Effects of Daylength, Temperature and Nitrogen Level on the Heading of Rice Plants under the Controlled Environments

[摘要] The heading response of rice plants to daylength, temperature and nitrogen level was analysed under controlled environments in phytotron. 1. The heading response of rice plants (japonica) to temperature depended on daylength, and on the other hand, the response to daylength depended on temperature. The photo-sensitivity became duller under high temperature and more conspicuous under low temperature condition. These results indicated that the expression of thermo- and photo-sensitivity in heading response of a certain strain may vary with alternative conditions. 2. Nitrogen levels of culture medium did not influence on the growth duration from sowing to heading. No interaction was observed between nitrogen level and temperature or daylength in the heading response. 3. Under short day condition the sensitivity to temperature did not differ between early and late strains. But that of late strains was affected more strongly than early ones under long day condition. The heading of early strains was not affected by daylength under high temperature but affected slightly by daylength under low temperature. The heading of late strains was affected by daylength under high temperature, while it was more affected by daylength under low temperature than under high temperature. 4.These results may suggest that the rice plants in high latitudes have been lowered in the heading responsibility to daylength and growth temperature at several steps of the breeding Process

[学科分类] 农业科学（综合）