虎尾兰水提取物对黄瓜霜霉病的防治研究

明确虎尾兰水提取物对黄瓜霜霉病菌无性阶段的抑制作用及对黄瓜霜霉病的防治效果。采用凹玻片法和离体叶五点接种法分别测定该提取物对游动孢子的释放和游动、休止孢的萌发和芽管伸长以及菌丝生长和孢子囊产生的抑制作用，采用离体叶五点接种法测定该提取物的保护作用、治疗作用和持效期，并采用盆栽试验测定该提取物的保护作用和治疗作用。一系列试验结果显示，虎尾兰水提取物对黄瓜霜霉病菌游动孢子的释放和游动，休止孢的萌发和芽管伸长以及菌丝生长和孢子囊产生的EC₅₀值分别为1.19、0.77、0.70、2.13、9.09和13.15 mg/mL。在离体叶片条件下，虎尾兰水提取物对黄瓜霜霉病的保护和治疗作用的EC₅₀值分别为3.69 和14.57 mg/mL，持效期达14 d以上。盆栽条件下，该提取物对黄瓜霜霉病保护作用和治疗作用的防效分别为68.38%和21.33%。虎尾兰水提取物对黄瓜霜霉病具有很好的保护作用和较长的持效期。

A study of snake plant water extract against cucumber downy mildew

The inhibitory effects on the asexual stage of Pseudoperonospora cubensis and the control effects on cucumber downy mildew of snake plant (Sansevieria trifasciata) water extract were clarified. The inhibitory effects of the water extract on the release and swimming of zoospores, germination and germ tube elongation of cystospores, hyphal growth and sporangium production were observed through concave slide method and in vitro leaf five-point inoculation method. The preventive effect, curative effect and effective duration of this extract were determined using the method of in vitro leaf five-point inoculation, and the preventive and curative effects of this extract were further verified by potted trial. The results showed that the EC₅₀ values of snake plant water extract to the release and swimming of zoospores, germination and germ tube elongation of cystospores, and hyphal growth and sporangium production were 1.19, 0.77, 0.70, 2.13, 9.09 and 13.15 mg/mL, respectively. Under the leaf in vitro conditions, snake plant water extract manifest preventive and curative effect with the EC₅₀ values of 3.69 and 14.57 mg/mL, respectively. The effective duration was more than 14 days. Under potted conditions, the protective and therapeutic effects of this extract were 68.38% and 21.33%, respectively. The experiments proves that snake plant water extract has a good preventive effect with a long effective duration on cucumber downy mildew.