【摘要】 为查明杂草根在青枯菌病害循环中的作用;用烟草青枯菌液浸注接种烟苗叶片后产生枯斑的迟早及扩展程度取决于接种体浓度,菌液浓度愈高,烟株枯死就愈快。用42种杂草根处理液接种烟苗后显症速率有很大差异,胜红蓟、牛繁缕等7种根处理液接种后2~3d叶片出现枯斑,10d内烟株枯死;千金子、看麦娘等27种根处理液接种后5~7d叶片出现枯斑,11~20d烟株枯死;座地菊、小蓬草等8种根处理液接种10d后只在叶片上出现黄斑-枯斑;病斑不扩展,镜检可见溢菌。用8种杂草根处理液涂抹在改良的SM-1平板上培养分离,胜红蓟和牛繁缕检出菌量104cfu/g根,千金子、看麦娘等4种检出103cfu/g根~102cfu/g根,座地菊和小蓬草未分离出青枯菌。结果表明杂草根处理液接种烟苗后显症迟早、枯死快慢与在改良的SM-1平板上分离菌量之间呈负相关。此法可用于烟草青枯病的侵染源带菌检测。更多还原

【Abstract】 Initial results showed that after tobacco seedlings were infiltrated into bacteria of Ralstonia solanacearum, the symptom displaying time and the expanding area of bad dead spot in the leaves were decided by the concentration of the bacteria. Higher concentration of bacteria led to more quickly wilting of the plant. Research showed that the speed of symptom display in the leaves greatly varied among the tobacco seedlings infiltrated into different liquid root extracts from 42 kinds of weeds. The symptom of brown spot appeared in the leaves within 2～3 days and then the plants wilted within 10 days after the seedlings were infiltrated into 7 kinds of liquid extracts, such as those from Ageratum conyzoides L. and Malachium aquaticum (L.) Fries., while the symptom appeared within 5～6 days and the plants wilted within 11～20 days after infiltration into 27 kinds of liquid extracts, such as those from Leptochloa chinensis (L.) Nees and Alopecurus aequalis Sobol. The symptom of small yellow or brown spot appeared after 10 days infiltration into 8 kinds of liquid extracts, such as those from Soliva anthemifolia R. Br. and Erigeron Canadensis L.. These spots did not expanded, but the spilled bacteria could be detected in leaves under microscope. Then, 8 kinds of liquid extracts were smeared on the modified SM-1 culture plates to check the concentration of the bacteria of Ralstonia solanacearum. 104 cfu/g roots were detected in liquid extracts from roots of Ageratum conyzoides L and Malachium aquaticm (L.) Fries., 10+3～10+2 cfu/g roots were detected in liquid extracts from 4 kinds of roots, such as Leptochloa chinensis (L.) Nees and Alopecurus aequalis Sobol., while no bacteria were detected in the liquid extracts from roots of Soliva anthemifolia R. Br. and Erigeron Canadensis L.. The results showed that there was a positive relationship between the concentration of bacteria in liquid root extract and the speeds of symptom display and plant wilting. This method can be used to detect the bacterial source of tobacco bacterial wilt diseases.更多还原