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1.
Heterodera glycines is not known to occur in South-east Asian countries except in Indonesia. Specific surveys carried out recently in central India indicate absence of the nematode. The region has a large area under cultivation of soybean, and also other crop and wild hosts. H. glycines causes annual yield losses of about half a million metric tons in 10 major soybean-growing countries. Asia has to import half its demand of soybeans, mainly from North America and Brazil, where H. glycines occurs. Spread is mainly through soil mixed with seeds, or by spillage of grain. A preliminary pest risk analysis suggests that the South-east Asian region is suitable for the introduction and spread of H. glycines . Management practices are suggested to delay its introduction. 相似文献
2.
Rajan 《EPPO Bulletin》2006,36(1):59-64
Surveillance of pests is an important activity for (a) early detection and prevention of spread of indigenous and exotic pests, (b) delimiting pest distribution, (c) searching for pest free areas for meeting the requirements of national and international trade and (d) to achieve effective management of pests that affect crop production. Recent developments on these topics are reviewed with special reference to plant parasitic nematodes in India. 相似文献
3.
Effect of tillage and mode of straw mulch application on soil erosion in the submontaneous tract of Punjab, India 总被引:6,自引:0,他引:6
The submontaneous tract of Punjab comprising 10% of the state, is prone to soil erosion by water. Soils of the area are coarse in texture, low in organic matter and poor in fertility. High intensity rains during the monsoon season result in fertile topsoil removal. There is an urgent need to control soil erosion in this region so as to improve soil productivity. A field study was conducted to estimate the effect of tillage and different modes of mulch application on soil erosion losses. Treatments comprised two levels of tillage, viz. minimum (Tm) and conventional (Tc) in the main plots and five modes of straw mulch application, viz. mulch spread over whole plot (Mw), mulch spread on lower one-third of plot (M1/3), mulch applied in strips (Ms), vertical mulching (Mv) and unmulched control (Mo), in subplots in a replicated split plot design. Rate of mulch application was 6 t ha−1 in all modes. Compared with Mo, Mw reduced runoff by 33%. Runoff and soil loss were 5 and 40% higher under Tc than under Tm. Though other modes of straw mulch application (M1/3, Ms and Mv) controlled soil loss better than Mo, their effectiveness was less than Mw. Tm was more effective in conserving soil moisture than Tc. Compared with Mo, Mw had 3–7% higher soil moisture content in the 0–30 cm soil depth under Tm. Minimum soil temperature of the surface layer was 1.4–2.4 °C lower under Mw than under Mo. Straw mulching reduced maximum soil temperature and helped in conserving soil moisture. Minimum tillage coupled with Mw was highly effective in reducing soil erosion losses, decreasing soil temperature and increasing moisture content by providing maximum surface cover. 相似文献
4.
Rina D. Koyani Isha M. Bhatt Hiral R. Patel Ajit M. Vasava 《Wood material science & engineering》2016,11(1):46-56
Lignin biodegradation potential of Schizophyllum commune Fr. is studied by using sound wood blocks of Ailanthus excelsa, Azadirachta indica, Tectona grandis, Eucalyptus sp. and Leucaena leucocephala. Initially, in vitro wood decay test showed minor weight loss, but it became rapid after one month. After 120 days of incubation, weight loss was minimum in T. grandis (24.05%) whereas it was maximum in A. excelsa (34.44%). Treated test blocks were characterised by enlargement of pits on ray cell wall, formation of additional boreholes in rays, separation of fibres and cell wall thinning and formation of ‘U’-shape notches. Fungal hyphae moved through the xylem cell lumen, and intercellular spaces formed in response to separation of fibres. Hyphae traverse in adjacent cell through the cell wall pits or by making additional boreholes. In all the species studied, xylem fibres and parenchyma (axial and ray) cells were more susceptible while vessels were resistant to fungal attack. In advanced stage of decay, fibres and axial parenchyma lost their rigidity while vessel walls showed uneven thinning. In the tension wood, G-fibres remained unaffected initially but loosening and separation of gelatinous layer facilitated fungal action and showed similar pattern of cell wall deterioration. Among the wood of different species studied, Tectona was more resistant whereas Ailanthus was more susceptible to fungal attack. 相似文献
5.
The allelopathic effects of Adina cordifolia, Alnus nepalensis, Celtis australis and Prunus cerasoides were tested by growing crops of Eleusine coracana, Glycine max and Hordeum vulgare on top soil, rhizosphere soil from the plantation of these trees, and on field soil either mulched with dry leaves or irrigated with aqueous leaf extracts of the agroforestry tree species. Germination percentage, shoot length, root length and dry matter production and pigment contents of crops were depressed by agroforestry tree crops. Maximum reduction in germination percentage, root-shoot length and dry matter production was obtained with experimental garden soil mulched with dry leaves of trees and by the effect of Adina cordifolia followed by P. cerasoides, H. vulgare proved most susceptible and E. coracana highly resistant to these tree-top interactions. 相似文献
6.
