稻区杂草上的梨孢菌与稻瘟病发生的关系

EFFICTS OF WEED-HOSTS OF PYRICULARIA ON INCIDENCE OF RICE BLAST DISEASE

从水稻和稻田周围常见的１０种杂草上来集梨孢属菌株，以涂沫法作交互接种，分离自牛筋草、狗尾草、法氏狗尾草、李氏禾、罗氏草、铺地黍、稗和马唐的梨孢菌与分离自水稻的梨孢菌可以交叉侵染其寄主，茭白和碎米莎草梨孢菌与稻梨孢菌不能交互侵染；自然诱发条件下来自牛筋草和狗尾草的梨孢菌与来自水稻的梨孢菌对其寄主同样发生交叉侵染。直接从杂草寄主上分离的梨孢菌株对水稻的致病性较弱，接种到水稻感病品种发病后再分离的菌株，对水稻致病性增强，对原寄主的致病性基本保持不变。推断稻瘟病区稻田周围牛筋草、狗尾草、法氏狗尾草、李氏禾、罗氏草、铺地黍、稗和马唐等杂草寄主上的梨孢菌在稻瘟病菌的积累和传播方面具有作用。

Pyricularia isolates were collected from 11 plant species , including rice and common weeds in paddy fields , and inoculated respectively to all these plants by smearing leaves with the spore suspen- sions. The Pyricularia isolates from Eleusine indica,Setaria viridis,S faber, Leesia hexandra, Digi- taria sanguinalis, Rottbellia exaltata, Panicum repens, Echinchla crusgalli were able to infect rice plant. , and the rice isolate.were able to infect these weed plant. , too. The fungal isolated from Ziza- nia latiforia and Cyperus, iria were not able to infect rice plants and the rise isolates were not able to in- feet these two plants. In the natural disease nursery , the isolates from E.indica or S. viridis were able to infect rice planis and the rice isolates were able to infect both plants. All of the isolates from weeds showed mildly pathogenic to rice, but their virulence could be improved by inoculating blast- suscepitble rice cv.and re-isolated from the lesions. The re-isolates however, showed the original lev- els of the virulence on cheir former host plants. The weed hosts of the blast pathogen might be epi- demiologicaly important and a direct bearing on the disease cycle of rice blast. -