关键词: 轮耕, 主成分分析, 综合评价, 渭北旱塬

Abstract: Endogenous hormones are considered as a main internal cause to regulate germination and dormancy of seeds, which have been highly concerned. However, no theory or hypothesis on the change patterns of endogenous hormones with environmental changes and their regulation mechanisms on seed germination has been generally accepted. In this study, seeds of Halenia elliptica which is widely distributed in the alpine meadow of northeastern QinghaiTibet Plateau were used to test the dynamics of endogenous hormone content and germination under different storage temperatures and durations. The contents of endogenous hormones of seeds varied with storage duration under different storage temperatures. Under room temperature, the effects of storage duration on the absolute contents of endogenous hormones and the ratios of promoters to inhibitors (except IAA/ABA) were significant. Under cold storage, the effects of storage duration on the contents of GAs, IAA, ABA and total promoters were significant. Storage duration and storage temperature significantly influenced the germination percentage. The seed germination percentage under room temperature was about 4 times as high as that under cold storage, and seed germination showed a dormancy cycle. Seed germination of H. elliptica was not controlled by the contents of promoters or inhibitors. Seed germination correlated positively with the content of GAs and negatively with the content of IAA, while the germination percentage would be higher only when the CTK content was higher. Therefore, the relationships among endogenous hormones in this study might be consistent with the “threefactor” hypothesis proposed by Khan, that is, CTK antagonized ABA, to relieve or eliminate the role of ABA and promote the role of GAs.

Key words: rotational tillage, comprehensive assessment., Weibei Highland, principal component analysis