Effects of Water Stress on Growth, Forage Yield and Genetic Variation of Three Phenological Groups of Tall Fescue (Festuca arundinacea) in Isfahan Region

The ability of phenological adjustment and accelerate maturation is one of the most drought tolerance mechanisms in crops. Tall fescue is one of the valuable forage and turf grasses that is used to prevent soil erosion and produce forage in pastures and is compatible with most soils and climates. In this research, yield potential and genetic variation of three phenological groups including mid-flowering group (parental group), early and late flowering groups each containing 25 genotypes, selected from a poly cross community, were studied under non-stress and water deficit conditions in the research farm of Isfahan University of Technology for two years. Irrigation was applied when 90 and 50% of available soil water were depleted for stress and normal environments, respectively. The results showed that there was considerable variation in the studied germplasms in terms of all studied traits and responses to water deficit stress. The highest value of genetic variation belonged to forage yield. The results showed that dry forage yield in the first and second harvest stress decreased by 17% and 52% due to water deficit, respectively. The highest estimate of heritability was related to the trait of day to anthesis and the lowest was related to the percentage of dry matter and forage yield. The results showed that the highest dry forage yield under non-stress conditions belonged to the late flowering group. Means comparison of genotypes showed that the highest dry forage yield under normal and water stress belonged to genotypes 10 (from America with 209.50 g/plant) and 3 (from Yasouj with 142.25 g/plant), respectively, in the late flowering group, genotypes 25 (from Shahrood with 383 g/plant) and 22 (from Poland with 178.50 g/plant), respectively in early flowering group and genotypes 25 (from Shahrood) with 222.50 and 182.25 g/plant in the parental group, respectively. The results indicate that the studied genotypes may have incomplete summer dormancy that should be investigated in future studies. Considerable genetic diversity between and within phenological groups and their different responses to drought stress can be used to develop and produce suitable synthetic varieties for soils with limited water resources.