Effect of water deficit stress on some physiological and biochemical traits of forage sorghum genotypes

This study was performed to investigate the effect of water deficit stress on the some activities antioxidant enzymes, photosynthetic pigments and forage yield of sorghum genotypes. This experiment was conducted to factorial based on completely randomized design with three replications in greenhouse of University of Mohaghegh Ardabili in 2013. Treatments consisted of irrigation at four levels (85, 65, 45 and 25% of field capacity) and three genotypes of forage sorghum (KFS2, KFS6, and KFS17). Catalase, peroxidase and polyphenol oxidase enzymes and soluble sugar content, proline and carotenoids, increased in severe stress (25% field capacity) and decreased chlorophyll a and chlorophyll b. KFS6 genotype had the highest chlorophyll a, chlorophyll b, and total chlorophyll, however, the maximum biomass, proline, soluble sugars, peroxidase and polyphenol oxidase activity and carotenoid were observed by KFS2 genotype. Also positive correlation were observed between the biomass production and carotenoid and chlorophyll content, proline, soluble sugar, catalase, peroxidase and negative correlation between biomass and polyphenol oxidase. Between photosynthetic indices, chlorophyll a, between adjustment indices, peroxidase activity had maximum contribution to prediction biomass. Also in KFS2 genotype except carotenoid and proline all traits had highest correlation with biomass. In general KFS2 genotypes introduced tolerant to water stress as compared with the other genotypes.