Effects Of Heat Preservation And Water Treatment On Physiological And Biochemical Traits Of Zoysia Japonica Steud.under Winter Stress

Zoysiagrass has the advantages of beauty,trampling resistance,low maintenance cost and so on.Zoysiagrass is easily influenced by various environmental factors in the open environment.Especially before entering the dormancy period in low temperature and drought in winter.It entered the dormancy period earlier in the northern region,which restricted the further application of Zoysiagrass.At present,the lawn is heated by underground water heating,electricity heating and wind heating at home and abroad,so as to delay the withered and dormancy period of the lawn or make the lawn return to green early,so as to improve the application performance of the lawn,but there are problems of time-consuming,laborconsuming and money consuming.The stress physiology of Zoysiagrass mainly focused on the stress conditions of artificial low temperature and drought.However,the research under natural conditions mainly focused on the overwintering performance of Zoysiagrass.The physiological and biochemical response mechanism of winter stress of Zoysiagrass was not clear.‘Zenith'was used as the test material in this study.The heat preservation and combined with watering treatment(TW),watering treatment along(W),heat preservation treatment along(T)and non heat preservation and non watering treatment(CK)were carried out respectively.The changes of physiological and biochemical indexes of resistance,the percentage of withered and yellow leaves per unit area,electrical conductivity,the leaf relative water content,chlorophyll content,malondialdehyde,free proline,soluble protein,and the activities of SOD,POD,CAT and APX were measured under winter stress.In order to explore the response mechanism of Zoysiagrass to winter stress and explore a time-saving,labor-saving and money saving method to alleviate the winter stress of Zoysiagrass.The results showed that:(1)The ratio of withered and yellow leaves per unit area increased under winter stress,and the values of grass index and NDVI decreased gradually.Heat preservation(T)and watering(W)could reduce the decrease of grass index and NDVI under winter stress,reduce the speed of withered and yellow leaves,and delay the withered and dormancy period.On November 19,the ratio of withered yellow leaves per unit area(91.25%)was close to that of the control group(96.68%),and the NDVI value(0.300)of the water treatment(W)was close to that of the control group(0.295).The water content in the later stage of winter stress is no longer the main factor affecting the withering yellow of Zoysiagrass,but the main factor is temperature.(2)The electrolyte permeability and malondialdehyde content of Zoysiagrass increased continuously with the prolongation of winter stress time.With the continuous aggravation of low temperature and drought stress in winter,the cell membrane permeability,electrolyte permeability and cell membrane damage of Zoysiagrass increased.Both heat preservation and water treatment can slow down and postpone the growth trend of El and reduce the growth rate of malondialdehyde content.Before November 6,the mitigation effect of each treatment on the damage of cell membrane of Zoysiagrass under winter stress was: TW > W > T.After November 6,the mitigation effect of each treatment on the damage of cell membrane of Zoysiagrass under winter stress was: TW > T > W.(3)With the extension of winter stress time and the aggravation of the degree,the relative water content and chlorophyll content of Zoysiagrass leaf gradually decreased.Heat preservation(W)and watering(W)can reduce the speed of relative water content reduction and chlorophyll decomposition.The effect of TW is the best.(4)The content of osmoregulation substance of Zoysiagrass showed a significant change under winter stress.Proline content increased first and then decreased,soluble protein decreased.The leaf cells of Zoysiagrass after heat preservation(T)tended to synthesize and accumulate soluble protein rather than proline under winter stress.However,the proline and soluble protein of Zoysia japonica under water treatment(W)accumulated a lot,and the heat preservation and water treatment(TW)alleviated the damage of Zoysiagrass under winter stress.(5)The activities of antioxidant enzymes of Zoysiagrass had significant changes under winter stress,and the trends of SOD,POD,CAT and APX activities were different under different treatments.The changes of antioxidant enzymes in the control group showed that the four enzymes were more sensitive to winter stress.The response mechanism of antioxidant e to temperature and water was different in different stages of winter stress.In the early stage of winter stress,the effect of water on antioxidant enzyme activity was greater than that of temperature,and in the later stage of winter stress,the effect of temperature on antioxidant enzyme activity was greater than that of water.In conclusion,temperature and water factors played different roles according to different stages of winter stress.In the early stage of winter stress,water played a greater role than temperature,and in the late stage of winter stress,temperature played a greater role than water.Both heat preservation and watering can alleviate the winter stress of Zoysiagrass,and TW has the best relief impact on winter stress,which could keep heat and green,and delay the time when Zoysiagrass enters the dormancy period.