Plant Temperature and Its Simulation Model of Thermo-Sensitive Genic Male Sterile Rice

Abstract

Plant temperature ( T p) and its relations to the microclimate of rice colony and irrigation water were studied using a thermo-sensitive genic male sterile (TGMS) rice line, Pei'ai 64S. Significant differences in the daily change of temperature were detected between T pand air temperature at the height of 150 cm ( T A). From 8:00 to 20:00, T p was lower than T A, but they were similar during 21:00 to next 7:00. The maximum T p occurred one hour earlier than the maximum T A, though they both reached the minimum at 6:00. T p fluctuated less than T A. At the same height, during 6:00–13:00, T p was higher than air temperature ( T a), and T p reached the maximum one hour earlier than T a. During the rest time on sunny day, T pwas close to or even a little lower than T a. On overcast day, T pwas higher than T a in the whole day, and both maximized at the same time. In addition, T pwas regulated by solar radiation, cloudage and wind speed in daytime, and by irrigation water at night. The present study indicated that a T A of 29.6°C was the critical point, at which T pwas increased or decreased by irrigation water. T p and the difference between water and air temperatures showed a conic relation. T p fluctuation was also regulated by the absorption or reflection of solar radiation by leaves during daytime and release of heat energy during nighttime. By analysis on correlation and regression simulation, two models of T p were established.