Bull. Spec. CORESTA Congress, Lisbon, 2000, p. 126, P6
Study on the predictive models of tobacco virus disease transmitted by aphids
Qingzhou Tobacco Research Institute of CNTC, Qingzhou, Shandong, China
In China, CMV, PVY and TEV transmitted by aphids have seriously impaired tobacco production in most tobacco-growing areas. In this paper, several predictive models, concerning aphid-transmitted tobacco virus disease, were formulated. Based on the related data in the period of 1980-1998, with monthly average temperature and rainfall, a long-range model was developed to predict tobacco virus disease transmitted by aphids in later June before sowing. Y=8.3846+0.6504X1+0.6585X3+14.4583X11+5.9063X12 ………………….…1. (X1-X8 is monthly rainfall between Oct. of the preceding year and May of the current year; X9-X16 is monthly average temperature between Oct. and May.)Model "1" can be used to predict the disease occurrence of the coming year before sowing. Mid-range models were produced according to the meteorological factors between October and May, transplanting date or population density of alatae during its peak of flight.Y=-99.0763+0.2211X1-0.0997X2-0.9018X6+5.8605X9+2.3756X10+9.9803X11+7.3108X12-0.9290X13+1.7195X16+1.6336X17 …………………………………….……….…2.(X17 is the days from Apr. 30 to transplanting date.) Using model "2", we can make a prediction to field disease index before transplanting. Y=-75.1930+0.7539X1+0.8089X3-0.0047X8+13.1134X9-9.2786X10+10.4861X12-1.5248X16+0.091X18…………………………………………………………..…3.(X18 is population density of alatae at their peak of flight.)Model "3" facilitated us to predict field disease index after the peak of aphid flight.The models were examined by T-test and showed the selected factors correlated to disease index at a significant or extremely significant level and the models significantly related to disease indexes.Fitting values and errors of samples using the three models, the rate of prediction accuracy was 83.29%, 98.60%, and 99.99% respectively. When predicting the year 1999, the rate of accuracy was 96.45%, 92.75%, and 93.39% respectively. This demonstrated the accuracy of the models.We can use the models to make a long-range prediction (year prediction) or a mid-range one (about 30 days).