湘东地区三熟制油菜播期及适宜密度研究

为探讨湘东地区三熟制直播油菜不同播期下的适宜栽培密度,2010 ～2011年度,以偏早熟油菜品种丰油730为材料在醴陵市进行了播期与密度田间试验.结果表明:湘东地区三熟制栽培,10月10 ～30日播种,播种越早产量越高,适宜播期为10月25日前.10月10日播种,密度以37.5万～45.0万株/hm2较为适宜;10月15 ～20日播种,适宜的密度范围为45.0万～52.5万株/hm2;10月25日播种,52.5万～60万株/hm2的密度较合适;10月30日播种,密度应达到60万株/hm2.     

密集烘烤关键温度点稳温时间对烤烟理化性状的影响

针对密集烘烤存在的干物质降解不充分和香气物质不足的问题,以K326品种为材料,在湖南省浏阳市开展了密集烘烤关键温度点稳温时间对烤后烟叶物理特性和化学成分影响研究.结果表明,在烟叶变黄期和定色期适当增加稳温时间,可增大烟叶收缩形变,降低叶质重,降低单叶重,增加烟叶疏松性,降低烟叶淀粉含量,增加总糖和还原糖含量.但过度延长稳温时间,将导致烟叶内含物消耗过多,降低烟叶品质.对中部和上部烟叶,在变黄期的38℃稳温24h和42℃稳温16 h,在定色期的47℃稳温18h和54℃稳温16 h为适宜;对下部烟叶,在变黄期的38℃稳温15 h和42℃稳温16 h,在定色期的45℃稳温12 h和54℃稳温16 h为适宜.     

收获期对春植花生种子繁殖的影响

研究结果表明,春植花生种子中蛋白质、脂肪和亚油酸含量与产量一样均随着荚果发育而呈增加趋势;油酸含量却呈下降趋势。播后90d以前收获的种子,出苗率低,植株长势弱,产量低,繁殖系数小。播后95d种子的出苗率及繁殖系数等与充分成熟的种子差异不明显,为最早适收期。     

北方冬季室内饲养灰飞虱的方法

以水稻苗和小麦苗作为灰飞虱寄主植物,探讨了北方冬季室内饲养灰飞虱的方法。结果表明,该技术简便易行,能够准确把握虫龄,可大量扩繁也可单头饲养,具有成本低,易操作,灵活性好等特点;试验测定了在28℃条件下,若虫存活率可达到95.36%,单雌产卵量达到177头。     

固定式饲草压捆机再次改进研究

在中试过程中,主要根据自行研制的固定式饲草压捆机,针对触发弹射式杠杆组分捆机构及其相关机构进一步改进。将分捆机构移至距离压缩止点260mm处,使允许落板时间增至0.795s,而分隔板自由下落时间为0.271s,因此撤去弹射器,简化了结构,还避免了弹跳反射。由于不同种类、不同含水率的饲草压缩反弹量区别较大,将曲柄长度改为480mm,延长了压缩行程,避免饲草反弹堵塞落板口。     

粉煤灰不同掺量对混凝土碳化的影响

对于不同养护龄期、不同粉煤灰掺量及不同水胶比对混凝土碳化的影响进行研究,混凝土的碳化深度与碳化龄期之间的关系可用幂函数D=αTβ进行曲线回归分析,且相关性较好。结果表明,随着粉煤灰掺量及水胶比的增大,混凝土的碳化越严重;混凝土养护龄期越长,混凝土的抗碳化性越好。养护不充分时,高掺量粉煤灰混凝土后期碳化增长速率快;养护较充分时,粉煤灰掺量越小,混凝土早期抗碳化性越好,粉煤灰掺量越大,混凝土后期碳化增长速率越慢。当养护较充分时,水胶比为0.35,粉煤灰掺量为45%时,粉煤灰混凝土抗碳化性较好,能满足工程要求。     

Sowing time and prediction of flowering of different hemp (Cannabis sativa L.) genotypes in southern Europe

