Abstract: Yayou 2, one of hybridized combinations of Indica/Japonica, belongs to medium rice varieties. Its response to temperature is larger than that to photoperiod. The response of growth duration to nitrogen is next to that to temperature, and the effect of day length is the smallest. Their direct path coefficients are 0. 5209, -0. 5756, and 0. 3067, respectively. Yayou 2 is more sensitive to lower temperature at the reduction division stage and the heading-flowering stage, and its suitable temperature is remarkablely higher than that of Indica rice cultivars with weaker resistance to coldness; however, its resistance to high temperature is stronger than that of Indica rice varieties. Lower light intensity in heading-flowering period effects on spikelet fertility baddly, with the percentage of full grains being notably decreased. Therefore, high temperature and strong light are advantageous to increase in spikelet fertility and grain filling of the hybrid rice cultivar Yayou 2.

Key words: Rice cultivar Thermal-and photo-ecological characteristics, Rice cultivar Thermal-and photo-ecological characteristics