Screening for resistance to big-vein disease of lettuce (Lactuca sativa)

A methods was developed for screening of breeding populations and evaluation of genotypes of lettuce for resistance to big vein. First and rapid screening of plant populations or large numbers of genotypes was in greenhouse trials by inoculation of the substrate in which the seedlings to be tested were grown with viruliferous zoospores of Olpidium brassicae. Further testing with limited numbers of genotypes was in container tests, using dry soil with viruliferous resting spores as inoculum. No single criterion or simple and early parameter was found to represent fully the final effect of the disease on yield and quality at the time of harvest. Effect on head weight was not correlated with disease incidence or sympton severity. The final effect on promising lines and cultivars could only be studied in field experiments after zoospore inoculation of seedlings in the greenhouse or on naturally infested soil. All 55 lettuce genotypes tested, including American ‘resistant’ crisphead cultivars and breeding lines, developed symptoms of big vein in either test, but there were considerable differences in length of incubation time, sensitivity, and capacity to recover from disease. Loss of head weight was considerable in all nine genotypes tested for yield reduction after early inoculation, and for the crisphead cultivars also after late inoculation. Cos lettuce ‘Lobjoit's Green’ and ‘grasse’ lettuce ‘Little Gem’ are promising parental genotypes for breeding for resistance, as are two entries of Lactuca virosa.     

3种昆虫对蔬菜农药残留的敏感性对比试验

试验采用生物检测法,对3种昆虫在生菜中,对3类农药常规用药浓度下的敏感性做了比较和跟踪试验。试验结果表明,不同的昆虫种类对不同农药品种的敏感性不同,并且,综合评价3种昆虫的试验认为,黄粉虫幼虫更适于蔬菜农药残留的检测和上市蔬菜的安全性监督。     

甘蓝根肿病接种方法的研究

分别比较了菌土接种、蘸根接种对发病的影响,结果显示菌土接种的发病最严重;在接种浓度试验中,浓度越高,发病越重;对不同的根肿菌进行接种比较发现重庆涪陵地区的根肿菌比成都地区根肿菌致病性强,以涪陵地区的根肿菌作为菌源,验证了2个抗病材料99033,99037和2个感病材料99076,99046。并根据实践建立了一套新的田间单株病情分级标准。     

土壤中芸薹根肿菌qPCR检测与风险预警体系的建立与应用

 建立了土壤中芸薹根肿菌荧光定量PCR(qPCR)快速检测及风险预警体系。确定了芸薹根肿菌qPCR检测的特异性引物PbF/PbR,对根肿菌质粒DNA的检测灵敏度为1.612×10^-6 ng·μL^-1,比普通PCR高出1 000倍;对土壤和基质中芸薹根肿菌孢子的最低检测下限均为10 个·g^-1,而土壤和基质带菌的发病阈值分别为100和1 000 个·g^-1,高于该浓度时根肿病发生风险大。本研究建立的芸薹根肿菌qPCR技术体系检测下限远低于发病阈值,可以快速、准确、定量地检测出采自四川绵阳、湖北恩施、江苏无锡、山东青岛、辽宁沈阳、山西运城、内蒙古巴彦淖尔和宁夏固原等8个地区的27份田间土壤中芸薹根肿菌的数量,实现对十字花科根肿病的监测预警,为制定产前病害防控方案提供依据。     

3种昆虫对蔬菜农药残留的敏感性对比试验*

 试验采用生物检测法,对3种昆虫在生菜中,对3类农药常规用药浓度下的敏感性做了比较和跟踪试验。试验结果表明,不同的昆虫种类对不同农药品种的敏感性不同,并且,综合评价3种昆虫的试验认为,黄粉虫幼虫更适于蔬菜农药残留的检测和上市蔬菜的安全性监督。     

Influence of cultivar resistance and inoculum density on root hair infection of canola (Brassica napus) by Plasmodiophora brassicae

