Effects of saline and alkaline stresses in varying temperature regimes on seed germination of Leymus chinensis from the Songnen Grassland of China.

摘要

Leymus chinensis is a dominant and most promising grass species in the Songnen Grassland of Northern China. Experiments were conducted to determine the effect of temperature, salinity, alkalinity and their interactions on seed germination. Seeds were germinated at four alternating temperatures (10-20, 15-25, 20-30 and 25-35 degrees C), with saline stress (9:1 molar ratio of NaCl:Na₂SO₄) and alkaline stress (9:1 molar ratio of Na₂CO₃:NaHCO₃). Germination percentage and rate were inhibited by either an increase or decrease in temperature from the optimal temperature range of 20-30 degrees C, and were also inhibited by an increase in salinity and alkalinity at all temperatures. The inhibitory effects of high salinity on germination were greater at 25-35 degrees C, but seeds were subjected to more stress even though the alkalinity was low under this temperature. Recovery percentage was highest at 400 mM salinity at 20-30 degrees C, but only at 100 mM alkalinity, and 25-35 degrees C also resulted in lower recovery percentage under both stresses. Results suggest that saline stress and alkaline stress have different impacts on seed germination and that saline-alkaline tolerance of L. chinensis seeds is affected by the interactions of temperature and salinity-alkalinity. Early July sowing in the field is recommended when temperature is optimal and salinity-alkalinity concentrations are reduced by the high rainfall.