保亭县晚稻“3414”肥效试验

通过海南保亭晚稻“3414”肥效试验,建立了此试验条件下的三元二次和一元二次回归方程模型。结果表明：三元二次方程差异达到极显著水平,预测最佳施肥量的方案为：施N 6.22kg/667m2,P2O51.14kg/667m2, K2O 4.73kg/667m2,氮磷钾比例为1∶0.18∶0.76;缺素区氮素相对产量为83.83%,磷素为92.19%,钾素为87.3%,各单质肥料对水稻产量贡献率依次为氮＞钾＞磷,该试验地土壤养分,氮、磷、钾均为中等肥力。     

急性温度胁迫对大口黑鲈存活率及肝脏生化指标的影响

为了探究急性高温胁迫对大口黑鲈(Micropterus salmoides)“优鲈3号”存活率及肝脏生化指标的影响,将25℃(对照组)下暂养的大口黑鲈“优鲈3号”直接放入31、34、37℃水环境中,测定不同温度应激后鱼体的存活率及肝脏生化指标。结果表明:37℃组成活率低于31℃、34℃组,仅为50%。31℃和34℃组T-SOD、GSH-PX、CAT、LZM、AKP和ACP活力在48 h显著高于对照组。37℃组则与对照组无显著差异,且ACP活力在48 h显著低于对照组。结果表明,在培育大口黑鲈“优鲈3号”鱼苗时温度应该保持在34℃以下。     

牙鲆"鲆优2号"不同养殖地点生长和存活性状的基因型与环境互作分析

为比较牙鲆"鲆优2号"在不同养殖地区的生长和存活性能,实验利用连续多代对生长性状和抗迟缓爱德华氏菌病性状遗传参数评估和基因组选择的结果筛选出的亲本,建立28个"鲆优2号"家系,在河北(Site 1)和山东(Site 2)进行对比养殖试验,利用混合线性动物模型对生长和存活性状进行了基因型与环境互作分析。Site 1和Site 2的平均日增重分别为1.5和1.2 g/d,养殖成活率分别为81.4%和82.2%,"鲆优2号"在两个养殖地点的生长和抗病性能均表现优异。不同养殖环境间收获体质量和存活性状的遗传相关分别为0.57(<0.7)和0.82(>0.7),说明不同养殖环境间收获体质量存在显著的基因型与环境互作效应,但是不同养殖环境间存活性状的基因型与环境互作效应不显著。研究表明,牙鲆"鲆优2号"新品种在不同养殖地点的生长和存活性能均表现良好,为保证良好的推广效果,需要对牙鲆的制种方案进一步优化,针对不同的养殖地区进行"鲆优2号"苗种生产,或培育具有普适性的"鲆优2号"苗种,保证在不同养殖环境下的快速生长和高存活率优势。     

Concentrations of total nitrogen in squash,cucumber and melon in relation to growth,and to a piper‐steenbjerg effect

Abstract

Squash (Cucurbita pepo), cucumber (Cucranis sativus), and sweet melon (Cucumis dudain) were grown in sand cultures with N supply concentrations as the variable. For several reasons, total‐N values were found to be less satisfactory than NO ‐N for the purpose of determining the critical nitrogen concentration for maximum growth. Concentrations of total‐N in mature petioles were higher in plants severely deficient in N than in less deficient plants, characteristic of a Piper‐Steenbjerg effect.     

农机安全生产“三大”防线探讨

农机的安全生产与农业机械化进程密切相关,关系到人民群众的生命财产安全。构筑农机安全生产"三大"防线是农机安全生产的重要保障。文章对如何落实农机安全生产"三大"防线进行浅要分析。     

离体砂糖橘黄龙病病果中病菌浓度变化规律的探究

Early studies have revealed the uneven distribution of Candidatus Liberibacter asiaticus (CLas) in Huanglongbing (HLB)-affected citrus trees. Bacteria of CLas were found to be enriched in the fruit, especially in the pith. In this study, we further investigated the dynamics of CLas population in excised citrus fruits. The CLas-infected Shatangju fruits were collected and kept for 4 weeks under constant temperature and moisture. The concentrations of CLas in the pith of fruits were detected weekly, and the fruits on trees were detected at the same time as the control. Our results showed that the total DNA, citrus DNA and CLas DNA from the excised fruits all decreased during the storage, but the CLas concentration in the pith of excised fruit increased firstly, and then decreased with time. The CLas concentrations in the pith of diseased fruit at 14 d and 28 d after picking were higher than that of the first day and reached the highest at 14 d. Comparing with the fruits on the tree, CLas concentrations in the pith of excised fruits were also significantly higher at the 14 d and 28 d. With the degrading of total DNA in fruit pith, the proportion of CLas DNA was increased, which could be served as a suitable material for the DNA extraction and CLas genome sequencing.     

TTI交联聚乙烯醇木材胶黏剂的研究

研究在水基中三苯基甲烷-4,4',4"-三异氰酸酯(TTI)交联聚乙烯醇(PVA)所形成的白色乳胶。采用正交试验法探讨聚乙烯醇、催化剂-x、TTI的加入量、反应时间及反应温度对该乳胶性能的影响。合成的单组份环保乳胶适用于木材、纸品等加工业,以及建筑业。     

海岛棉不同果枝品种间杂交产量性状的遗传及F1和F2群体优势分析

采用MINQUE（1）统计方法及AD模型对9个海岛棉品种（系）及其20个F1组合9个产量性状的两年资料进行了遗传分析。结果表明，海岛棉长果枝与零式果枝品种间杂交，各产量性状均存在极显著的加性效应方差比例；衣分、铃重、霜后铃数、总铃数和皮棉产量存在极显著的显性效应；均存在显性与环境的互作。品种3836具有霜前铃数和霜前     

试用“SWOT”法探讨我国茶叶国际市场竞争力及其对策

茶叶出口在我国茶叶经济中起龙头带动作用,茶叶无论在国内还是在国际市场都有着长远发展的产业价值。本课题在运用经济比较学原理同时,采用西方流行的分析模式 — — “SWOT”法,分析评价在 WTO条件下我国茶叶出口的优势、薄弱点、面临的机遇和威胁,明确我国茶叶在国际市场竞争中的地位和实力、提出我国宜发展具有竞争优势的绿茶及特种茶、实施绿色营销、内外销茶标准并轨且与国际标准接轨、统一出口茶叶标识。