Effects of pre-sowing seed treatments on establishment of dry direct-seeded early rice under chilling stress

Mechanization and simplification are inevitable trends in agriculture production to decrease input demands and simultaneously improve resource use efficiency. Dry direct-seeded rice is a resource-saving cropping system and has been considered as a replacement for traditional transplanted rice. However, the poor establishment of dry direct-seeded early rice, primarily induced by chilling stress, has limited the wide adoption of this system. To examine the effects of pre-sowing seed treatments on rice germination, seedling growth and associated metabolic events under chilling stress, two seed coating treatments (Hanyubaomu coating and Miaoboshi coating) and two seed priming treatments (selenium priming and salicylic acid priming) were tested in field and growth chamber experiments. The results revealed that under chilling stress, seed priming increased the rice seed germination by 20.96-26.31 %. The length and weight of shoots and roots were also significantly increased. The two seed coating treatments were not effective in enhancing seed germination and seedling growth under chilling stress. The improved germination and seedling growth of primed seeds under chilling stress were strongly linked with higher α-amylase activity and total soluble sugar content. Conclusively, these findings will provide new avenues for understanding and advancing pre-sowing seed treatments of dry direct-seeded early rice.