Morpho-physiological and biochemical responses of finger millet (Eleusine coracana (L.) Gaertn.) genotypes to PEG-induced osmotic stress

The effect of PEG-induced (0-25%) osmotic stress was studied in twelve diverse indigenous finger millet genotypes under various levels. With the increasing PEG concentration germination percentage, shoot length, root length, and biomass production decreased in all the genotypes. Among all the genotypes evaluated, reduction in germination percentage, seedling growth, and biomass production was more in FM/RT/01 and less in FM/ST/01. Principal component analysis (PCA) resulted in the formation of three distinct clusters, stress-sensitive (FM/RT/01, FM/RT/03, FM/SD/01, and FM/ST/02), stress-tolerant (FM/ST/01, FM/ST/03, and FM/KP/02) and moderately tolerant/sensitive (FM/KP/01, FM/RT/02, FM/RT/04, FM/RT/05, and FM/RG/01). Based on the germination percentage and growth parameters, FM/RT/01 was considered as PEG-induced osmotic stress-sensitive, and FM/ST/01 as stress-tolerant genotype. PEG-induced stress increases membrane damage (MDA content) and osmolyte accumulation (free proline, glycine betaine, and total soluble sugars) in both the genotypes. Damage to the membrane was found more in the stress-sensitive genotype (FM/RT/01) compared to stress-tolerant (FM/ST/01). The magnitude of increase in osmolyte accumulation was more in FM/ST/01 than FM/RT/01. Antioxidative enzyme activities (SOD, CAT, APX, and GPX) significantly increased with increasing PEG 6000 concentration up to 15% PEG but decreased at higher concentrations (20 and 25%) in both the genotypes. Our findings suggests, genotype FM/ST/01 genotype can be exploited for different crop improvement programs.