Cold Tolerance of Hybrid Rice Liangyou 456 and Shanyou 456 Combined from Restorer Line R456 of Special Plant Type

It was tested to two new hybrids rice Liangyou 456 (mated from two line system male sterile 555S and restorer R456) and Shanyou 456 (mated from three line system male sterile Zhengshan 97A and restorer 456) in the provincial hybrid rice trial at 6 different areas of Guizhou. The autumn cold weather always occurred at the rice heading period in 3 high altitude sites especially at Guiyang site and it affect the seed setting rate and yield of some rice varieties. However, the seed setting rate and yield of Shanyou 456 (with seed setting rate 70. 07% and yield 7687. 95kg/ha) and Liang you 456 (with seed setting rate 75. 3% and yield 7357kg/ha) were higher than CK Shanyou 63 (with seed setting rate 64.3% and yield 4818kg/ha). It indicated that these two new hybrids were cold tolerant certainly.