged from 0.01 to 1.77%; total N content ranged from 0.01 to 0.08%; mean available P2O5 ranged from 16.47 to 197.82 kg ha?1; and mean available K2O ranged from 84.3 to 422.57 kg ha?1. For each crop to be grown, farmers were provided with individual soil health reports and fertilizer recommendations (rate, amount, and type). This program not only allows scientists and farmers to work closely and share information but also serves as a model for the nation to successfully transfer technology for improving soil health and sustainability.  相似文献   
123.
Nemarioc-AL and Nemafric-BL phytonematicides consistently reduced populations of plant-parasitic nematodes. The contribution of juvenile hatch inhibition to the overall reduction of the nematode numbers by the two phytonematicides, with cucurbitacin A and B as active ingredients, respectively, remains undocumented. The objectives of this study were to examine (i) the response of Meloidogyne incognita second-stage juveniles (J2) hatch to increasing concentration of cucurbitacins A and B, (ii) the potential saturation of J2 hatch when exposed to cucurbitacins for extended incubation periods, (iii) the minimum inhibition concentration for J2 hatch and (iv) the reversibility of J2 hatch inhibition.. Eggs of M. incognita were exposed to a series of purified cucurbitacin A and B concentrations over five incubation periods of 24, 48, 72?h and extended incubation periods of 7 and 10 days. Methanol-dissolved cucurbitacin A and B were each diluted and pipetted into well-plates making 11 concentrations, ranging from 0.0 to 2.5 µg.ml?1 water solvent. Juvenile counts were made after 24, 48 and 72?h, with those for saturation assessed at 7 and 10 days. Thereafter, treatments were diluted five times, incubated again for 5 days and counted to establish reversibility of J2 hatch inhibition. In all incubation periods, treatment effects were highly significant (P?≤?0.01), with J2 hatch and cucurbitacin concentrations exhibiting quadratic relations. Minimum inhibition concentrations of the two cucurbitacins were between 1.13 and 1.40?µg.ml?1. Treatment effects for reversibility to J2 hatch inhibition were not significant (P?>?0.05). In conclusion, J2 hatch inhibition could be one of the waysthrough which the two phytonematicides reduced population densities of Meloidogyne species.  相似文献   
124.
Breeding wheat for resistance to Heterodera avenae in southern Australia has been in progress for nearly 30 years and recently a number of resistant varieties have been released. Early breeding work was hampered by three factors: • a lack of appreciation of the role and extent of the problem, • inaccurate, slow screening methods, ultimately being replaced by the 'tube' test and soon by linked molecular markers, • inappropriate breeding strategies, so that varietal releases have taken place only when the breeding has been fully integrated into the main programs. The experiences in southern Australia will be relevant to many other areas in the world where H. avenae is the major pest. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   
125.
Thiabendazole insensitive strains ofHelminthosporium solani, the causal agent of silver scurf, make controlling the disease with seed treatment difficult. Potato tuber seed treatments and environmental storage management practices were investigated as means to minimize silver scurf. Fungicide seed treatments were evaluated for control ofH. solani; disease was evaluated during the growing season, at harvest, and after 5 months of storage. Silver scurf was observed on progeny tubers eleven weeks after planting. Fungicides that reduced silver scurf incidence and severity on the seed resulted in reduced incidence and severity of the disease in the progeny tubers at harvest and significantly lower disease ratings after storage. Only small increases in disease incidence (0-8%) were seen after storage. Thiophanate-methyl with mancozeb, Captan with mancozeb, and fludioxonil were among the most effective in reducing the incidence and severity of silver scurf on seed and in progeny tubers (Incidence on progeny tubers at harvest for these three treatments were 3%, 9%, and 8% respectively). Thiophanatemethyl alone was not effective for control of silver scurf (48% incidence compared to 43% incidence for the untreated control). Environmental conditions in storage affected disease development. Reduced humidity (85%) during the curing period (0–3 weeks after harvest) significantly reduced (11%) the surface area of tubers infected with silver scurf. Free moisture on the tuber surfaces during storage significantly increased (15%) tuber surface area infection.H. solani was shown to survive in soil and on some potato storage building materials for up to 9 months. The silver scurf disease of potatoes can be suppressed using effective seed treatment and storage management.  相似文献   
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127.
The effects of combinations of plant‐derived molluscicides with piperonyl butoxide (PB) or ENT 8184 (MGK‐264) were studied on different enzyme activities and biogenic amine levels in the nervous tissue of Limnaea acuminata. 24‐h in vivo exposure of the nervous tissue of L acuminata to 40% and 80% of the 24‐h LC50 of the plant‐derived molluscicides Azadirachta indica oil, Allium sativum powder and oleoresin of Zingiber officinale rhizome and their active molluscicidal components azadirachtin, allicin and [6]‐gingerol, alone or in combination (1 + 5) with PB or ENT 8184, caused a significant reduction in the activity of acetylcholinesterase, lactic dehydrogenase, acid and alkaline phosphatases and sodium‐potassium ATPase. There was a significant increase in the activity of succinic dehydrogenase. In vivo exposure for 24 h to sub‐lethal concentrations of azadirachtin, allicin and [6]‐gingerol, singly and with PB or ENT 8184, significantly altered the dopamine and 5‐hydroxytryptamine levels in the nervous tissue of L acuminata. It is concluded that these active moieties singly or with PB or ENT 8184 adversely affect all known neurotransmission mechanisms in the snail, either separately or through a complex interaction between the different neurotransmitters. © 2000 Society of Chemical Industry  相似文献   
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