In the Yangtze river aera,the first crop of indi-ca rice is sown in late Mar to early Apr andtransplanted in early May.Usually,seedlingsperish when abnormal low temperature of 6-10℃ lasted for 3 d or longer.The effect ofsocking seed with urea solution on increasingthe cold tolerance at the seedling stage was In the Yangtze river aera, the first crop of indi-ca rice is sown in late Mar to early Apr and transplanted in early May. Usually, seedlingsperish when abnormal low temperature of 6-10 ° C lasted for 3 d or longer. The effect ofsocking seed with urea solution on increasingthe cold tolerance at the seedling stage was