避雨栽培对葡萄霜霉病菌孢子囊飞散时空动态的影响

Effect of Rain-Shelter Cultivation on Temporal and Spatial Dynamics of Airborne Sporangia of Plasmopara viticola

【目的】葡萄霜霉病是葡萄生产上最重要的病害之一,在多雨潮湿地区常造成严重的产量损失。研究旨在明确避雨栽培对葡萄霜霉病菌(Plasmopara viticola)孢子囊飞散的影响,确定孢子囊飞散与病情变化之间关系,揭示避雨栽培对病菌数量的控制作用,推测避雨栽培下霜霉病的初侵染来源,为葡萄霜霉病的科学防控提供理论依据。【方法】2013年生长季7—9月份,分别对沈阳地区露地和避雨栽培小区内葡萄霜霉病发病情况进行定株定枝系统调查,统计得到病叶率和病情指数。应用SPSS19.0中回归曲线估计程序构建葡萄霜霉病流行时间动态模型,获得能描述不同栽培模式下葡萄霜霉病发病动态的模型参数,并推导2种栽培模式下霜霉病流行时期和流行速率。通过对田间小区内的孢子囊飞散进行定期监测,对比不同栽培模式下孢子囊飞散时间动态差异,探索关键流行时期内病害流行速率与捕孢量之间的关系。对比分析避雨栽培对葡萄霜霉病孢子囊水平、垂直方向飞散的影响,明确关键流行时期内孢子囊的主要来源和孢子囊飞散的主要影响因素。【结果】避雨和露地栽培下葡萄霜霉病的季节流行曲线趋势一致,均表现为典型的S形曲线。应用SPSS19.0软件分析,明确了Logistic模型能够反映沈阳地区葡萄霜霉病流行时间动态情况。露地和避雨栽培下病害流行时期:指数增长期分别为7月5—23日和8月18—30日,逻辑斯蒂增长期分别为7月23日至8月19日和8月30日至9月17日,衰退期分别为8月19日至葡萄生育末期和9月17日至葡萄生育末期。露地栽培下整个生长季孢子囊飞散表现为多峰曲线,当日降雨对孢子囊飞散有显著的冲刷作用。沈阳地区露地和避雨栽培下孢子囊飞散盛期分别为7—8月和8—9月。避雨栽培可明显降低空中孢子囊数量,从而减少孢子囊与避雨设施内葡萄叶片的接触概率,达到降低菌源基数的作用。避雨设施边行最早捕获孢子囊,且数量最多,随着逐渐向中心靠近,首次捕孢时间逐渐推迟,数量逐渐降低。葡萄叶幕对于孢子囊水平方向的飞散具有显著的阻隔效应。不同栽培模式下均以接近地面处的捕孢量最大,且随着高度增加,捕孢量逐渐减少。避雨设施对于接近棚顶处的孢子囊飞散有着显著的遮蔽作用。【结论】避雨栽培可推迟葡萄霜霉病始发时间和首次捕孢时间,缩短病害流行过程和孢子囊飞散周期,显著降低病害流行程度和孢子囊飞散数量。孢子囊飞散受到葡萄叶幕和避雨设施显著的阻隔效应。避雨栽培下葡萄霜霉病的初侵染主要为本地露地栽培下葡萄霜霉病病株上的病斑产生的孢子囊。

【Objective】 Downy mildew, caused by Plasmopara viticola, is the most serious disease in grape. Severe yield losses are caused wherever the weather during the growing season is humid and rainy. The objective of this study is to understand the effect of rain-shelter cultivation on airborne sporangia of P. viticola, define the relationship between airborne sporangia and changes of disease index, reveal the control of rain-shelter on the pathogen source, determine the control of rain-shelter on the pathogen source, analyze the primary infection sourced under the cultivation and provide a basis for formulating comprehensive control of the disease.【Method】Form July to September during 2013, the diseased leaf and disease index on the same shoots were investigated under rain-shelter and open-field cultivation, respectively. The data were used to fit the regression models of dynamic of grape downy mildew under the two cultivations by regression curve estimation in SPSS19.0, the epidemic phases and rate of the disease were derived based on the data. The sporangia of P. viticola were investigated under rain-shelter and open-field cultivation. The dynamics of airborne sporangia were compared under two different cultivations, the relationship between airborne sporangia and changes of disease index in the key epidemic phase were analyzed. The main source of sporangia in the key epidemic phase and the main influence factors of airborne sporangia were cleared by comparing the effect of rain-shelter on the horizontal and vertical sporangia dispersal.【Result】The seasonal epidemic curves of grape downy mildew under rain-shelter and open air cultivation were typical single peak S curve. The logistic model could reflect the temporal dynamic of grape downy mildew well by using SPSS19.0. The epidemic phases under the two cultivations, the exponential phases were from July 5th to July 23rd and August 18th to August 30th.The logistic phases were from July 23rd to August 19th and from August 30th to September 17th. The degenerating phases were from August 19th to the end of grape growing season and September 17th to the end of grape growing season. The seasonal airborne sporangia under open-field cultivation were a multi-peak curve. The daily rainfall had significant effects on the concentration of airborne sporangia. The peak periods were July to August and August to September under the two cultivations. Rain-shelter cultivation significantly reduced the number of airborne sporangia, thereby reduced the contact probability of sporangia and grape leaves in shelter facilities, and achieved the goal of reducing basic number of germs. Sporangia were trapped earliest on border row of the shelter facilities. The first trapped time delayed, and the concentration of airborne sporangia diminished with the closer to the center. Grape leaf canopy had significant barrier on airborne sporangia in horizontal direction. The concentration of airborne sporangia diminished with the increase of height under the two cultivations. There was a significant barrier effect of rain-shelter facilities on the airborne sporangia close to the roof.【Conclusion】The first visibility of the disease and the first trapped time of airborne sporangia were significantly delayed, the epidemic process of the disease and cycle of airborne sporangia were significantly shortened, epidemic degree of the disease and airborne concentration of sporangia were significantly reduced by rain-shelter facilities. There were significantly barrier effects on both rain-shelter facilities and grape canopy. The sporangia matured on the spot under open-field cultivation, discharged in rain and dispersed with airflow, finally provided main inocula for the epidemic of the disease under rain-shelter cultivation.