PHYSIOLOGICAL TRAITS AND GENETIC VARIATIONS ASSOCIATED WITH DROUGHT AND HEAT TOLERANCE IN CREEPING BENTGRASS

摘要

Drought and heat stress are two abiotic stresses limiting turfgrass.The objectives of this study were examine cultivar variations in drought and heat tolerance and determine major physiological traits associated with the genotypic variation in drought and heat tolerance in creeping bentgrass (Agrostis stolonifera L.).Plants of eight cultivars,‘Declaration’,‘Kingpin’,‘L93’,‘Penncross’,‘Pro-as7’,‘Shark’,‘Tyee’,and ‘007’,were subjected to drought stress by withholding irrigation,heat stress by exposing plants to 35/30 oC (dayight temperature),or non-stress conditions with adequate water and normal temperature (20/15 oC) in growth chambers.Comparative analysis of cultivar variations in drought and heat responses using physiological traits (leaf chlorophyll content,photochemical efficiency,electrolyte leakage,relative water content,and membrane lipid peroxidation) indicated that among eight cultivars,‘007’,‘Declaration’ and ‘Pro-as7’ were the most drought tolerant,‘Kingpin’,‘L93’,‘Penncross’ and ‘Tyee’ were of intermediate tolerance,while ‘Shark’ was the most drought sensitive; for heat tolerance,’Declaration’,‘L93’,and ‘007’ were the most tolerant,‘Pro-as7’ and ‘Shark’ had an intermediate level of tolerance and ‘Kingpin’ and ‘Penncross’ were the most sensitive.Correlation and backward elimination regression analysis among physiological traits and turf quality indicated that compared to other parameters,electrolyte leakage and relative water content were better indicators for cultivar variations in drought tolerance while chlorophyll content and photochemical efficiency were better indicators for heat tolerance.These major physiological traits could be used for the selection of drought and heat-tolerant germplasm for creeping bentgrass and other cool-season turfgrass species.