The impact of cultivar resistance and inoculum density on the incidence of primary infection of canola root hairs by Plasmodiophora brassicae, the causal agent of clubroot, was assessed by microscopy. The incidence of root hair infection in both a resistant and a susceptible cultivar increased with increasing inoculum density, but was two‐ to threefold higher in the susceptible cultivar; the relationship between root hair infection and inoculum density was also substantially stronger and more consistent in the susceptible cultivar. In the susceptible cultivar, the root hair infection rate peaked between 6 and 8 days after sowing and then declined. In the resistant cultivar, it increased over the 14‐day duration of each study. It appears that examination of root hair infection by microscopy in a bait crop of susceptible canola could serve as a useful tool for estimating P. brassicae inoculum levels in soil. In a separate trial, the relationship between inoculum density and clubroot severity, plant growth parameters, and seed yield was assessed under greenhouse conditions. Inoculum density in the susceptible genotype was strongly and positively correlated with clubroot severity and negatively correlated with plant height and seed yield. In addition, a single cropping cycle of the susceptible cultivar contributed significantly higher levels of resting spores to the soil in a greenhouse test than did a cycle of the resistant cultivar, as assessed by quantitative PCR and microscope analysis.     

甘蓝夜蛾核型多角体病毒(MbNPV)侵染宿主细胞的电镜观察

本文介绍了用电子显微镜观察甘蓝夜蛾核型多角体病毒(Mamestra brassicae L.NPV)感染宿主幼虫的组织病变和病毒复制过程.发现脂肪、体壁、气管组织对MbNPV最敏感.核仁膨大,染色质单个或多个在其中产生并在核膜附近获得囊膜,装配成病毒粒子和病毒束.具有囊膜的核衣壳随机地嵌入多角体蛋白中,形成完整的多角体.细胞核膨大,核膜内陷,核解体,整个细胞充满多角体.而中肠、神经节、马氏管和肌肉组织对MbNPV敏感性差,于感病后期形成小而不规则的多角体.     

甘藍夜蛾成虫期生物学特性的研究

甘藍夜蛾成虫需要取食糖类物质作为补充营养后,才能进行正常的生殖活动。成虫寿命一般8～10天,产卵期約4～7天。雌雄蛾均在夜晚一定时间内进行飞翔、取食、交配、产卵等活动。本试验观察到雌蛾产卵量一般为800～1500粒,最高达2822粒。卵的孵化率超过90%。雌雄蛾均有多次交配现象。雌蛾经人为地与雄蛾完全隔离后,能产下不受精的卵,产卵量低,卵粒不孵化。成虫取食糖类物质,比以清水或非糖类物质作为补充营养产卵高3～5倍。田间观察到成虫在多种蜜源植物上取食。     

晋中地区甘蓝蚜对杀虫剂的敏感性变化及药剂混配的增效作用

为了了解甘蓝蚜对药剂的敏感性变化及药剂混配的增效作用,采用FAO推荐的微量点滴法,测定了山西省晋中地区田间甘蓝蚜种群对药剂的敏感性、相对敏感基线,及不同类型杀虫剂混配的增效作用。结果表明:甘蓝蚜对杀虫剂的敏感性降低,对啶虫脒、高效氯氰菊酯和齐螨素抗药性为原来的11.10倍、14.34倍和16.13倍,对氰戊菊酯、辛硫磷和吡虫啉的抗药性为原来的83.33倍、101.50倍和143.38倍,对灭多威的抗药性为原来的161.75倍;混配增效试验结果表明,辛硫磷和灭多威以有效成分1∶0.5,高效氯氰菊酯和齐螨素以1∶3、1∶6和1∶9混配后都具有明显的增效作用。     

蚜虫枝孢菌对3种蚜虫的毒力测定

在室内测定了蚜虫枝孢菌(Cladosporiumaphidis)对甘蓝蚜(Brevicorynebrassicae)、桃蚜(Myzuspersicae)和茄无网蚜(Acyrthosiphonsolani)的毒力,结果表明,该菌对上述3种蚜虫均有较强的毒力, 1. 0×108 个孢子/mL浓度下在接种后第8d的累积死亡率均达到了80%以上。接种后的前3d为蚜虫枝孢菌的潜伏期,第4~7d是对蚜虫的致死高峰期。蚜虫枝孢菌对3种蚜虫的致死剂量是时间的函数,接种后随着时间的延续,剂量效应逐渐增强,LD50和LD90渐次减小;随接种浓度的增加,时间效应也相应增强,孢子浓度1. 0×105~8个孢子/mL范围内,甘蓝蚜、桃蚜和茄无网蚜的LT50估计值范围分别为7. 5~4. 7, 7. 7~5. 1和7. 4~4. 9。温度的高低影响蚜虫枝孢菌的毒力,在20 ~26℃范围内随温度的升高毒力增强, 26℃以后则毒力随温度升高而下降。24~26℃是蚜虫枝孢菌侵染的最佳温度。