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在孟加拉吉大港丘陵地区,调查了热带季风气候条件下的3种人工林(7年生大叶相思(Acacia auriculiformis)林、15年生大叶相思林和18年生混交林)和1种天然林的森林凋落物及其对土壤性质的作用.结果表明,总的有机质积累随人工林树龄增加而增加,但是年积累量随之降低.在同一植被类型内,不同坡位新鲜或部分分解的凋落物有机质累计量变化较大,坡底部有机质积累量最高,沿着山坡向上逐渐减少.在15年生大叶相思人工林内,土壤整合有机物积累量变化趋势与新鲜或部分分解有机质积累量变化趋势相反.在7年生和15年生的大叶相思林以及18年龄的阔叶混交人工林内,新鲜、部分分解和完全分解(含土壤整合有机质)有机质总生产速率分别是2554.31、705.79和1028.01kg.ha-1·a-1,新鲜凋落物有机质在3种林分中的生产速率分别是38.23,19.40和30.48 kg·ha-1·a-1.3种人工林和自然林内,平均新鲜凋落物的有机质积累占有机质产出总量的32.45%,部分分解凋落物占13.50%,而全分解整合土壤有机质占54.56%.森林土壤酸度随凋落物分解阶段的深入而增加. 相似文献
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Debnath SC Kundu A Das SK Mandal TK Bhattacharyya A Choudhury A Chakraborty AK 《Journal of agricultural and food chemistry》2003,51(20):5977-5984
Toxicokinetic behavior and metabolism studies of metamitron and its effect on the cytochrome P(450) content of liver microsomal pellet were carried out in black Bengal goats after a single oral administration at 278 mg kg(-1) and consecutive oral administration of 30 mg kg(-1) for 7 days. Metamitron was detected in the blood sample at 0.08 h (12.0 +/- 0.87 microg mL(-1)), maximum at 4 h (84.3 +/- 8.60 microg mL(-1)) and minimum (14.6 +/- 1.67 microg mL(-1)) at 36 h blood sample after a single oral administration. The absorption rate constant was 0.69 +/- 0.09 h(-1). The Vd(area) (2.00 +/- 0.08 L kg(-1)) and t(1/2)beta (8.98 +/- 0.70 h) values suggested wide distribution and long persistence of the compound in the body. The values of T approximately B (0.80 +/- 0.04), F(c) (0.55 +/- 0.01), Cl(B) (0.15 +/- 0.00 L kg(-1) h(-1)), and K(21) (0.41 +/- 0.03 h(-1)) suggested that metamitron retained in the blood compared to that in the tissue. Maximum concentration of metamitron residue was found in the adrenal gland followed by bile on day 4 of single oral administration. The higher Cl(R) compared to Cl(H) value indicated the excretion of the major portion (34-40%) through urine compared to feces (20-26%). Maximum concentrations of metamitron and its metabolite, deaminometamitron, were excreted through urine and feces at 48 and 24 h samples, respectively. The recovery of metamitron including its metabolite in terms of parent compound varied from 69.3 to 80.1%, of which contribution of metabolite in terms of parent compound varied from 53.1 to 63.0%. Repeated oral administration of metamitron at 30 mg kg(-1) for 7 days caused induction of the cytochrome P(450) content of liver microsomal pellet of goat, suggesting oxidative deamination of metamitron. 相似文献
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Two sets of experiments were conducted to study the chemical composition, mineralization and availability of nutrients （particularly N） of Azolla biomass and cyanohacteria blooms in submerged rice soil. One set of experiment was conducted with Azolla without soil and the other with both Azolla and cyaobacteria with soil, in laboratory condition. Large samples were collected from the rice fields. The study shows that Azolla and cyanobacterial biomass contain good amounts of C, N, P and Ca. The chemical analysis of oxidizable C, total N, P and Ca showed that Azolla biomass contain 20.7% oxidizable C, which is higher than the cyanobacterial biomass （9.18%）. The N content in Azolla biomass was found to be 4.32%, than that of cyanobacterial biomass, i.e., 2.57%, however, P and Ca contents were also found to be higher in Azolla averaging to 124.83 ppm and 345.3 mg/100 g, respectively than cyanobacteria. The leachate analysis revealed that Azolla biomass release about 39.18% to 64.48% oxidizable C and about 19.23% to 33% N after 45 days of incorporation of soil dilution. Incorporation of Azolla and cyanobacterial biomass N@ 100 kg/ha significantly improved the oxidizable organic C, total as well as available N content in soil up to 75 days of incubation. Due to the incorporation of Azolla in soil, oxidizable organic C increased 25.51%, total N 4.10% and available N 47.65%. Almost similar trend of increase was also observed with the incorporation of cyanobacterial blooms. 相似文献
