[Effects of soil water condition and microclimate on transpiration rate of rice]

The transpiration rate and water use efficiency (WUE) of rice were studied under high, moderate and low soil water conditions (treatments A, B and C) in the red soil area of southern China. Diurnal variation of transpiration showed that rice transpiration rate was influenced by several microclimatic factors in the field. Correlation analysis and stepping multi-regression analysis suggested that the difference of relative humidity between leaf and air, and the leaf temperature were the two main factors affecting the transpiration rate of rice. The results also showed that WUE was and yield were increased significantly in treatment B. While in treatment C, the WUE increased, but the yield of late rice decreased. The transpiration rate of early rice was decreased under moderate and low soil water treatments, but this did not happen to late rice.