[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.

[Relationships of wheat seed vigor with enzyme activities and gene expression related to seed germination under stress conditions.].

This study aimed to analyze the enzyme activities and gene expression differences related to seed germination in different wheat genotypes, and to clarify the relationship between seed vigor and the related enzyme activities as well as gene expression under stress germination conditions. We measured seed vigor, total soluble sugar content, soluble protein content, α-amylase activity, cysteine protease activity and gene expression of the related enzymes of four wheat cultivars under drought, artificial aging and cold soaking stress. Results showed that drought, artificial aging and cold soaking stress affected seed vigor to some extent.

[Seed vigor evaluation based on adversity resistance index of wheat seed germination under stress conditions.].

A total of 16 wheat cultivars were selected to detect seed vigor of different genotypes using standard germination test, seed germination test under stress conditions and field emergence test. The adversity resistance indices of seed vigor indices and field emergence percentage under different germination conditions were used as the indices to evaluate adversity resistance. Principal component analysis and cluster analysis were used for the comprehensive evaluation of seed vigor.