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We investigated the suitability of six mealybug species, namely Phenacoccus solenopsis, Saccharicoccus sacchari, Paracoccus marginatus, Drosicha mangiferae, Nipaecoccus viridis and Ferrisia virgata as hosts to Aenasius arizonensis ( = Aenasius bambawalei). The study was conducted to ascertain a viable parasitic relationship between a parasitoid species and different mealybug hosts. Successful parasitization, complete development of immature stages within the host and adult emergence was observed only in P. solenopsis, whereas, other mealybug species were not found suitable as hosts by the parasitoid in both choice and no-choice tests. The development studies of A. arizonensis on P. solenopsis showed that the mean duration from oviposition to mummy formation was 6.13 days, while, from mummy formation to adult emergence, it was 5.43 and 7.05 days for male and female, respectively. The total development period from oviposition to adult emergence was 11.28 days for males and 13.13 days for females. Female adults (19.96 days) live longer as compared to male adults (7.83 days). Among different mealybug species, P. solenopsis was observed to be the only ecological and fundamental host of A. arizonensis. 相似文献
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Shashi Bhushan Choudhary Hariom Kumar Sharma A. Anil Kumar R. T. Maruthi Pran Gobinda Karmakar 《Genetic Resources and Crop Evolution》2017,64(7):1675-1686
Understanding phyto-geographical distribution pattern and ethnobotanical applications are critical for comprehensive conservation and utilisation of native plant genetic resources. Dearth of such scientific reports on Corchorus species in India seriously compromises inclusiveness, precision and penetration of national endeavour to conserve the valuable resources. In this context, an ecogeographical study conducted to analyse geographical distribution, ecological adaptation, species richness and ethnobotanical applications of the genus in the country. The study revealed pandemic distribution of the genus with differential habitat preferences. Combine geographical, edaphic and precipitation based distribution profile of Corchorus spp. demonstrated multilayer interactions between species and environment that led to their differential spatial distribution. The highest species concentration was found in Tamil Nadu followed by Gujarat, Rajasthan, Madhya Pradesh and Maharashtra. Complementarity analysis showed that the major diversity hotspots for the genus present in Tamil Nadu and Gujarat. Besides, wide spectrum ethnobotanical applications of the genus reflect their long association with prevailing ethnic communities across regions. Documentation of such time honoured traditional practices has special bearing on designing comprehensive conservation and management strategies. This information will help to prioritise both ex-situ and in-situ conservation efforts for the genus particularly in ecologically vulnerable sites of India. 相似文献
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Solena amplexicaulis (Lam.) Gandhi (Cucurbitaceae) is a promising vegetable in Southeast Asia. Infestation of Aulacophora foveicollis Lucas (Coleoptera: Chrysomelidae) adults on leaves of the crop plant causes death of the plant and reduces crop production. Currently, growers are applying insecticides to control this pest, which are harmful to health and environment. Hence, an attempt has been made to find out allelochemicals from leaves attracting the insect, which might be used for ecofriendly pest management program. The emission of volatiles was detected from undamaged leaves of herbivore-induced plants after 24 h and 120 h of continuous females feeding on lower leaves of the same plants by GC-MS and GC-FID analysis. The insect showed attraction to systemically released volatiles from herbivore-induced plants against unharmed plants in Y-shaped glass tube olfactometer bioassays. The insect was attracted to a synthetic blend of 1.2 µg linalool oxide + 3.2 µg nonanal + 1.5 µg trans-2-nonenal dissolved in 20 µL CH2Cl2 in olfactometer and wind tunnel bioassays, and hence, this blend could be used in development of baited traps in pest management strategies. 相似文献
