Physiological significance of ABA and 4PU-30 in alleviating high temperature stress injury in Kentucky bluegrass

In order to explore the physiological mechanism of high temperature injury to cool-season turfgrass and regulations by exogenous plant growth substance,the effect of high temperature [(42.0±0.5)℃] on some physiological indexes in the seedlings of Total Eclipse(Poa pratensts L.)and the regulations of ABA and 4PU-30 were studied.The results showed that electrolyte leakage and malondialdehyde(MDA) content in seedlings increased significantly under high temperature stress,while the activities of superoxide dismutase(SOD) and the contents of soluble protein and glutathione(GSH)decreased significantly.The contents of soluble sugar,proline and ascorbic acid(AsA)increased slightly on day 2 under high temperature stress,but decreased significantly afterwards.The exogenous ABA(10 mg/L)and 4PU-30(10 mg/L) could slow down effectively the increase of electrolyte leakage and MDA content in seedlings during high temperature stress and the decrease of SOD activities and the contents of AsA,GSH,proline,soluble protein and soluble sugar in seedlings during the high temperature stress.