Abstract: A field experiment was conducted to investigate the effects of different drainage times during yellow ripening stage of rice on soil salt contents,Na contents in rice shoot, and rice grain yields on a coastal saline soil in Zhejiang province. The results showed that during yellow ripening stage of rice, the soil salt contents increased with soil depth. After drainage, salt contents in 0-80 cm soil depth showed a rising trend, which was resulted from the earlier drainage. However, change in salt contents in 80-100 cm depth was not great. Na contents in shoots of rice in earlier drainage treatment were higher than that in later drainage treatments. Compared to the treatment of conventional drainage time (October 7th), rice grain yield in the treatment of advancing drainage for 12 days decreased by 8.2%. Rice grain yield in treatment of delaying drainage for 14 days increased by 18%, and number of filled grains per panicle and grain weight of rice also significantly increased. However, there was no significant difference in rice grain yields between the treatments of delaying drainage for 29 d and 14 d. Therefore, delaying drainage for 14 days during yellow ripening stage of rice was an effective way to conform the stable yield of rice on a coastal saline soil.

Key words: saline soil, soil salt content, deferred drainage, rice field