Prediction of Rice Leaf Blast. III. Meteorological Variables and Percentage of Leaf Area Infected by Pyricularia oryzae

Abstract

利用復迴歸分析1979~1984年臺農67號之病斑面積率與氣象變數之間的關係，建立六個方程式來預測稻熱病在發病最高峰期之病斑面積率，並以1985年之氣象變數與病斑面積率數據來驗證此等預測方程式之準確性，結果顯示其各預測值與實測值之數據甚為接近，且依病斑面積率與產量損失之關係，預測值與實測值屬於同一級數。各預測方程式係以病斑面積率與其角度值為因變數分別求得的。分析的結果，顯示轉角與否並無顯著的差別。在所建立的預測方程式含有3~4個氣象變數，分別為平均相對濕度，相對濕度在90％以上之小時數，降雨量及降雨日數，預測方程式中R2之值為0.89~0.96。在六個預測方程式中，四個係由二月中旬的之氣象變數組成的，而其餘二個係由二月下旬之氣象變數組成的。 By using multiple regression to analyze the relationships between meteorological variables and percentage of leaf area infected by Pyricularia oryzae on rice cultivar, Tainung 67, six reliable predicting equations were derived. The equations derived from 1979-1984 were tested in 1985. The results shoved that the predicting values were close to the observed values. The predicting equations were obtained by using percentage of diseased leaf area with and without arcsin transformation. Equations derived from transformed and untransformed data were similar. The equations contained 3-4 meteorological variables, such as average RH, hours of RH over 90%, rainfall and rainy days. The coefficients of determination of the equations were 0.89-0.96. Among the six equations, four were derived from the meteorological variables of middle February, and the other two were derived from late February