大棚黄瓜霜霉病发生与相对湿度的相关性

Study on Correlation between Occurrence of Cucumber Downy Mildew and Relative Humidity in Greenhouse

通过对大棚黄瓜霜霉病发病率、病情指数与相对湿度的相关性分析,结果表明,(1)日均相对湿度≥80%累计天数与发病率和病情指数呈显著的线性正相关,累计天数4～5d以内时,发病率≤20%,病情指数10左右;(2)相对湿度≥80%、≥90%逐时累计量与发病率和病情指数均呈线性正相关,且灵敏度相当,当相对湿度≥80%累计时数达到140h或≥90%累计时数100～110h时,霜霉病发病率达到20%左右,病情指数为10;当相对湿度≥80%累计时数达到450～500h或≥90%累计时数达到300h时,发病率达到100%,病情指数达到50;(3)5d新增病株率随相对湿度≥80%累计天数(时数)增加呈指数增长,5d新增病情指数与后者呈抛物线关系,当≥80%累计天数(时数)为14d(450h)时新增病情指数达到最大。

Through the correlation analysis of downy mildew （DM） of cucumber between the disease rate （DR）, disease index （DI） and relative humidity （RH） in greenhouse, the results indicated that： （1）the DR and DI had significant positive linear correlation with cumulative days of average RH ≥80%, when cumulative dates of 4-5, DRy≤20%, DI= 10; （2）the cumulative hours （CH） of RH≥ 80% and ≥90% had positive linear correlation with the DR and DI, and they had similar sensitivity, when CHRH≥ 80%= 140 h or CHRH≥90% =100-110 h, DRy20%, DI= 10; when CHRH≥80%=450-500 h or CHRH≥90%=300 h, DR=100%, DI=50; （3）the rate of new infection of 5 days grew exponentially with cumulative days （hours） of RH ≥ 80%, the increase of DI had a parabola relationship with the latter, when cumulation days （hours） of RH ≥ 80% was 14 d （450 h）, the increase of DI reached maximum.