Fibre hemp can be grown under a wide range of agro-ecological conditions, but it requires special attention for several physiological features and crop management. A management strategy in order to reduce inputs and thus achieve acceptable yield could be achieved optimizing sowing time. With this respect, the effects of sowing date on hemp biology and yield was studied, using two monoecious and two dioecious genotypes. Field experiments were carried out in two subsequent years (2003-2004) in South of Italy, using drip irrigation system. Sowing time, in the two year period, ranged between March 10th and July 22nd. Optimal sowing time was observed between the end of April and the first three weeks of May; in that range, the dioecious Fibranova yielded the most in terms of aboveground biomass and stem dry yield, followed by Tiborszallasi, while the two monoecious showed the lowest yield. On the contrary, before and after that period, the shorter day length caused an early floral induction that strongly reduced stem and fibre elongation, and thus aboveground dry biomass and consequently stem yields. Based on this study a simulation model focusing on flowering prediction in Mediterranean environment was developed.     

Cost minimization and input substitution in the production of gilthead seabream

Abstract

This paper studies cost minimization decisions by utilizing a simple bioeconomic model for gilthead seabream (Sparus aurata). This model is based on a biological growth model which accounts for the effects of temperature and ration size. Although the implicit production function derived from the growth model is shown to be quasiconcave, it is not homothetic nor quasilinear. Further, technology shows increasing returns with respect to ration size and harvesting time. Optimization decisions are analyzed in two different contexts, a restricted biological setting and an expanded economic problem. It is shown that the optimal ration size increases for the latter context, reaching values commonly accepted in current industrial practice. Even though the elasticity of substitution to the shadow input prices is positive at the optimal ration size, the latter is rather robust to changes in input prices. However, optimal costs show larger sensitivity to the labor price than to the feeding and managerial costs.     

九连山常绿阔叶林冻雨灾害后林分的受损与恢复

对2008年初南方冰雪灾害在江西九连山常绿阔叶林造成的损失状况做了研究.对受灾林地19 128株林木(D≥1 cm)的受灾情况进行了对比分析.对不同径级和不同树高因子下林木的受损状况差异做对比.统计检验结果显示:林木爱损状况存在着显著的径级差异和树高差异.低矮的树木(H＜6 m)趋向于被压弯,而翻蔸和腰折易发生在高的树...     

乌拉坦对鲫的麻醉效果

在鲫Carassius。啪￡峪适宜生存温度（室温为15—25℃）条件下,研究了10、20、30、40、50g／L的乌拉坦（Urethane）溶液（pH为7．0＋0．44）对鲫（体质量为230g±9．46g）的麻醉效果,探讨了乌拉坦对水生动物的麻醉作用,并提供日常实用的麻醉参数。结果表明：乌拉坦浓度为10～50g/L时,麻醉时间随着乌拉坦浓度的增大而缩短,复苏时间随着乌拉坦浓度的增大而延长,但浓度为50g／L时与浓度为40g／L时相比,鲫的复苏时间无显著性差异（P〉O．05）;浓度为10-40∥L时,各组鲫的复苏率均为100％,浓度为50g/L时,鲫的复苏率为88％;浓度为10-50g/L时,各组鲫7d的存活率均为100％。鲫在不同浓度（10～50g／L）的乌拉坦溶液中药浴一定时间后,将其暴露于空气中,经过一定时间后鲫可自动苏醒而弹起。其中除50g／L浓度组与40g／L浓度组之间,鲫的弹起时间无显著差异（P〉0．05）外,其余浓度组之间鲫的弹起时间均有显著差异（P〈0．05）;各浓度组药浴时间为10min与5min之间,鲫的弹起时间无显著差异（P〉0．05）,10g／L组的药浴时间为25min与20min之间,鲫的弹起时间无显著差异（P〉0．05）,各浓度组其余药浴时间之间均有显著差异（P〈0．05）。各试验组鲫7日存活率均为100％。药浴后的鲫能够恢复正常行为状态,表明乌拉坦对鲫行为的影响无明显的后遗效应。综合各项试验结果,表明乌拉坦对鲫的麻醉安全浓度为40g／L。