Effect of PEG induced water stress on chlorophyll content, membrane injury index, osmoprotectants and antioxidant enzymes activities in sorghum (Sorghum bicolor (L) Moench)

In the present study, six drought susceptible, six drought tolerant and seven wild sorghum genotypes were compared for their response to varying degrees of PEG-6000 induced water stress. Germination percentages, root length, shoot length, root to shoot ratio and chlorophyll content were decreased however membrane injury index was increased with increasing water stress. Under stress drought tolerant genotypes had more chlorophyll a, chlorophyll b, total chlorophyll content and less membrane injury index. A drought tolerant genotype M-35-1 had maximum root length, shoot length, and less membrane injury index than the rest of the genotypes. Proline content and activity of P5CS increased in all genotypes of sorghum due to water stress. Wild genotypes had higher proline content under water stress however; fold increase of proline was higher in drought tolerant genotypes. Soluble protein also increased in all sorghum genotypes in response to imposed water stress. Activities of antioxidant enzymes viz., SOD, POD, CAT increased under stressed condition in all sorghum genotypes. Activities of all these enzymes were higher in drought tolerant genotypes followed by those wild genotypes. Highest antioxidant enzyme activities under moisture stress condition were found in M-35-1, a drought tolerant genotype which may contribute for its better adaptation under water stress.