紫花苜蓿和羊草种子出苗和幼苗生长对土壤含水量的响应

Responses of seed germination and seedling growth of Medicago sativa and Leymus chinensis to soil moisture

土壤含水量是种子萌发和幼苗生长阶段的关键环境因子。采用室内模拟方法,研究了不同土壤含水量(2.5%、5%、7.5%、10%、20%和30%)对紫花苜蓿和羊草种子出苗和幼苗生长的影响。结果表明:苜蓿和羊草种子的出苗率和幼苗的生长均显著受土壤含水量的影响;随着土壤含水量的增加,苜蓿和羊草的出苗率均呈先上升后下降的趋势;其中,苜蓿种子在土壤含水量为10%~20%时出苗率最高(93%),土壤含水量为30%时最低(2%);在5%土壤含水量时羊草出苗率最大(76%),在30%含水量时最低(9%);随着含水量增加,紫花苜蓿和羊草幼苗根苗长均表现为先上升后下降的趋势,土壤含水量7.5%~10%更适宜于紫花苜蓿种子出苗及幼苗生长,羊草种子的最适土壤含水量为5%~7.5%;综合出苗率和幼苗的生长情况,适宜苜蓿和羊草播种和幼苗生长的土壤水分含量分别为7.5%~10%和5%~7.5%。

Soil moisture is a key environmental factor affecting seed germination and seedling growth. To investigate the effects of soil moisture on seedling emergence and growth of Leymus chinensis andMedicago sativa under natural conditions, a simulation study was conducted with six soil moisture levels （2.5%, 5%, 7.5%, 10%, 20% and 30%）. The results showed that the seedling emergence rate and seedling growth of both species were significantly affected by soil moisture. With increasing soil moisture, the seedling emergence rate was first increased and then decreased. ForM. sativa, the seedling emergence rate was the highest （up to 93%） when the soil moisture was 10%-20%; the lowest seedling emergence rate was 2% at 30% soil moisture level. For L. chinensis, the highest seedling emergence rate was 76% when the soil moisture was 5%; the lowest rate was 9% at 30% soil moisture. With the increases of soil moisture, root length and seedling height first increased but then decreased, which was consistent with the pattern of seedling emergence rate. The optimal soil moisture level was 7.5%-10% for seedling emergence and growth of M. sativa, and 5%-7.5% for that ofL. chinensis seeds. In conclusion, soil moisture at 7.5%-10% would be suitable to the sowing and seedling growth of M. sativa, and 5%-7.5% for L. chinensis.