考虑日光温室空间异质性的黄瓜叶片湿润时间估算模型研究

Estimation Model of Cucumber Leaf Wetness Duration Considering the Spatial Heterogeneity of Solar Greenhouse

叶片湿润时间(LWD)是植物病害模型的重要输入变量之一,它与许多叶部病原菌的侵染有关,影响病原侵染和发育速率。为了准确地预测日光温室黄瓜病害的发生时间和方位,本研究于2019年3月和9月在北京两个不同类型日光温室内按照棋盘格法设置了9个采样点部署温湿光传感器和目测叶片湿润时间,每隔1 h采集一次温度、湿度、辐射和叶片湿润数据进行定量估算分析。分析结果表明:BP神经网络模型在两个温室的试验条件下获得了相似的准确度(ACC为0.90和0.92),比相对湿度经验模型估算叶片湿润时间的准确度(ACC为0.82和0.84)更高,平均绝对误差MAE分别为1.81和1.61 h,均方根误差RSME分别为2.10和1.87,决定系数R2分别为0.87和0.85;在晴天和多云天气条件下,叶片湿润时间的空间分布总体规律是南部>中部>北部,南面是叶片湿润平均时间(12.17 h/d)最长的区域;由东向西方向上,叶片湿润时间的空间分布总体规律是东部>西部>中部,中部是叶片湿润平均时间(4.83 h/d)最短的区域;雨天的叶片湿润平均时间比晴天和多云长,春季和秋季分别为17.15和17.41 h/d。这些变化和差异对温室黄瓜种群水平方向的叶片湿润时间分布具有重要影响,与大多数高湿性黄瓜病害的发生规律密切相关。本研究为预测温室黄瓜病害分布提供了有价值的参考,对控制病害流行和减少农药使用具有重要意义,提出的区域化分析温室内叶片湿润时间的方法,可以为模拟日光温室叶片湿润时间的空间分布提供参考。

Leaf wetness duration(LWD)is one of the important input variables of plant disease model,which is related to the infection of many leaf pathogens and affects the pathogen infection and developmental rate.In order to accurately predict the occurrence time and location of cucumber diseases in solar greenhouse,nine sampling points were set up in two different greenhouses located in Beijing in March and September 2019,according to the chessboard method to deploy temperature,humidity and light sensors.The fixed-point visual inspection method was used to collect the data every 1 h.From the leaf wetting to the leaf drying is the leaf wetness duration of a day.The relative humidity model(RHM)and back propagation neural network model(BPNN)were used to quantitatively estimate and analyze the LWD,the input layer of BPNN was temperature,humidity,radiation and location,the hidden layer was 10,and the output layer was location and whether the leaf surface was wet.The results showed that BPNN obtained similar accuracy ACC=0.90 and 0.92 under the experimental conditions of two greenhouses,which was higher than RHM ACC=0.82 and 0.84 in estimating of LWD,the mean absolute errors MAE were 1.81 h and 1.61 h,root mean squared error RMSE were 2.10 and 1.87,and coefficient of determination R2 were 0.87 and 0.85.In sunny and cloudy conditions,the spatial distribution of LWD was generally in the South>the Middle>the North.In the South,the average LWD was the longest,12.17 h/d;from the east to the west,the spatial distribution of LWD was generally in the East>the West>the Middle.In the Middle,the average LWD was the shortest of 4.83h/d.The average LWD in rainy days was longer than that in sunny days and cloudy days,the average LWD in spring and autumn rainy days were 17.15 h/d and 17.41 h/d.These changes and differences had an important impact on the distribution of leaf wetness duration in the horizontal direction of cucumber population in greenhouse,which was closely related to the occurrence rule of most high humidity cucumber diseases.In this research,the method of regional analysis of the wet duration of cucumber leaves in greenhouse was proposed,which could provide a reference for simulating the spatial distribution of LWD in greenhouse,and also had a certain reference significance for the establishment of cucumber disease early warning system.