稻曲病菌越冬厚垣孢子萌发力及其侵染力的研究

THE CAPACITY OF GERMINATION AND INFECTION OF OVERWINTERED CHLAMYDOSPORES OF USTILAGINOIDEA VIRENS (COOKE) TAK.

通过3年系统测定试验,稻曲病菌越冬厚垣孢子在室内和水泥池的土中可以存活5—6月。在种植油菜、苕子、蚕豆、小麦的露天水泥池中,越冬的厚垣孢子均有萌发力。在油菜、苕子、小麦3种越冬作物大田土中越冬的厚垣孢子的萌发率以油菜田最高,为2.04‰。越冬后种子上的厚垣孢子数量大,萌发率可达0.4％—2.97％。稻茬中越冬的厚垣孢子和在3cm浅土中的厚垣孢子,其萌发率分别较冬闲田或冬作田土中和15cm深土中高。越冬厚垣孢子可以侵染早稻的种子、芽鞘、苗叶和苗根,并引起穗期发病。用水泥池内和种子上越冬的厚垣孢子液注射稻穗和涂抹穗苞均可致病。在上年发病的水泥池栽种水稻亦能引起发病。

According to the results of a three years study, the overwintered chlamydospores of Ustilaginoidea virens (Cooke) Tak. could survive untill May or June in the laboratory and pondlets. Overwintered chlamydospores maintained the capacity of germination in soil of pondlets or the field in which different winter crops were planted. The amount of overwintered chlamydospores in the surface of rice seeds was great and maintained capacity of germination. The germinating rate of overwintered chlamydospores in rice stubble and 3cm deep soil was high. By artifical inoculation overwintered chlamydospores could infect seeds, buds, seedling leaves and seedling roots of early rice. By injection and smear method the spikes and the leaf sheaths of emerging spikes of middle rice plants with chlamydospores which overwintered in seeds and pondlets could cause infection.