**1. Introduction**

Temperature affects not only the growth rate, but also reproductive development of rice. When temperature was higher than a critical point value during 5-15 days before heading, rice thermo-sensitive genic male sterile (TGMS) line showed pollen sterility. Otherwise, it would be fertile (Lu *et al* 2001). The relationship between temperature and plant growth or reproductive development is usually studied by using a thermometer screen at a weather station placed at height of 150 cm (TA), although a few studies were also performed to describe more direct and accurate effects of micro-climate temperature at rice canopy on plant growth and reproductive development.

Plant temperature (Tp) is regulated by various factors including solar radiation, cloud cover, wind speed, soil heat flux, and transpiration of plant. Besides, temperature and flow velocity of irrigated water have significant effects on rice Tp. Many methods and simulations on Tp have been reported (Cellier 1993, Cui *et al* 1989, Ferchinger 1998, Hasegawa 1978, Leuning 1988a, 1988b, Lu *et al* 1998, Tetsuya *et al* 1982, Van *et al* 1989, Wei *et al* 1981, Zhao *et al* 1996). Tp was used as the index of water supply regime for wheat or corn (Cheng *et al* 2000, Huang *et al* 1998, Shi *et al* 1997, Yuan *et al* 2000), freezing injury or grain filling rate of wheat (Feng *et al* 2000, Li *et al* 1999, Liu *et al* 1992, Xiang *et al* 1998, Xu *et al* 2000). In recent studies, it was found that the fertility alteration of rice TGMS line was sensitive to Tp (Lu *et al* 2007, Xu *et al* 1996). Lu *et al* (2004, 2007) found that the sterility of TGMS was simulated more accurately by temperature at stem part of 20 cm height or air temperature (Ta) around the part when compared with TA at a weather station (Lu *et al* 2004, 2007, Zou *et al* 2005). So far, little is known about how Tp is regulated by microclimate or irrigated water (Hu *et al* 2006).
