针对我国南方稻区直播早稻发展较快，播种期相对提前，但苗期易遭受“倒春寒”低温冷害及伴随阴雨天气双重胁迫的影响，导致种子难出苗成苗，影响直播稻高效、稳产等突出问题，本项目以南方稻区早稻主栽品种为研究对象，基于人工气候箱自动控温和大田分期播种方法相结合，研究苗期低温冷害对直播早稻幼苗生长的影响，明确直播早稻品种苗期耐冷性生长差异及其敏感时期，提出和建立耐冷性评价指标并筛选出不同耐性品种；阐明不同低温耐性品种苗期低温冷害生长差异的生理及分子机理及适应机制，并进一步摸清湿度与低温耦合影响直播早稻幼苗生长的作用机制及其耦合效应；同时通过大田分期播种试验，探明直播早稻苗期低温冷害对产量及品质影响的后效应特性，建立灾害评估体系，并明确低温冷害下水、肥等措施的调控途径，构建直播早稻苗期低温冷害的防控技术，为南方稻区直播稻生产发展与高效稳产抗逆栽培提供理论依据。

The production of direct seeding-early rice (DSER) in double cropping had been rapidly developed in southern China, and the sowing date of DSER has been brought forward. However, DSER could be easily subjected to cold spell in later spring (CSLS) and CSLS accompanied with rainy weather combined stresses at early seedling stage, resulting in seedling difficult emergence and establishment and affecting grain yield in DSER. Therefore, based on the growth cabinet and field experiment at different sowing date, leading DSER varieties of southern China selected, could be studied the effects of different low temperature treatments on seedling growth at seedling stage. The objectives of this research are (1) to investigate its sensitive period response of low temperature, the difference in cold tolerance and screen out the test rice varieties; (2) to investigate the difference in physiology & biochemistry characteristics and molecular adaptive mechanism to response of different cold tolerance cultivars, to further elucidate the physiological and molecular mechanism and its interaction effect on seeding growth of DSER under wet and chilling combined stresses at early seedling stage. (3) to clarify the ultimate effect on grain yield components and quality characteristics under chilling damage at seedling stage, so as to establish the evaluation system of disaster damage, and further to propose the regulation approach of water and fertilizer managements, so as to establish the prevention and control technology on chilling damage at seedling stage of direct seeding rice. Our studies may provide a theoretical basis and technical support for the production of direct seeding rice and stable yield & efficient cultivation of DSER in future.