一种新的棉花苗期黄萎病病情指标

 在丛枝菌根菌(AMF)诱导棉花抗/耐黄萎病的研究过程中发现植株叶柄带菌(Verticillium dahliae,VD)量和木质部变色指数的指标与棉株的发病率和病情指数无相关关系。无症健株带苗率达10%以上;从茎基部测定的木质部变色指数不能反映其抗/耐黄萎病的差异。作者提出了"棉株茎木质部非变色高度"的概念,并发现只有当不质部非变色高度≤株高的50%时,叶片才显黄萎症状。与此相应所提出的木质部非变色级与病级、木质部非变色指数与病情指数则具有一定相关关系。木质部非变色指数可作为棉花苗期黄萎病的病情指标。     

Health status of the pear tree following the establishment of Fire blight in Northern Tunisia

ABSTRACT

Pears have great importance in Tunisia for their desirable taste and commercial value. Until 2012, the pear cultivation was protected against fire blight by the application of a rigorous quarantine system. Fire blight, caused by Erwinia amylovora, was outbreak in Tunisia in the spring of 2012 and has spread rapidly through the most important pear growing regions destroying several hundred hectares of pear plantations. Therefore, the total pear production has decreased from 60,000 metric tons in 2011 to less than 20,000 metric tons in 2016. In this study, collected data of pear culture and surveys were carried out during four years (2012–2016) in the main pear growing areas to evaluate the current situation of the disease in the country particularly in the damaged regions of the lower valley of Medjerda (Manouba, Ben Arous, Bizerte, and Beja). Samples collected from symptomatic trees were processed for the isolation and identification of the causal agent using microbiological and molecular techniques. The results indicate that the disease had destroyed more than 5500 hectares among a total of 8400 hectares of pear plantations area. Both provinces Manouba and Ben Arous were the most affected by fire blight disease resulting in the eradication of 350 and 325 hectares of pear plantations, i.e., 100% and 98% of the total infected area, respectively. All control attempts, including sanitary measures, the application of mineral oil and copper, growth regulators and biological control have failed to limit the spread of the disease. The presence of pathogen in the prospected regions was confirmed by pathogenicity and molecular tests, which are compatible with the symptoms observed throughout the surveys. The pear cultivation in Tunisia is threatened by fire blight due to the restriction tolerance of the available varieties and the climatic conditions favoring the staggered flowering of the species. Quarantine measures must be implemented to prevent the spread of this disease in a new disease-free areas.     

大白菜抗感品种间作提高感病品种抗病毒病能力研究

为了探讨通过抗感品种间作栽培方式来提高大白菜品种抗病毒病的能力,采用小区试验和对黑龙江大白菜区试与生试结果分析。结果表明,抗感品种间作可提高感病大白菜品种抗病毒病能力;抗性不同的品种间作使同一品种在区试、生试中表现出不同的抗性,与对照相比表现出不同增产幅度。     

核果类果树褐腐病在重庆的发生与防治初报

近年随着乡村产业调整和果业发展, 褐腐病在我国的发生呈加重趋势。本文对重庆地区核果类果树褐腐病的发生状况做了调查分析, 在室内通过平板及离体果实试验, 筛选拮抗菌和化学药剂, 为田间防治实践提供科学依据。主要结果如下:桃褐腐病在重庆普遍发生, 核果类果树均易感, 病原菌经鉴定为果生链核盘菌Monilinia fructicola; 系统调查初步分析发现, 降雨时间与李褐腐病发生发展关系最密切, 其与病情指数增幅的相关系数R=0.94(P<0.05); 平板对峙和离体桃果筛选, 获得2株有生防潜力的放线菌YLS5-2和YYDB3-1, 二者的抑菌率分别为91.3%和84.5%, 相对防效分别为65.1%和67.1%, 可能具有较好的应用前景; 平板毒力测定和离体桃果控病试验, 效果最优的化学药剂分别为戊唑醇、苯甲·丙环唑, 其中戊唑醇在推荐浓度处理96 h其离体果实防效仍维持在100%水平。     

Interactions of soil microorganisms on growth and disease incidence of pepper (Capsicum annum)

The effect of interactions between soil borne pathogen, Phytophthora infestans the antagonistic organism Trichoderma viride and Arbuscular mycorrhizal Glomus etunicatum on growth and disease severity of pepper Capsicum annum was investigated in a greenhouse experiment. Pepper seedlings inoculated with the pathogen alone had sever disease symptoms. While those inoculated with mycorrhizal alone had the highest flowering and fruiting values, followed by the pepper seedlings inoculated with Trichoderma viride. But pepper seedlings simultaneously or dually inoculated with the three microorganisms also had good growth parameters, such as early and high flowering incidence, fruit maturity increase in leaf number, height and growth, while the effect of the pathogen was highly suppressed.     

杨树溃疡病发生因素的调查研究

通过对辽宁省朝阳县羊山镇1990~1998年间营造的各类品种杨树发生溃疡病情况的调查,结果表明:栽植时一次性浇足水分(150 kg.穴-1)发病率仅为0.48%。说明浇水不足是引发生杨树溃疡病的重要因素;起苗时苗木根系损伤严重的,发病率较高;不同品种类型的苗木杨树溃疡病发生率有明显差异;欧美杂交杨和新疆白杨派抗病能力强,青杨派树种抗杨树溃疡能力差。     

应用灰色关联对不同品种烟叶内在质量的分析

灰色关联分析是灰色理论中的一种分析方法,这种方法的基本思想是根据所研究的因子间变化的相似程度来判断关联程度。应用关联分析的这一原理,通过各种内在质量对综合评分的关联系数(k)及关联度r,研究影响综合评分的主要内在质量的影响程度,分析了烟草内在质量与综合评分之间的关联度,结果表明烟草主要内在质量与综合评分之间的关联度依次为糖碱比>糖差>总糖>还原糖>氮碱比>K2O%>总氮>蛋白质>烟碱,为云南优质烤烟质量标准体系建立提供一种简捷、科学的理论分析方法。     

二氢吡啶在奶牛养殖中的应用研究

将二氢吡啶添加到奶牛日粮中，进行饲养试验。结果表明，试验期末，试验组奶牛产奶量与对照组相比提高5．65％，未达显著水平；奶料比、乳脂率、乳蛋白含量与对照组相比无变化。试验组奶牛乳房炎的发生率与对照组相比降低61．95％。     

Increasing relative maturity alters the base mineral composition and phenolic concentration of avocado fruit

The effect of increasing fruit maturity on fruit base mineral composition, phenolic content and the resultant influence on postharvest fruit quality and ripening physiology of ‘Fuerte’ avocado was investigated. Late harvested fruit with increasing maturity had reduced calcium and magnesium concentrations. A reduction in ripening time was associated with a decrease in fruit calcium concentration. The relationship, if any, between fruit potassium concentration and relative maturity was less clear. Total fruit phenolics increased with increasing fruit maturity and this was associated with an increased incidence of the cold storage browning disorder, mesocarp discoloration. Cold storage had no effect on total fruit phenolic concentration.