排序方式： 共有28条查询结果，搜索用时 15 毫秒
21.
Sepul K. Barua Jari Kuuluvainen Jani Laturi Jussi Uusivuori 《European Journal of Forest Research》2010,129(2):163-172
The effects of profit and land value tax on harvesting decisions of nonindustrial private forest owners are investigated. We use a model of a utility-maximizing forest owner with amenity preferences for timber, which extends the basic two-period harvesting model to include both thinning and clear-cutting harvests. It is demonstrated that with no amenity preference, the profit and land value taxes are neutral to clear-cutting and thinning decisions. Under small to medium amenity preferences, the profit tax decreases the optimal clear-cutting volumes. However, the effect on thinning may be positive or negative, depending on the amenity preference level. The total effect of the profit tax on the short-run timber supply is negative. The effects of the land value tax contrast with those of the profit tax. Also, a tax regime with a lowered profit tax rate combined with a land value tax is analysed. It is shown to be able to bring Pareto-improvement to a regime that uses a higher profit tax but no land value tax. 相似文献
22.
孟加拉东南部土壤中的砷含量很高,不仅威胁人的健康,而且对土壤也有破坏作用。云南石梓(Gmelina arborea)在孟加拉是个快速生长的树种,也是含砷土壤中的潜力树种。研究评价了含砷试验土中丛枝菌根真菌对云南石梓(Gmelina arborea)生长的影响。播种前,四种不同浓度的砷(10mg·kg-1、25mg·kg-1、50mg·kg-1和100mg·kg-1)被加入到试验土中。记录生长参数,如,植物的根、苗鲜重、干重、冠幅径、根长和苗高、根瘤菌和孢子菌群落。菌根植株较非菌根植株生长好。与其它含砷量高的土壤中植株的生长情况相比,在含砷量为10-mg·kg-1的土壤中,菌根植株和菌根生长效果最佳,菌根植株生物量最高。随着砷浓度的增加,种苗生长,根瘤菌和孢子菌群落均明显降低p0.05)。与非菌根植株比较,菌根植株高生长增加了40%,生物量增加了2.4倍。研究表明,根瘤菌接种可以减少有害土壤中的云南石梓(Gmelina arborea)的初生长的影响。 相似文献
23.
The effects of four concentrations (0.5, 1, 5 and 10 μg mL?1) of the heavy metals Hg, As, Pb, Cu, Cd, and Cr on some senescence variables of Cuscuta reflexa Roxb. were studied. All of the treatments, except 0.5 μg mL?1, decreased Hill reaction activity, chlorophyll and protein contents and dry matter percentage in biomass and increased tissue permeability over control data. The harmful effects of the metals were best visible at 10 μg mL?1. The general order of sensitivity was As > Cd > Pb > Hg > Cu > Cr (absolute metal concentration). The data suggest that Cuscuta reflexa shows tolerance to the heavy metals tested up to 0.5 μg mL?1. 相似文献
24.
Bera BC Shanmugasundaram K Barua S Venkatesan G Virmani N Riyesh T Gulati BR Bhanuprakash V Vaid RK Kakker NK Malik P Bansal M Gadvi S Singh RV Yadav V Sardarilal Nagarajan G Balamurugan V Hosamani M Pathak KM Singh RK 《Veterinary microbiology》2011,152(1-2):29-38
This study reports the first conclusive evidence of zoonotic camelpox virus (CMLV) infection in humans associated with outbreaks in dromedarian camels (Camelus dromedaries) in northwest region of India during 2009. CMLV infection is usually restricted to camels and causes localised skin lesions but occasionally leads to generalised form of disease. However, the present outbreak involved camel handlers and attendants with clinical manifestations such as papules, vesicles, ulceration and finally scabs over fingers and hands. In camels, the pock-like lesions were distributed over the hairless parts of the body. On the basis of clinical and epidemiological features coupled with serological tests and molecular characterization of the causative agent, CMLV zoonosis was confirmed in three human cases. Clinical samples such as skin scabs/swabs and blood collected from affected animals and humans were analysed initially, for the presence of CMLV-specific antigen and antibodies by counter immunoelectrophoresis (CIE); serum neutralization test (SNT); plaque-reduction neutralization test (PRNT) and indirect immunoperoxidase test which was later confirmed by amplification of CMLV-specific ankyrin repeat protein (C18L) gene. Virus isolation was successful only from samples collected from camels. Further, sequence analyses based on three full-length envelope protein genes (A27L, H3L and D8L) revealed 95.2-99.8% and 93.1-99.3% homology with other Orthopoxviruses at nucleotide and amino acid levels, respectively. Phylogram of the three genes revealed a close relationship of CMLV with Variola virus (VARV). Considering the emerging and re-emerging nature of the virus, its genetic relatedness to VARV, zoonotic potential and productivity losses in camels; the control measures are imperative in curtailing economic and public health impact of the disease. This is the first instance of laboratory confirmed camelpox zoonosis in India. 相似文献
25.
