南方根结线虫1号小种对烟草抗病品种致病性变异研究

分别循环接种南方根结线虫1号小种虫卵于抗病烟草品种中烟14和感病烟草品种红花大金元幼苗,以探索该线虫对抗性烟草品种的致病性变异情况.结果显示,随着南方根结线虫1号小种繁殖世代的增加,其对中烟14的致病能力逐渐增强,连续繁殖5代后致病力差异显著,而该线虫对红花大金元的致病力变化不明显,表明南方根结线虫1号小种与其抗病品种连续互作可以导致其致病性增强.     

曲霉发酵液对烟草根结线虫的作用

室内测定了一株曲霉发酵液对烟草根结线虫优势种群南方根结线虫（Meloidogyne incognita）2龄幼虫、卵囊和散卵粒孵化的影响。不同稀释浓度发酵液的处理和无菌水处理有显著差异,发酵液的1倍液以上浓度与10μtg／ml涕灭威的防效相当,对2龄幼虫的致死率在90％以上,对卵囊和散卵粒孵化的抑制率在95％以上。     

Suppression of plant parasitic nematodes in the chinampa agricultural soils

Soil from the chinampa agricultural system in the Valley of Mexico suppressed damage by plant-parasitic nematodes to tomatoes and beans in greenhouse and growth chamber trials. Sterilization of the chinampa soil resulted in a loss of the suppressive effect, thereby indicating that one or more biotic factors were responsible for the low incidence of nematode damage. Nine organisms were isolated from chinampa soil, which showed antinematodal properties in culture. Naturally occurring populations of plant-parasitic nematodes were of lower incidence in chinampa soil than in Chapingo soil.     

α-Tomatine and resistance of tomato cultivars toward the nematode,Meloidogyne incognita

Susceptible and resistant tomato cultivars were assayed for root tomatine concentrations at different developmental times. No correlation between high tomatine levels and resistance towardMeloidogyne incognita was apparent. In plants infected with nematodes, tomatine in the roots was the same as in uninfected controls. Tomatine concentration, as measured by bulk analysis, does not appear to play an important role in resistance toward the nematode studied.     

球孢白僵菌Snf907发酵液对番茄根结线虫病的控病效果及防御酶活性影响

研究球孢白僵菌Snf907不同浓度发酵液对番茄幼苗期南方根结线虫病(Meloidogyne incognita)的室内防效,并测得处理后番茄幼苗根内几种主要寄主防御反应酶系PAL、POD、PPO、SOD和可溶性蛋白PRO活性的动态变化.结果表明:不同浓度的发酵液对根结和卵囊的抑制率均明显高于对照,其中原液和5倍稀释液达到80%以上.不同浓度发酵液处理后番茄幼苗根部的PAL、POD、PPO、SOD活性均高于对照,PRO活性显著增加.显示了球孢白僵菌在促进植物生长方面的潜能.     

茼蒿甲醇提取物不同萃取组分对南方根结线虫发育的影响

采用液-液分配法对茼蒿甲醇提取物进行了萃取分离,得到石油醚、三氯甲烷、乙酸乙酯、正丁醇、水等5种不同萃取组分;采用室内培养和盆栽试验的方法,研究了5种萃取组分对南方根结线虫发育的影响。结果表明:茼蒿甲醇提取物水萃取组分对南方根结线虫胚胎发育和胚后发育的抑制作用最强。1%茼蒿甲醇提取物水萃取组分处理后264h,仅有15%的卵完成胚胎发育;胚后发育历程、初侵染、初产卵日分别推迟4、5、9d,雌虫产卵量显著降低。     

腐植酸类物质对温室黄瓜根际植物线虫数量的影响

本研究旨在明确3种腐植酸类物质(NaFA、KFA、CFA)及与新药肥(SY)复配物对温室黄瓜根际植物线虫数量是否有抑制作用.研究结果表明:(1)矮化线虫属Tylenchorhynchus和根结线虫属Meloidogyne是2种主要的植物线虫,(2)随着生长季后期植物线虫数量的迅速增长,5种腐植酸类物质(CFA、NaFA、KFA、OFA SY、NaFA SY)及SY防治区矮化线虫和根结线虫数量低于对照区,(3)CFA与新药肥SY复配效果强于OFA和SY的单一作用效果.     

Responses of plant-parasitic nematodeMeloidogyne incognita to carbon dioxide determined by video camera-computer tracking

A computer tracking system was used to quantify the responses of infective second-stage juveniles of the plant-parasitic nematodeMeloidogyne incognita to carbon dioxide. A sudden increase in concentration caused an increase in the rate of locomotion and a decrease in the frequency of changes of direction. The threshold was about 0.01 % vol CO₂/vol gas when the baseline concentration was very low and 0.05% CO₂ when the baseline concentration was 1% CO₂. The latter value represents a relative change of 5%. Concentrations above 10% CO₂ caused a general decrease in movement. In a second type of experiment, a constant concentration gradient of CO₂ was established, and the net movement of the nematodes along the gradient was determined. At low concentrations, the threshold was about 0.02% CO₂/cm. At higher concentrations, the threshold gradient was below 0.01% CO₂/cm or a relative gradient of less than 1% change/cm. At all concentrations to which nematodes responded they were attracted. The degree of orientation was estimated to be approximately 10% under most conditions. The rate of migration under the most favorable conditions was about 0.7 cm/hr. Three possible functions of the response are discussed: attraction to roots, movement toward optimal depth in soil, and as a collimating stimulus.