十字花科白菜根肿病菌在不同温度、pH值条件下致病性差异研究

Study on Pathogenicity Difference of Plasmodiophora brassicae under Different Temperature and pH Value

采用根肿病菌和土壤混合法,在休眠孢子浓度1×108（个/g土）条件下,设置7个温度及6个土壤pH值梯度,进行根肿病菌对白菜致病性测定,90 d后拔根调查根肿病菌侵染发病情况.测定结果,在pH值6时,不同温度梯度间白菜根肿病发病株率存在较大差异,其发病株率从高到低的温度为30℃＞25℃＞20℃＞35℃＞15℃＞10℃＞5℃.5和10℃条件下,其根肿病菌侵染力弱,不发病或发病株率较低;15 ～ 30℃条件下随温度升高发病率增加,但在35℃条件下,发病株率降低.温度25℃条件下,pH值为4、5、6、7、8、9的白菜发病株率分别为80.36％、100％、65％、10.77％、3.23％、0.0％.pH值4发病率虽高,但白菜生长受抑制,生长弱,存活率低.pH值7和8时,发病率较低,pH值9时没有发病,在pH值5和6时,植株生长良好,发病率也较高.表明根肿病菌侵染发病与温度、土壤pH值关系密切.

The pathogenicity difference of P. brssicae on cabbage were carried out under 7 different temperature and 6 different soil pH value with the resting spore concentration of 1 x l0s （speres/g） in the soil. The disease condition was investigated after 90 days. The results showed that there were different infection rates of clubroot ff cabbage among different temperature sets, the effect of temperature on the inci- dence of clubreot in descending order as follows ：30 ℃ 〉 25 ℃ 〉 20 ℃ 〉 35 ℃ 〉 15 ℃ 〉 10 ℃ 〉 5 ℃ under the pH value of 6, the infec- tion of clubfoot was weak and the infection rate was low under the temperature value of 5 ℃ and 10 ℃. The disease rate increased with in- creasing soil temperature under the temperature value of 5 - 30 ℃, but decreased at 35 ℃, the infection rates of clubreot were 80.36 %, 100 %, 65 %, 10.77 %, 3.23 %, 0 % under the soil pH 4, 5,6, 7, 8 and 9 at 25 ℃, respectively, the growth of cabbage was inhibi- ted and the survival rote was reduced under the pH value of 4, the infection rates of chibreot were low under the pH value of 7 and 8, and the infection rate of P. brassicae was 0 % under the pH value of 9. The Chinese cabbage grew better under the pH value of 5 and 6, but had the high infection rates of clubroot. The infection rate of clubroot was related to the temperature and soil pH closely.