the enhancement of drought stress tolerance of kentucky bluegrass by prohexadione-calcium treatment

Kentucky bluegrass (poa pratensis l.) is one of the most widely usedturfgrasses for home lawns, golf courses, parks, and athletic fields intemperate climates. oxidative stress caused by drought stress is a majorlimiting factor for grass cultivation in arid and semi-arid regions. theobjective of this study was to investigate whether prohexadione-calcium(pro-ca) may play a role in promoting drought tolerance in kentuckybluegrass. pro-ca was exogenously applied as a foliar spray at the rate of 0,7.5, 15 or 25 mg a.i./m2 to well established kentucky bluegrass under wellwatered(100 of field capacity) or drought-stressed (70 and 40% of fieldcapacity) conditions. the effect of pro-ca on the growth physiology, droughtstress response, antioxidant activity, and lipid peroxidation of kentuckybluegrass exposed to drought stress was measured during 28 days at 7 daysinterval. pro-ca treated kentucky bluegrass exposed to drought stress hadhigher relative water content (rwc) and turf quality, and lower electrolyteleakage and malondialdehyde (mda) content as membrane integrity indicators,compared with untreated plants. pro-ca application significantly increasedthe antioxidant enzymes superoxide dismutase (sod), ascorbate peroxidase(apx) and catalase (cat) activities under well-watered and droughtconditions, but this increase is more evident in drought stressed plants. pro-ca application at 15 mg/m2 was found to be more effective in alleviatingdrought stress damage in kentucky bluegrass. the results from this studysuggest that pro-ca enhanced drought stress tolerance in kentucky bluegrassby maintaining higher rwc and membrane stability.