The Effect Of Exogenous Glycine Betaine Application On Drought Tolerance Of Creeping Bentgrass

To explore the effects of exogenous glycine betaine (GB) on the basic physiological indicators, osmotic adjustment system and antioxidant system of creeping bentgrasss (Agrostis stolonifera) species ’T-1’ under different water conditions, creeping bentgrass sods were transplanted into a greenhouse and grown for 50 days before spraying GB with 4 concentrations (0,50,100 and 200 mmol/L). One group applied artificial drought treatment and rehydration after 3 days of GB application, and another group was well-watered. The goal was to research the exogenous GB could increase drought resistance of creeping bentgrass and its physiological mechanisms, so as to provide new ways to improve turfgrass adaptation to drought stress and water conservation of golf course and urban green space.By determination physiological and biochemical indicators, the results showed that application of low (50 mmol/L) and moderate (100 mmol/L) concentrations of GB significantly reduced the decline of turf quality, relative water content, and chlorophyll contentin creeping bentgrasss under drought stress when compared with drought stressed without GB. They also decreased electrolyte leakage, malondialdehyde content, superoxide anioncontent and hydrogen peroxide content, but increased the free-proline content, soluble protein content, endogenous betaine content and activity of betaine aldehyde dehydrogenase (BADH), SOD and CAT during drought stress, but no effected on POD. After rehydration, low and moderate concentrations of GB treated plants recovered in all physiological parametersto pre-stressed level. In addition, application of low and moderate increased turf quality, chlorophyll content on creeping bentgrass under well-watered condition, and a certain role in promoting soluble protein content, but had no effect on other indicators. However, high (200 mmol/L) concentration of GB significantly reduced turf quality, relative water content, and increased electrolyte leakage, malondialdehyde content, superoxide anion content and hydrogen peroxide content, had a negative impact on growth of creeping bentgrass. These results suggested that application of low and moderate concentrations of exogenous GB could enhance the drought tolerance of creeping bentgrass under drought stress, and more capability was accumulated by creeping bentgrass to defense drought stress after rehydration. Turf quality of creeping bentgrass was also improved by low and moderate concentrations GB under normal growth conditions and the optimum concentration was 100mmol/L. It is, therefore, concluded that GB-enhanced drought tolance in creeping bentgrass possibly resulted in maintenance of osmotic adjustment to preserving intracellular water and elevated SOD, CAT acivity to reducing oxidation of membrane lipid.