Fleischer RL Price PB Walker RM Filz RC Fukui K Friedlander MW Holeman E Rajan RS Tamhane AS 《Science (New York, N.Y.)》1967,155(3759):187-189
Cosmic ray nuclei have been observed with the use of plastic trackdetecting solids in satellites and high-altitude balloon flights. Nuclear emulsions in the stacks of plastic sheets allowed the positive identification of cosmic raynuclei as light as nitrogen. The most striking new information was the failure to observe relativistic iron nuclei, a result which has led to an advance in the understanding of track registration criteria. 相似文献
7.
Anjana Srivastava Kailash Singh Rawat Santosh Chandra Bhatt Deepa Rawat Prakash Chandra Srivastava 《Communications in Soil Science and Plant Analysis》2016,47(17):1961-1966
The aim of the study was to evaluate the degradation and persistence of 2-amino 4-chloro 6-methyl pyrimidine (AM), nitrification inhibitor at 1 and 2 µg g?1 application rates in soil. The extraction of AM was done by QuEChER’s (Quick, Easy. Cheap. Rugged and Safe) method and the quantitative analysis by high-performance liquid chromatography (HPLC). AM decreased with time at both the levels of application with the decline being faster in the beginning up to 7 d. Dissipation of AM occurred in a single phase with the persistence data fitting well to the first-order kinetics. Half-lives of AM were determined to be 14.33 and 16.7 d at 1 and 2 µg g–1 levels application rates. Since AM remains effective for an adequate period of time, it can be used for increasing efficiency of nitrogenous fertilizers in rice–wheat cropping systems as well as a safeguard for controlling environmental pollution in subtropical soils. 相似文献
8.
Two lactational intramammary antibiotic preparations (cloxacillin and oxytetracycline) were each used to treat eight goats by intramammary infusion in one half. The rate of release of the antibiotics was monitored by a diffusion assay based on the sensitive organism Bacillus stearothermophilus var. calidolactis. Cloxacillin was still detectable 156 hours after the final treatment while oxytetracycline was undetectable 108 hours following treatment. A small but significant amount of antibiotic was translocated between treated and untreated halves of the udder in both cases. 相似文献
9.
Summary Variation in pigment content of the flour of bread wheats (Triticum aestivum L.) was studied in the progenies of F1 and F2 of three crosses and their reciprocals. Reciprocal differences in pigment content were observed in the F1 and F2 means. Low pigment content was found to be partially dominant or over dominant in the crosses studied. There was evidence of substantial mid-parent F1 heterosis in all crosses and betterparent F1 heterosis in three crosses. In the F2, heritability estimates were moderate to high. The F2 frequency distributions were not normal. Estimation of effective factor pairs indicated the presence of one or two major gene pairs involved in the expression of pigment content in the flour. Action of modifiers was also assumed in one cross and its reciprocal. A factorial approach to metrical character suggested that the F2 segregation ratios of low pigment content to high pigment content were 3:1, 15:1, 13:3 and 9:7 for the different crosses. Utilization of the findings in a wheat breeding program is briefly discussed. 相似文献
10.
Influence of fibrolytic enzymes on the hydrolysis and fermentation of pure cellulose and xylan by mixed ruminal microorganisms in vitro 总被引:3,自引:0,他引:3
Colombatto D Mould FL Bhatt MK Morgavi DP Beauchemin KA Owen E 《Journal of animal science》2003,81(4):1040-1050
A series of in vitro studies was conducted to determine the effects of adding a commercial enzyme product on the hydrolysis and fermentation of cellulose, xylan, and a mixture (1:1 wt/wt) of both. The enzyme product (Liquicell 2500, Specialty Enzymes and Biochemicals, Fresno, CA) was derived from Trichoderma reesei and contained mainly xylanase and cellulase activities. Addition of enzyme (0.5, 2.55 and 5.1 microL/g of DM) in the absence of ruminal fluid increased (P < 0.001) the release of reducing sugars from xylan and the mixture after 20 h of incubation at 20 degrees C. Incubations with ruminal fluid showed that enzyme (0.5 and 2.55 microL/g of DM) increased (P < 0.05) the initial (up to 6 h) xylanase, endoglucanase, and beta-D-glucosidase activities in the liquid fraction by an average of 85%. Xylanase and endoglucanase activities in the solid fraction also were increased (P < 0.05) by enzyme addition, indicating an increase in fibrolytic activity due to ruminal microbes. Gas production over 96 h of incubation was determined using a gas pressure measurement technique. Incremental levels of enzyme increased (P < 0.05) the rate of gas production of all substrates, suggesting that fermentation of cellulose and xylan was enzyme-limited. However, adding the enzyme at levels higher than 2.55 microL/g of DM failed to further increase the rate of gas production, indicating that the maximal level of stimulation was already achieved at lower enzyme concentrations. It was concluded that enzymes enhanced the fermentation of cellulose and xylan by a combination of pre- and postincubation effects (i.e., an increase in the release of reducing sugars during the pretreatment phase and an increase in the hydrolytic activity of the liquid and solid fractions of the ruminal fluid), which was reflected in a higher rate of fermentation. 相似文献