Effect of Seed Soaking with Exogenous Proline on Seed Germination of Rice Under Salt Stress

To explore the germination mechanism of salt-stressed rice improved by exogenous proline, and provide a theoretical basis to rice direct sowing technology for salinized soil, the effects of soaking with proline on germination status, amylase activity and isoenzyme were studied in this paper. The results showed that germination status including germination energy(GE), germination rate(GR), relative germination energy(RGE) and relative germination rate(RGR) significantly decreased as the same as the activities of alpha-amylase, beta-amylase and the total amylase under salt stress. Soaking with exogenous proline improved the germination status of rice under salt stress. Moreover, GE and RGE of salt-stressed rice were improved with increasing of proline concentration at the range of 5-45 mmol ·L-1. Soaking with 15 mmol ·L-1 and 30 mmol ·L-1 proline significantly improved the amylase activities(e.g. alpha-amylase, beta-amylase and total amylase) of rice under salt stress. Salt stress inhibited the express of beta-amylase isoenzyme temporarily, but had few impacts on alpha-amylase isozyme. Soaking with 30 mmol ·L-1 proline brightened District I and increased the width of ’i’ brand in District II of alpha-amylase isoenzyme, but had few impacts on beta-amylase isoenzyme. In a word, soaking with proline could effectively alleviate the inhibitory effects of salt stress on seed germination.