Abstract:Aiming to explore the pattern of crop canopy temperature change and spatial location distribution characteristics, so as to realize the reasonable deployment of the greenhouse temperature monitoring scheme to prevent the occurrence of local chilling injury of crops in solar greenhouses. A 40-channel high-precision temperature field monitoring system were deployed to collect the tomato canopy temperature in the winter in a northwest solar greenhouse. The Kriging interpolation algorithm was used to interpolate the collected data to obtain a temperature field model. And the temperature extreme value feature points of the temperature field model were obtained based on differential evolution (DE) algorithm. The spatio-temporal variations of canopy characteristic temperature under different weather conditions were analyzed. The results showed that the R2 values of interpolation in sunny, cloudy and overcast (rainy) days were more than 0.94, and values of the average root mean square error (RMSE) were 1.34℃, 0.95℃ and 0.40℃, respectively. The algorithm was more suitable for the interpolation of low temperature canopy temperature field in overcast (rainy) days and night. Under different weather conditions, the greenhouse canopy temperature showed a trend of higher west and lower east, higher inside and lower outside, and the overall change of the temperature in the greenhouse tended to be consistent in the overcast (rainy) days. After the exposure of sunny and cloudy weather, the indoor temperature distribution was quite different due to external light radiation, and the temperature decrease at night in sunny days was greater than that in overcast (rainy) days. The results of further analysis of the distribution of canopy extreme points showed that under different weather conditions, the distribution of extreme characteristic points in the solar greenhouse was basically the same, and the highest temperature points of the canopy mainly appeared near the middle of the greenhouse [22.0m, 2.5m]. The lowest temperature points mainly appeared near the outer film of the eastern part of the greenhouse [4.0m, 5.48m]. The acquisition of canopy extreme characteristic points in solar greenhouse provided a theoretical basis for greenhouse cultivation, temperature disaster monitoring and sensor deployment.
