喜马拉雅山西侧山岭森林的生物量密度、利用和生产动态(英文)

证据显示印度喜马偕尔北部的喜马拉雅州森林生物量大量减少。政府通过局部测定核查了森林生物量减少情况。本文以树木生物量来衡量森林退化,评估了主要用地类型内森林生物量的现状,检查了森林可持续性。结果表明,保育林分树木地上部最大生物量平均为1158t·hm-2,保护林、休耕地、耕作非灌溉地、草地、果园和耕地灌溉地的平均生物量依次是728,13,11,8,5和3t·hm-2。当地农民用于烧柴、马料或其他用途的树木生物量仅占可获得的生物总量的0.31%。现在的取用水平只能在短期内维持森林可持续性,从长期来看森林再生不足。采用对数生长模型对未来30年的森林生物量进行料模拟,并通过敏感性分析对影响系统行为的输入变量的相对显著性进行了分析。拟合模型强调了未来的森林资源降低不可避免。政府部门应该积极响应,出台相应政策才能有效地保护森林资源。     

Evolving strategies for crop planning and operation of irrigation reservoir system using multi-objective differential evolution

In this paper multi-objective differential evolution (MODE) approach is proposed for the simultaneous evolution of optimal cropping pattern and operation policies for a multi-crop irrigation reservoir system. In general, farming community wants to maximize total net benefits by irrigating high economic value crops over larger area, which may also include water-intensive crops and longer duration crops. This poses a serious problem under water-scarce conditions and often results in crop failure. Under varying hydrological conditions, the fixed cropping pattern with conventional operating rule curve policies may not yield economically good results. To provide flexible policies, a nonlinear multi-objective optimization model is formulated. To achieve robust performance by handling interdependent relationships among the decision variables of the model, the recent MODE technique is adopted to solve the multi-objective problem. The developed model is applied for ten-daily reservoir operation to a case study in India. The model results suggest that changes in the hydrologic conditions over a season have considerable impact on the cropping pattern and net benefits from the irrigation system. Towards this purpose, the proposed MODE model can be used to evolve different strategies for irrigation planning and reservoir operation policies, and to select the best possible solution appropriate to the forecasted hydrologic condition.     

The Upland Settlement Project of Bangladesh as a Means of Reducing Land Degradation and Improving Rural Livelihoods

Because of illegal logging, increased population pressure and intensified shifting cultivation, forest coverage of the Chittagong Hill Tracts (CHT) has decreased drastically resulting in land degradation. Many development projects have been implemented to combat forest loss and land degradation and also to improve the livelihoods of the hill people. This paper reports an empirical study of the Upland Settlement Project (USP) of Bangladesh which was undertaken to prevent land degradation and enhance the standard of living of the people. Planters were found to have given up shifting cultivation and adopted soil conserving agroforestry practices, and forest coverage has been increased in the project village. Interacting with project staff members, government officials and NGOs assisted planters in diversifying livelihood strategies thereby reducing dependency on project resources. Rich planters, utilizing their own capacity, expanded their income sources successfully. Poor planters still remain wage labourers because they do not have sufficient finance and networks to invest in productive ventures. Planters’ participation in project activities and the information flow between them and project staff were found to be minimal. Suggestions are made for the continuity of project functions, which involve greater participation of planters in rubber management functions, improved information flow, resolution of land tenure and greater equality in distribution of rubber revenue.

Top‐cross vs. poly‐cross as alternative to test‐cross for estimating the general combining ability in potato

Test‐crosses for estimating combining ability in potato although useful are difficult to make being labour intensive and time consuming, and due to the problem of sterility. The objective of the present study was to test methods for estimating general combining ability (GCA) of parents based on fewer matings. The GCA of 12 females estimated based on matings with specific single testers (top‐cross) and three types of bulk pollen (poly‐cross) were compared with those estimated by 72 (12 × 6) test‐crosses, using common testers in three types of matings. The study was conducted for 2 years at each of the two locations representing short‐days subtropical conditions in plains and long‐days temperate conditions in hills of India. Analysis of variance of test‐crosses showed that both general and specific combining ability effects were important for tuber yield, late blight resistance as well as general impression, the characters studied. Correlation coefficients among three types of matings showed that bulk pollen matings had poor effectiveness in predicting the GCA of the females, whereas matings with selected individual testers resulted in GCA estimates similar to those based on six testers. Thus use of top‐cross involving selected tester could substantially reduce the number of matings required for estimating the GCA. Among the six testers used, the tester CFK69.1 could estimate the GCA of the females with reasonably high accuracy both for tuber yield and general impression, and ‘Tobique’ for reaction to late blight.     

