大黄酚对黄瓜白粉病菌的抑制作用研究

Inhibitive effect of chrysophanol on Sphaerotheca fuliginea

采用子叶喷雾法分别测定了大黄酚（chrysophanol）对黄瓜白粉病菌（Sphaerotheca fuliginea）的保护和治疗生物活性。结果表明,大黄酚能有效降低黄瓜白粉病的病情指数,其保护和治疗作用的EC50分别为0.23μg/mL和25.88μg/mL,对照药剂50%硫磺悬浮剂保护作用的EC50为59.75μg/mL,10%苯咪甲环唑可湿性水分散粒剂治疗作用的EC50为13.55μg/mL。在此基础上,利用2.4μg/mL大黄酚溶液处理黄瓜子叶24h后接种白粉病菌,在不同时段对病组织进行透明染色观察白粉病菌的变化情况。结果发现,大黄酚可有效降低黄瓜白粉病菌分生孢子的萌发率和萌发芽管个数,并能抑制菌丝的生长以及降低新生分生孢子的个数。接菌后24h,清水对照萌发率为66.6%,而大黄酚处理后的孢子不萌发;接菌后48h,对照菌丝的平均长度为414.7μm,大黄酚处理的菌丝平均长度为40.1μm;接菌后144h,对照的新生分生孢子串最多为8个孢子,大部分为6-7个,而大黄酚处理后的新生分生孢子串孢子个数最多为2个,大部分为1个。接菌7d后对照的病情指数为72.2,大黄酚处理组的病情指数仅为2.1,其保护作用防治效果达到97.1%,远高于50%硫磺悬浮剂65.4%的防效。

The protective and curative effect of chrysophanol on the development of Sphaerotheca fuliginea were determined by cotyledon-spraying method.The results showed that chrysophanol effectively reduced the disease index,the protective and curative EC50 values were 0.23 μg/mL and 25.88 μg/mL respectively,while the protective EC50 for 50% Sulfur DF was 59.75 μg/mL and the curative EC50 for 10% Difenoconazole WG was 13.55 μg/mL.Inoculation was made on cucumber cotyledon 24 hours after treatment with chrysophanol at the concentration of 2.4 μg/mL.The detached leaf discs were cleared and stained and then the spore germination,mycelium growth and spore formation were observed.The results showed that chrysophanol depressed the growth of mycelia and reproduction of new conidia.The average germination rate was about 66.6% 24 h after inoculation in untreated control,while there was no germination in the treatment with chrysophanol.The average germ tuber length was about 414.7 μm 48 h after inoculation in untreated control,while only 40.1 μm in the treatment with chrysophanol.After inoculation for 144 h the maximum number of conidia linked in a chain was 8 with most of them between 6 to 7 in the control,while that was only 2 in chrysophanol treatment and most of them were 1.The disease index in cotyledon of cucumber was 72.2 in the control 7 days after inoculation,while that was only 2.1 in the treatment with chrysophanol.The protective control effect was 97.1% much higher than 65.4% of 50% Sulfur DF.