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Summary Soybean is an important oilseed crop in India and varieties with high yield potential are being developed since 1969. This study was conducted to assess the impact of breeding on yield and plant characteristics during the last 25 years. A 3-year field experiment was conducted to evaluate forty three soybean varieties belonging to two different selection cycles and representing most of the varieties developed in the domestic breeding programme of India from 1969 to 1993. Varieties resulting from selection cycle 1 showed 4 times higher seed yield and harvest index as compared to the farm traditional variety Kalitur. This yield increase was due to an increase in biomass, pods plant–1, mean seed weight and longer seed filling duration, but a reduced plant height and improved lodging tolerance, less seeds pod–1 and early flowering and maturity dates. The varieties of selection cycle 2 showed 19% higher seed yields and 16% increase in harvest index over selection cycle 1 accompanied by longer seed filling duration, more seeds pod–1 and reduced plant height. The annual genetic gain in seed yield of soybean varieties released in India from 1969 to 1993 was approximately 22 kg ha–1. 相似文献
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A field experiment was conducted to evaluate the response of chickpea, Cicer arietinum cv. GG 2 to cobalt sulfate and cobalt chloride at 0, 100, 200, 400, 800 and 1,600?g ha?1. At three leaf stage chickpea seedlings were fertigated with both cobalt sources and levels. Both cobalt sources at the higher level (400 to 1,600?g ha?1) were found injurious to chickpea. All growth, yield, and quality parameters were adversely affected by cobalt sulfate at every level; however, cobalt chloride has given appreciable result up to 100 and 200?g ha?1 over no application of cobalt. Cobalt content in plant and soil increased linearly with increases in cobalt concentration, which reduced chickpea yield linearly. Cobalt sulfate was apparently more harmful than cobalt chloride. The study suggests cobalt chloride has not shown any toxicity up to 100?g ha?1 and can be used for higher productivity of chickpea. 相似文献
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BACKGROUND: Thiamethoxam, a neonicotinoid insecticide, has been widely accepted for use in various crops, including vegetables, owing to its high efficacy against various chewing and sucking insect pests. In this particular study, the authors examined the residue dynamics of this insecticide in tomato and soil and calculated a safety index for this insecticide in an Indian context. RESULTS: In tomato fruits, the insecticide dissipated from 82 to 87% in 10 days with a half‐life of 4 days, whereas dissipation in soil, under tomato crop, varied between 72 and 75% in 15 days with a half‐life of 9 days. Total residues reached below detectable level in 15 days in tomato fruits and 20 days in soil. Maximum damage (30%) was found in control plots, as opposed to 8–10% of fruit damage in treated plots. One degradation product was detected on the tomato fruit surface, and three metabolites were identified in tomato fruits by the LC‐MS technique. The metabolites have been reported for the first time in tomato fruits. CONCLUSION: Thiamethoxam at normal and double the recommended use rate effectively controlled aphids, whiteflies and Helicoverpa, as the insect population decreased to a minimum within 10 days of spraying in comparison with the control. There was no significant difference between the two rates of application, and both thiamethoxam treatments significantly increased tomato fruit yield compared with the untreated control. A maximum residue limit (MRL) of 0.05 mg kg?1 for tomato has been proposed, with a corresponding preharvest interval (PHI) of 8 days. These parallel advances in toxicology and analytical chemistry have strengthened the observations that thiamethoxam can be used safely and efficiently in crop protection programmes. Copyright © 2009 Society of Chemical Industry 相似文献