Influence of abiotic factors on behaviour and adult emergence pattern of coconut white grub, <Emphasis Type="Italic">Leucopholis coneophora</Emphasis> Burmeister (Coleoptera: Scarabaeidae)

Leucopholis coneophora Burmeister is a subterranean pest associated with coconut based cropping systems in south India. Feeding damage causes yellowing of fronds and yield reduction. To develop appropriate IPM strategy a basic knowledge on insect behaviour is essential. Four years studies indicated that, adult emergence of L. coneophora was commenced with summer shower in April in Kerala. Delay in summer shower delayed the emergence. After a pause in May, the emergence resumed with the setting of south west monsoon in June. The beetles did not emerge during dry spells in between the rainy days, when the soil temperature (at 10 cm depth) was ≥34.5 °C. Emergence of the beetles started at an illuminance of 124.37?±?75.5 l in evening and remained active till 2?±?0.4 l with a maximum swarming at 32.6?±?15.1 l. Female emergence and mating occurred at 12.04?±?8.1 l. Female based sex pheromone mediated communication is evident. Strong competition among the males for mating with emerging female, which was evident by a wider operational sex ratio in the initial period (1:10.11) that narrowed down to 1:4.33 in later days. The beetles neither congregate on any host plant nor exhibit phototaxis. Number of beetles entrapped in light traps varied from 1.5–16.5% and hand picking is highly significant over light trapping. Hence hand picking of beetles daily in the evening for 2 weeks commencing from the onset of south west monsoon in Kerala, in Indian subcontinent is suggested as a tool in IPM.     

The genus <Emphasis Type="Italic">Luteovirus</Emphasis> from infection to disease

Luteoviruses are economically important plant viruses. Specifically, barley yellow dwarf virus is epiphytotic to almost all small-grain cereal growing areas. The disease cycle is complex. This luteovirus has evolved several intelligent mechanisms to communicate with both plant and phloem-feeding insect-vector aphid. Environmental cues influence disease severity, aphid infestation and viral load. Within an aphid, virus circulates persistently in a non-propagative manner and is transmitted selectively to the host plants. Selection of viruses within aphids has a role in virus isolate prevalence over a specific area. In the host-plant system, the virus has to release its single sense-strand RNA genome (approx. 5.6 to 6 kb), translate and subsequently replicate its genome using its own replicase and host machinery. This review summarizes our current understanding of disease epidemiology and reviews the current literature encompassing viral infectivity, economic impact and control measures.     

Evaluation of multi-nutrient extractants for determination of available P,K, and micronutrient cations in soil

Sixty soil samples (0–0.15 m depth) collected randomly from different districts of Himachal Pradesh were used to evaluate ammonium bicarbonate-diethylenetriaminepenta acetic acid (AB-DTPA) and acid ammonium acetate-ethylene diamine tetra acetic acid (AAAc-EDTA) over standard methods for P, K, and micronutrient cations. Among Olsen P, Bray P1, AB-DTPA P, and AAAc-EDTA P, available P (kg ha^?1) varied from 7.8 to 44.3, 9.5 to 61.1, 6.5 to 38.8, 10.5 to 52.1; available K (kg ha^?1) among NH4OAc, AB-DTPA, and AAAc-EDTA ranged from 103.6 to 372.3, 86.6 to 364.9, and 74.6 to 362.5. In case of micronutrients cations, AB-DTPA in general, extracted more amounts as compared to DTPA alone. AAAc-EDTA correlated highly with the Olsen P. AB-DTPA-K and AAAc-EDTA-K correlated well with standard method (NH4OAc) however; AAAc-EDTA had higher correlation with AB-DTPA for K extractability. Among methods for micronutrients highest significant correlations were observed between AB-DTPA and DTPA for Cu, Fe, and Zn.