Physiological Response Mechanism Of Leymus Chinensis In Three Leaf Colors Under Nitrogen Addition And Saline-alkali Stress

Leymus chinensis is a perennial rhizomatous gramineous plant.Leymus chinensis has high protein content,mineral and carbohydrate content,and good palatability,it has good palatability and is the dominant grass species in Inner Mongolia grassland.Leymus chinensis is widely distributed in songnen plain of Inner Mongolia,western plain of liaohe river,Hulunbuir grassland and Xilingol grassland.Leymus chinensis grows in different soil types,and in the long-term adaptation to different growth environments,Leymus chinensis populations with different leaf colors are formed.In the distribution area of Leymus chinensis,gray-green and yellow-green Leymus chinensis can often be seen at the same time as the middle transitional color of the Leymus chinensis.At present,there is still a lack of in-depth study on the differences in the physiological responses between the three species of Leymus chinensis.Therefore,this paper takes gray-green,transitional color and yellow-green Leymus chinensis as research objects.Through the artificial simulation of nitrogen addition environment and saline-alkali stress environment,the physiological response mechanism of three species of Leymus chinensis was systematically studied,and three kinds of leaves were analyzed.It provided a theoretical basis for the scientific management and management of pasture.The results showed that the physiological and biochemical indexes of Leymus chinensis were different under three nitrogen treatment levels.Two-factor analysis of variance of physiological and biochemical indexes of Leymus chinensis with different leaf color under nitrogen treatment showed that most indexes reached significant(P<0.05)or extremely significant(P<0.01)levels.For plant height,number of plants,SPAD value,above-ground biomass,total biomass,nitrate nitrogen content,ammonium nitrogen content,soluble sugar content,soluble protein content,nitrate reductase activity,glutamine synthetase activity and glutamate dehydrogenase activity,under the treatment of nitrogen fertilizer,the different leaf color of Leymus chinensis had different degrees of increase compared with the control group.Under the same nitrogen application concentration,the three leaf color of Leymus chinensis showed a trend of gray green>transition color>yellow green.According to the response results of each index of the three leaf color Leymus chinensis to nitrogen treatment,under the simulated nitrogen deposition environment,grey-green Leymus chinensis has the strongest adaptability,followed by transitional Leymus chinensis,and yellow-green Leymus chinensis is the weakest.The results showed that the physiological and biochemical indexes of different leaf color Leymus chinensis varied to different degrees under four saline-alkali treatment levels.Two-factor analysis of variance of each physiological index of Leymus chinensis under different saline-alkali stress levels showed that most of the indexes reached the significant(P<0.05)or extremely significant(P<0.01)levels.For the plant height of Leymus chinensis,the plant height of three species of Leymus chinensis showed a decreasing trend with the increase of the intensity of salt-alkali stress treatment.Under each saline-alkali concentration,the plant heights of three species of Leymus chinensis showed a trend of gray green > transition color > yellow green.In terms of osmotic adjustment,the proline content,soluble sugar content and soluble protein content of three species of Leymus chinensis increased with the increase of the intensity of saline-alkali stress.For the antioxidant enzyme system,the activities of 7 antioxidant enzymes all increased to varying degrees with the enhancement of saline-alkali stress,Moreover,under the same saline-alkali concentration,the three leaf color Leymus chinensis showed a trend of gray green>transition color>yellow green.According to the response results of each index of the three leaf color Leymus chinensis to saline-alkali treatment,the grey-green Leymus chinensis has the strongest adaptability,the transitional Leymus chinensis is the second strongest,and the yellow-green Leymus chinensis is the weakest.