Morpho-physiological and biochemical variations in finger millet genotypes under induced salinity stress at seedling stage

Soil salinity is one of the most devastating environmental impediments that poses a significant threat to agricultural practices hamper crop productivity worldwide. In the present study, a total of thirty finger millet genotypes were examined through in vitro screening at varying sodium chloride concentrations (0, 75, 175, 275, and 375 mM). Based on the morphological characteristics, visual salt injury (VSI) and salinity susceptibility index (SSI), two tolerant (TRY-1 and ML-365), two moderately tolerant (GPU-48 and GPU-28) and two susceptible (VL-146 and Indaf-9) genotypes were shortlisted. Further, the greenhouse illustrated the experiment to assess physiological and biochemical response at the seedling stage by imposing sodium chloride concentrations (0 and 375 mM). The results revealed that TRY-1 was on par among all the studied genotypes that exhibited a significant increase (P < 0.05) in phenotypic (germination percentage, shoot length, root length, and seedling vigour index) biochemical characteristics (contents of total chlorophyll, proline, phenolic, and flavonoids) and antioxidant enzyme activities (SOD and CAT) under varying salinity regimes indicating a strong defense mechanism against salinity-induced oxidative and osmotic stress. In contrast, Indaf-9 exhibited a significant decrease in all the growth and physiological traits and an increment in MDA and H2O2 content compared to other genotypes. In Indaf-9, MDA increased by 184% whereas in TRY-1, it increased by 105%. In contrast, proline content was enhanced as maximum in TRY -1 (239%) compared to Indaf-9 (191%) from 0 to 375 mM sodium chloride concentration. Our findings were supported by extensive statistical analyses such as cluster analysis, correlation, and PCA, indicating key contributing traits involved in salinity stress tolerance. Therefore, this study may help select the salt-tolerant genotypes and contribute to sustainable agriculture by increasing food production in saline-prone agroecological zones.