Abstract: To understand the adaptability and ion regulation mechanisms of Medi cago sativa, Melilotus officinalis, and Astragalus adsurgens seeds at thei r germination stage to saline environment, the seeds were treated with different concentrations of NaCl, and their germination rate and recovery germination rat e were determined. In the meantime, the changes of main ions contents in seed em bryos and the water uptake by the embryos at 400 mmol·L-1 of NaCl were in vestigated. At 50 mmol·L-1 of NaCl, the final germination rate of M. sativa seeds was obviously inhibited and decreased; while at 300 mmol·L-1 of NaCl, the final seed germination rate of M. officinalis was obviously hi gher than that of M. sativa and A. adsurgens, and the initiation of seed germination process of A. adsurgens was 5 days later than that of M. sati va and M. officinalis. M. sativa seeds rarely germinated at 400 mmol·L -1 of NaCl. After treated with 400 mmol·L-1 of NaCl for 1, 2, and 4 days, the water uptake by the seeds of test three species was obviou sly inhibited. The recovery seed germination rate of M. sativa was lower tha n that of the other two species, and the seed embryos of M. sativa accumulat ed more Na+ but leaked out more K+ and Ca2+. In saline environment, th e impact on the seed germination of the three species was due to osmotic stress and ion toxicity, but the physiological adaptation mechanisms differed with diff erent leguminous species seeds.

Key words: Rice germplasm, Relay seeding technique, Allelopathy, Field evaluation, Agronomic characteristics