早熟、优质、耐贮梨新品种新梨7号选育研究

以库尔勒香梨为母本,早酥梨为父本,有性杂交选育成新梨７号品种。该品种同时兼备优质、早熟与耐贮藏性;该品种遗传了父本的早熟性,比父本更早熟１５~２０ｄ,盛花期~果实可食期约８０~９５ｄ,属于早熟品种;且遗传了母本品质性状的质地酥脆、耐贮、清香、阳面红晕,比母本果个大,果心小。果柄木质化,丰产抗风。新梨７号果实贮藏期的可溶性固形物、果实重量、果实硬度和果实前期腐烂率的变化与库尔勒香梨基本相似,但耐热能力高于母本。凡适宜香梨、早酥、苹果梨和巴梨种植的地区,都适宜该品种的种植。     

Effects of soil moisture on gross N transformations and N2O emission in acid subtropical forest soils

Soil moisture changes, arising from seasonal variation or from global climate changes, could influence soil nitrogen (N) transformation rates and N availability in unfertilized subtropical forests. A ¹⁵?N dilution study was carried out to investigate the effects of soil moisture change (30–90 % water-holding capacity (WHC)) on potential gross N transformation rates and N₂O and NO emissions in two contrasting (broad-leaved vs. coniferous) subtropical forest soils. Gross N mineralization rates were more sensitive to soil moisture change than gross NH₄ ⁺ immobilization rates for both forest soils. Gross nitrification rates gradually increased with increasing soil moisture in both forest soils. Thus, enhanced N availability at higher soil moisture values was attributed to increasing gross N mineralization and nitrification rates over the immobilization rate. The natural N enrichment in humid subtropical forest soils may partially be due to fast N mineralization and nitrification under relatively higher soil moisture. In broad-leaved forest soil, the high N₂O and NO emissions occurred at 30 % WHC, while the reverse was true in coniferous forest soil. Therefore, we propose that there are different mechanisms regulating N₂O and NO emissions between broad-leaved and coniferous forest soils. In coniferous forest soil, nitrification may be the primary process responsible for N₂O and NO emissions, while in broad-leaved forest soil, N₂O and NO emissions may originate from the denitrification process.     

高速公路建设项目水土保持措施研究

在总结高速公路建设项目组成的基础上,分析高速公路建设引发水土流失特点及危害,提出高速公路建设中水土保持生态恢复的内容、措施体系及其原则,总结2项近年来国内水土保持生态恢复的先进技术.     

精胺对离体小麦叶片过氧化物酶活性的影响

离体小麦叶片在暗处叶绿素迅速分解，过氧化物酶活性升高，精胺处理可以延缓叶绿素降解并且降低过氧化物酶的活性。过氧化物酶同工酶的聚丙烯酸胺凝胶电泳结果显示，衰老叶片除保持原有的３条同工酶活性外，还出现１条新的同工酶，该酶活性随时间延长而上升。精胺处理则一直无此酶的出现。另外，随精胺处理时间的延长，有两条同工酶活性不断降低，另一条基本保持不变。根据过氧化物酶在植物体中的作用，推测精胺保绿作用的机理与精胺抑制过氧化物酶活性或降低过氧化物酶活性有关。     

Detection and characterization of avian leukosis virus in Marek's disease vaccines

Avian leukosis virus (ALV) infection in chickens is known to induce increased mortality, tumors, delayed growth, and suboptimal egg production. Countries importing specified pathogen-free eggs, vaccines, and poultry breeding stock require freedom of infection or contamination with ALV in such products among other avian pathogens. Recently, ALV was found as a contaminant in a limited number of commercial poultry vaccines, even after routine quality assurance procedures cleared the vaccines for commercialization. The contaminated vaccines were promptly withdrawn from the market, and no direct detrimental effects were reported in poultry vaccinated with such vaccines. We describe herein the characterization in vitro of the contaminant viruses. All exogenous viruses detected in four vaccine lots belong to subgroup A of ALV based on cell receptor interaction, subgroup-specific polymerase chain reaction (PCR), envelope gene sequencing, and virus neutralization. A combination of thermal treatment and serial dilutions of the contaminated vaccines facilitated detection of contaminating ALVs in cell culture coupled with antigen-capture enzyme-linked immunosorbent assay. Subgroup-specific PCR readily detected ALV-A directly in the contaminated vaccines but not in naive vaccines or cell controls. Our methods are proposed as complementary procedures to the currently required complement fixation for avian leukosis test for detection of ALV in commercial poultry vaccines.     

