Effects of chilling stress on proline and soluble sugar content of Melilotus ruthenicus and He-tian alfalfa

In the low temperature stress(-4 ℃) and the gradient at different times(24 hours,48 hours,72 hours),the seeds of flat ruthenica and He-Tian alfalfa samples were used to study the changes of free proline and soluble sugar content.The results showed that under low temperature stress,flat ruthenica free proline and soluble sugar content showed an upward trend.Indicating flat ruthenica adapts to the absolute low temperature stress by increasing the seed of free proline and soluble sugar content to,reduce the low-temperature injury.Free proline content of alfalfa seed first increased and then decreased,and the absolute content of soluble sugar gradually increased.Evidence from this study further proved free proline and soluble sugar could be used as a physiological and biochemical indexes of plant cold-hardiness.By comparing the performing of the two varieties,a suitable one for plateau region can be selected.