Understanding seed germination of forage crops under various salinity and temperature stress

Cool-season forage crops Alfalfa (Medicago sativa L.), Red clover (Trifolium pratense L.), Tall fescue (Festuca arundinacea Schreb.), Timothy grass (Phleum pratense L.) are economically beneficial to producers because biologically fixed nitrogen reduces the expenses. Soil salinization is the consequence of physical factors, population growth, economic pressure for more food production, and climate change impact that can be related to agricultural management practices. In forage crops, salinity and temperature stresses are primarily reducing the yield and limiting successful growth. This study aimed to investigate the effects of temperature and salinity in seed germination and determine optimum temperature and salinity for these cool-season forage crops. The results indicated that seed germination occurred over a wide range of salinity (from 0 to 100 mM NaCl) and temperatures (from 15 to 30 °C) with the highest germination between 0 and 25 mM NaCl at 15 to 20 °C. In M. sativa, salinity treatments were not different at 20 °C but the effect of high salinity concentration was more pronounced at low temperatures in T. pratense. For F. arundinacea and P. pratense, the salinity effect was moderate and the main factor for the germination was the temperature. Further, ungerminated seeds were transferred to distilled water after 20 days, and it occurred the highest recovery in 100 mM NaCl at 20 °C but seed recovery was low at 30 °C. The forage crops were able to germinate in moderate salt conditions and germinate as normal when the salinity conditions were removed but under optimum temperatures.