放牧率和放牧时期对绵羊排粪量、采食量和干物质消化率关系的影响

实验研究表明，绵羊在同一放牧时期，随着放牧率的增大，鲜粪量有所减少，粪中干物质含量有所增大，但只有处理1．33羊／hm2·138天与6．67羊／hm2·138天问存在显著性差异。在同一放牧率条件下，不同放牧时期相比，以8月份粪中干物质含量最低；在各种处理之间，放牧绵羊全天干粪量均无显著性的差异。在同一放牧时期，随着放牧率的增大日采食量显著减少，而同一放牧率不同放牧时期的日采食量保持相对稳定。粪便的干重与干物质采食量的关系很小，与干物质消化率呈负相关。放牧绵羊白天排粪量为晚上的2倍，但粪中干物质含量几乎没有差异，同时，不同放牧率和不同放牧时期对粪便的颜色和形状等均有较明显的影响。     

Culture of Eriocheir sinensis Larvae in Ponds in Greenhouse

A total of 15 pools were selected from a greenhouse, and they were randomly and evenly divided into three groups. In each group, one stocking density of Eriocheir sinensis was arranged. The results showed that after 45-d culture, the crab number per kilogram reached about 300 with survival rate of about 20%; the initial stocking density had significantly effect on the body size of E. sinensis on sel , instead on the survival rate of E. sinensis larvae. Therefore, it is feasible to conduct the culture of E. sinensis larvae in a pool in greenhouse.     

Effects of Stocking Density on Composition and Performance of Reared Arctic Charr (Salvelinus alpinus)

Abstract

Proximate composition and performance of Arctic charr (Salvelinus alpinus) stocked at 40, 50, and 75 kg/m³, were determined. Moisture content of fish fillets decreased while their protein and lipid contents increased during the 24 weeks of rearing period. Statistical analyses indicated that moisture, protein and lipid contents of charr flesh varied significantly among density groups while ash contents did not. While the moisture and ash contents of fish fillets were directly related to stocking density (r = +0.9435 and r = +0.9918, respectively), contents of protein and lipid did not (r = ?0.5251 and r = ?0.7038, respectively). The level of carotenoids in the flesh and skin of Arctic charr increased with duration of feeding on pigmented diets. However, no correlation (r = ?0.6053) existed between stocking density and concentration of carotenoids. The specific growth rate (SGR), feed conversion ratio (FCR), and protein efficiency ratio (PER) were significantly influenced by stocking densities but the hepatosomatic index (HSI) of fish did not. These performance parameters of fish were well correlated with stocking density (r = ?0.9368, ?0.9975, ?0.9899, and ?0.9920, respectively). Although SGR, FCR and PER of fish from different stocking densities varied significantly (p < 0.05), their final weights did not.     

Direct impacts of recent climate warming on insect populations

Effects of recent climate change have already been detected in many species, and, in particular, in insects. The present paper reviews the key impacts of global warming on insect development and dispersal. The effects of climate change appear to be much more complex than a simple linear response to an average increase in temperature. They can differ between seasons and bioclimatic regions. Earlier flight periods, enhanced winter survival and acceleration of development rates are the major insect responses. Differential response of insects and hosts to warming up might also lead to disruption of their phenological synchrony, but adaptive genetic processes are likely to quickly restore this synchrony. In a number of cases, warming results in removing or relocating the barriers that limit present species' ranges. It is also likely to facilitate the establishment and spread of invasive alien species. Finally, knowledge gaps are identified and future research interests are suggested.     

The newest leafminer pest in Israel,Liriomyza huidobrensis

The pea leafminer,Liriomyza huidobrensis (Blanchard), recently introduced into Israel, has proven to be extremely proliferous and difficult to control. It is a much more serious pest of vegetable and flower crops than the previously introducedLiriomyza trifolii (Burgess). Photosynthesis is reduced and cosmetic damage is incurred when adult flies stipple plant leaves with feeding punctures and larvae mine the leaves. This paper will review briefly the history, biology and potential control measures of the pea leafminer.     

盐池沙地主要灌木种的物候及生长规律研究

本文根据实验基地的实际现测数据,阐述了柠条、毛条、杨柴、花棒、沙柳、柽柳、沙木蓼等七种沙土灌木的物候及生长规律。     

多年生观赏草的生长和繁殖特性研究

对引种的13种观赏草的物候期、生长情况、繁殖特性进行了调查研究并结合引种试验和应用调查对其引种安全性进行了评价.结果表明:13种观赏草均能够在宁波气候条件下正常生长,达到较好的景观效果,而且不存在自播和根系扩张的可能,确保了生态安全.为今后观赏草在长三角地区园林景观中的应用提供了依据.     

用随机发育模型预测马尾松毛虫的发生期

用马尾松毛虫各龄虫口密度的定期调查资料和积温资料,拟合Logistic随机发育模型,结果表明,该模型能精确地描述马尾松毛虫第1代1～6龄幼虫的发育进程。对各龄虫口的时间分布,模型预测值和观察值的吻合程度达90%。对模型参数进行比较表明,除了温度(积温)以外,还有另外一些因素影响着马尾松毛虫的发育进程。     

Pearl Millet Phenology and Growth in Relation to Thermal Time under Arid Environment

Pearl millet ( Pennisetum glaucum L.R.Br.) hybrid MH 179 was grown under two moisture regimes viz., optimal moisture and rainfed conditions. The field experiment was continued for three consecutive rainy seasons to quantify the pearl millet development with thermal time. The possible influence of variation in natural sowing date on the relationships between crop development and thermal time have been described. At cardinal temperatures of 10°C (base temperature below which pearl millet development ceases), 33°C (optimal temperature for development) and 45°C (maximum temperature at and above which no development takes place), the crop required 1490–1794°Cd thermal time to reach physiological maturity. The thermal time requirement for different developmental stages was influenced by the sowing time and moisture availability during the growing season of the crop.
The leaf tip appearance on the main shoot of pearl millet in relation to thermal time was almost linear under both moisture conditions requiring about 44–50°Cd ± 2.6 °Cd leaf⁻¹, till the appearance of the flag (last) leaf. However, leaf tip appearance on primary tillers was slightly slower and required 53-58°Cd ± 4.7°Cd for each new leaf. Appearance of first primary tiller was later (at 320°Cd after emergence) under the rainfed condition as compared to the crop under the optimal moisture (at 250°Cd).Thereafter, the tiller appearance in relation to thermal time under both moisture conditions was at a linear rate of about 53-56°Cd ± 9.5°Cd tiller⁻¹.
Effect of microclimatic variations, canopy temperature, radiation and photoperiod on the phenology-thermal time relationships have been discussed under both the moisture conditions.     

深山含笑育苗技术及苗木物候与生长规律研究

对深山含笑的种子采集、处理、种子千粒重、优良度及育苗方法进行了观测试验，对其苗木物候、根系生长、苗木生物量分布及苗木高生长规律进行了初步研究。