The impacts of tree and horticultural plantations, and grassland on soil characteristics in the degraded hills of Chittagong District, Bangladesh are reported on this paper. The carbon sequestration potential and the present value of carbon revenue flow were also estimated for the degraded hills of Chittagong using A. auriculiformis plantations for the purpose. The results showed that the change of land use from degraded hill to vegetation cover had altered the physico‐chemical characteristics of soil in the study area. The organic carbon concentration and storage under vegetated land uses were significantly (p < 0·05) higher than those in the degraded hill areas. The results also showed that about 17 million megagram carbon (MgC) could be sequestered in the degraded hill areas of Chittagong District by planting A. auriculiformis trees in a 15‐year rotation. The present value of revenue flow generated by this sequestration at the current international market carbon price and assuming a realistic market interest rate could be as high as US$ 326 million. The net present value of the revenue stream is expected to be positive. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
26.
Islam S. S. Khan M. J. Bhuiyan A. K. F. H. Islam M. N. Barua S. 《Tropical animal health and production》2010,42(7):1505-1511
The objective of the study was to observe the effect of protein density of concentrate mixture on the growth performance of
Red Chittagong Cattle (RCC) heifers (Bos indicus), an endangered variety in Bangladesh. The experiment was conducted for a period of 90 days with 12 RCC heifers, and the
animals were divided into four groups on the basis of their initial live weight. The animals were assigned at random to four
dietary treatments having three replications in each in a randomized complete block design. Three iso-energetic [10.5 MJ metabolizable
energy (ME)/kg dry matter (DM)] concentrate mixtures were formulated to provide protein concentrations (%) of 15, 20, and
25 for T1, T2, and T3, respectively. Crude protein (CP) content of control diet was 7.08%. Animals of all groups were fed urea molasses straw (UMS)
ad libitum and green grass at a rate of 20% of total DM intake. Digestibility of DM was highest in the treatment group fed
25% CP supplement (T3) and lowest in the unsupplemented group (T0). Average daily gain increased with increasing CP concentration in supplements, but mean difference was not significant between
the 20% and 25% CP groups. Feed cost per kilogram live weight gain was lowest (P > 0.05) in 20% CP supplement and highest in the unsupplemented group. The results revealed that the CP concentration of 20%
in concentrate mixture containing 10.5 MJ ME is cost effective with the UMS-based diet of RCC heifers for better nutrient
digestibility and growth. 相似文献
27.
28.
Tomato leaf curl disease is a severe threat to tomato production. Yield losses are generally high in the absence of effective management strategies. The disease is caused by tomato leaf curl virus (ToLCV) and is transmitted by a whitefly vector that is challenging to control. Resistance to ToLCV is absent from most cultivated tomato gene pools, although the use of resistant cultivars would provide a better control option than minimizing the vector population. Unfortunately, resistance sources based on field screening break down when virus pressure is severe. Our previous screening and virus testing of 40 tomato genotypes led to the identification of a highly resistant genotype, Solanum pimpinellifolium AAU2019, as a new source of resistance. In this study, we investigated the inheritance and genetics of resistance to ToLCV in the cross of Pusa Ruby × S. pimpinellifolium AAU2019 in F2 and BC1Ps populations, revealing a monogenic recessive gene (best-fit ratios of resistance: susceptible to be 1:3 and 0:1) responsible for ToLCV resistance in S. pimpinellifolium AAU2019. Hence, S. pimpinellifolium AAU2019 could be considered as a potential donor parent in breeding programmes to develop tomato cultivars with resistance to ToLCV. 相似文献