[Changes of wheat seed vigor at different development stages and their response to environmental temperature].

Two wheat cultivars (Jimai 22 and Shannong 23) were selected to investigate the changes of seed vigor at different development stages in different years by standard germination test, and the effect of environmental temperature on it was also analyzed, which would provide a theoretical basis for the utilization of early wheat seeds and the production of high vigor seeds. The results showed that the germination ability of fresh seeds appeared around 26 d after anthesis, and then the germination rate of fresh seeds displayed an overall upward trend with the development of wheat seeds. The germination energy, germination rate and germination index of dry seeds rapidly increased from 5 d to 8 d after anthesis, and then remained relatively stable, while the vigor index increased continually and reached the peak 4-6 days before the end of ripening due to the increase of seedling dry mass. The dry seeds at different developmental stages were also studied by field-plan-ting and the seed vigor of their progenies was also determined. For Jimai 22, the results indicated that the field emergence of dry seeds at 17 d after anthesis was higher and the plant could form grains, there were no significant differences in germination rate and vigor index among different samples of progeny seeds. In addition, the changes of seed vigor at different development stages were significantly affected by the environmental temperature. In the year with the high mean daily average temperature, high mean daily maximum temperature, high mean daily minimum temperature after anthesis, and large mean daily temperature difference after anthesis, the seed development time was shorter, but the 100-grain mass and seed vigor reached the peak earlier; Otherwise, the seed development time was longer, but the accumulated temperature of ripe stage was higher, and the seed vigor was higher.