Abstract:

The germination process in Medicago sativa seeds is influenced by various factors， among which salt stress is a key limiting factor. There is widespread interest in application of the emerging plant growth promoter diethyl aminoethyl hexanoate （DA-6） in agricultural production， but there is no clear research report on its specific mechanism of action on alfalfa seed germination under salt stress conditions. Consequently， this investigation examined the impact of a 150 mmol·L^-1 NaCl environment on the development of alfalfa seeds when subjected to DA-6 concentrations of 2.5， 5.0， 10.0， and 15.0 mmol·L^-1. Specifically， our analysis focused on the effects of DA-6 immersion on alfalfa seedlings at both the sprouting and the initial plant formation stages. The findings revealed a substantial decrease in the vitality of M. sativa seeds and a marked suppression of their ability to germinate under conditions of high NaCl concentration. Seed soaking treatment with DA-6 at various concentrations increased the germination rate， germination index， germination potential， root length， stem length， fresh weight and dry weight， and improved the seed germination. The 2.5 mmol·L^-1 DA-6 seed soaking treatment increased the activity of antioxidant enzymes in seeds under salt stress. The practice of immersing alfalfa seeds in DA-6 has thus been shown to augment alfalfa seedling resistance to salinity and to stimulate seed sprouting. This enhancement is attributed to an upsurge in the levels of accessible proteins， sugars， and free proline within the seeds. Multivariate analysis showed that the 2.5 and 5.0 mmol·L^-1 DA-6 concentrations had the most positive effect on alfalfa seed germination and seedling growth in an otherwise normal environment under NaCl stress.

Key words: Medicago sativa, diethyl aminoethyl hexanoate, NaCl stress