棉花产量育种的数量性状分析

产量是棉花育种的主要目标之一，为提高棉花产量育种效率，本文从产量结构模式、产量与其构成因素的相关关系两方面，分析了与棉花产量育种有关的数量性状，并讨论了提高棉花产量遗传潜力的可能性     

鸭源致病性大肠杆菌的血清型鉴定及其相关毒力基因分析

自规模化养鸭场患典型大肠杆菌败血症雏鸭分离的282株致病性大肠杆菌（E.coli）中鉴定出210株（包含37种血清型）,其中O93、O78、O92、O76占43.8%（92/210）为优势血清型,O46、O32＆O93混合型、O60＆O93混合型为首次从鸭群中分离到。应用PCR结合核酸序列测定对210株致病性E.coli（鸭大肠杆菌病分离株）和28株自健康雏鸭泄殖腔拭子分离的E.coli（临床健康鸭大肠杆菌分离株）进行包括强毒力岛（HPI）中的鼠疫菌素受体基因（fyuA）和铁调节蛋白基因（irp2）、Ⅰ型菌毛必需蛋白基因（fimC）、P型菌毛结构基因（papA）和血清耐受基因（iss）检测,结果表明：fyuAi、rp2、fimC、papA和iss基因在鸭大肠杆菌病分离株的携带率分别为41.0%、43.3%、92.9%、97.6%和96.7%,在临床健康鸭大肠杆菌分离株的携带率分别为21.4%、25.0%、92.9%、100%和92.9%,患病鸭和临床健康鸭大肠杆菌分离株iss、fimC和papA携带率差异不显著（P〉0.05）,但papA的携带率均显著高于其他宿主（鸡、猪和人）源E.coli;HPI毒力岛在鸭源E.coli中分布较广,其携带率表现为鸭大肠杆菌病分离株极显著高于临床健康鸭大肠杆菌分离株。HPI毒力岛的携带率与菌株的致病性呈明显的正相关,与O78等特定的血清型有一定的关系。鸭大肠杆菌病分离株有37.6%（79/210）同时携带fyuAi、rp2、fimCi、ss和papA基因,极显著高于健康鸭大肠杆菌分离株的14.3%（4/28）（P〈0.01）。     

烟草气候斑病的发生规律及防治

１９９０－１９９４年研究结果表明，低温是诱发气候斑病的主要因素，不同品种抗性差异显著，氮钾比失调，偏施碳铵地发病严重，当大面积种植感病品种，寄主处于感病阶段，遇气温突然下降和多雨时，最易流行。在防治上，采取以农业防治为主、化学辅的有效措施。     

不同结构甘蔗群体生理动态变化及产量差异

为进一步探讨甘蔗栽培的高糖高产理论，试验以新台糖22号为材料，研究甘蔗种植行距为1.0m（处理A）、窄行宽株，行距为1.25m（处理B）、宽行窄株，行距1.5m（处理D）、宽窄行宽株，行距2.0m（处理C）、宽窄行窄株四种种植结构及其群体生理生化动态变化及甘蔗产量之间的差异。试验结果表明：叶绿素含量、净光合速率、蒸腾速率等生理生化指标，在各处理的表现均是分蘖期较高，伸长期最高，工艺成熟期低，但各处理之间差异不显著；每666.7m2蔗茎产量最高是处理D，为9170kg/666.7m2，最低是处理C，为7427kg/666.7m2，处理D与处理C之间差异达5%显著水平；蔗糖分最高是处理B，为15.5%，最低是处理D，为15.2%。     

玉米抗旱性遗传特性及其简化模型的研究

[目的]干旱是限制我国玉米生产的主要因素,研究干旱胁迫下玉米抗旱性的遗传特性,为合理利用优良自交系配置杂交组合提供理论依据.[方法]采用完全双列杂交Griffing方法I,研究不同玉米双亲杂交组合对其F1代抗旱性的贡献.[结果]F1代抗旱性超双亲、低双亲、介于双亲之间的比例分别为12.2;、20;、67.8;;F1代及其双亲的抗旱性关系符合加性模型R子=0.593R母+0.431R父;F1代及其双亲之间的抗旱系数在一定程度上可用极为简单的代数关系描述:XY+ YX =XX+ YY.[结论]玉米杂交后代的抗旱性取决于母、父本双亲的抗旱性,母本的抗旱性贡献略大于父本;正反交F1代抗旱性之和基本等于双亲抗旱性之和.