Abstract:In order to rapidly identify the tolerance to low temperature of Desmodium intortum, the physiological response to low temperature stress (4℃) was studied by comparing with Macroptilium atropurureum, a high quality forage widely planted in southern provinces in China. The results showed that under low temperature stress, the effective quantum yield (Yield) and electron transfer rate (ETR) from the 2nd to 8th day decreased significantly in M. atropurureum than those in D. intortum (P<0.05). The superoxide dismutase (SOD) activity increased and catalase (CAT) activity decreased significantly (P<0.05) for both D. intortum and M. atropurureum under low temperature stress. Specifically, the decrease of CAT activity in D. intortum was lower than that in M. atropurureum. The peroxidase (POD) activity of D. intortum did not change (P>0.05) under low temperature, while POD activity in M. atropurureum decreased by 47.11%. The contents of free proline (Pro) and soluble sugar were significantly higher in D. intortum than those in M. atropurureum (P<0.05) under low temperature. According to regression analysis, resistance index and nutrient composition analysis, D. intortum was superior to M. atropurureum in cold resistance and nutritional value. Furthermore, Yield, ETR, CAT, Pro and soluble sugar of D. intortum could be used asimportant physiological indexes for identification of cold tolerance.
