Germination and water absorption responses of seeds of four vegetables under salt stress

摘要

The salt tolerance of glycophytes has been widely studied. They can be classified as tolerant, moderately tolerant, moderately sensitive, or sensitive on the basis of their production under salt stress. However, salt tolerance varies among growth stages. Here, we focused on germination, as it affects subsequent growth and yield. We compared the germination percentages of four species with different tolerances to salt stress, bean (sensitive), cabbage (moderately sensitive), zucchini (moderately tolerant), and asparagus (tolerant), in 0, 50,100, 150, or 200 mmolL~f NaCl. Bean and cabbage germinated quickly in the control and NaCl treatments, although cabbage showed delayed germination at the highest salinity. Germination of zucchini and asparagus inthe NaCl treatments lagged behind that of the control. Therefore, we hypothesize that zucchini and asparagus seeds initially regulate their osmotic potential and then accelerate absorption of water before germination. There was no difference in seed water content of any species between the control and NaCl treatments until germination. Thus, salt stress imposed by NaCl does not inhibit water absorption by seeds. Our results indicate that changes in the germination percentage over time should be measuredin addition to the final germination percentage when salt tolerance during germination is assessed.