| Grape (Vitis vinifera) is a deciduous plant,with the title of "god" of fruit.Grape production is 623900 tons,in Jiangsu province,ranked seventh national grape production. Jiangsu province is located in the lower reaches of the Yangtze River, the summer rainfall is larger,the climate of high temperature and high humidity conditions conducive to the happening of the disease, the serious influence planting grape growth and quality. In this study, we used the "red reference" as the research object, using the control experiment to determine the spectral characteristics of the grape leaves, chlorophyll content, the establishment of grape downy mildew disease index of the spectral monitor:ing model.The meteorological indexes of grape downy mildew are established .Collect facilities microclimate data of the growth period of grape, then the microclimate forecasting model of grape growing facilities is established, and the grading theory of grape downy mildew is forecast. The results provided the decision support for the meteorological support service of grape downy mildew. The main findings are as follows:(1)In the range of 400-700 nm, the canopy reflectance of plants infected by disease was higher than that of normal grape plants. The spectral reflectance of downy mildew was different in visible light (400-700nm) to near infrared (700-1000nm)band with the exacerbations of the disease showed an upward trend. The results of the first order differential spectroscopy showed that the red edge slope was reduced and the red edge position was "blue shift" in the red edge (680-780nm), which showed the characteristic spectrum of the disease. Under the condition of downy mildew, the differences of chlorophyll a, chlorophyll b and chlorophyll content in grape leaves were significantly different from those of normal plant samples, and the photosynthetic pigment content decreased gradually with the increase of severity.Using the spectral red edge parameters, the diagnosis model of leaf chlorophyll content was established.We selected the sensitive band related to downy mildew disease index, and established the spectral detection model of grape downy mildew disease index.(2)Based on the data of indoor and outdoor meteorological observation of greenhouse and greenhouse in Nanjing and Zhenjiang, the forecasting model of daily mean air temperature and daily mean relative humidity in different seasons constructed by stepwise regression method and BP neural network method were used.The daily mean temperature prediction results and the measured results were generally within 1 ℃. The daily mean air relative humidity prediction results and the measured results were generally less than 4%, and the model has good accuracy.(3)The development of grape downy mildew in plastic greenhouse was studied by indoor artificial climate box. The occurrence and development of grape downy mildew under different temperature and humidity combinations were investigated.The results showed that the relative humidity in the environmental conditions, the temperature at 20-25 ℃ when the occurrence of downy mildew and epidemic. The temperature was too high or too low, too low humidity will slow down the prevalence of downy mildew. According to the prediction results of temperature and relative humidity in the greenhouse, the meteorological grade prediction model of grape downy mildew occurrence and development was established.(4)According to the prediction results of temperature and relative humidity in the greenhouse, the grading model of grape downy mildew occurrence was forecasted.The model was used to calculate the grading of grape downy mildew in the greenhouse in January to August. And the actual occurrence of the number of days accounted for 79.5% of the total number of samples, consistent with the actual situation, the results for the facilities grape downy mildew weather forecast service to provide decision support. |
PDF Full Text Request