Investigative approaches associated with plausible chemical and biochemical markers for screening wheat genotypes under salinity stress

Twenty genotypes of wheat resulting from different crossings between some wheat parental lines were compared for salt stress (control and gradually increasing salinity). Ion content in root, shoot, and flag leaves and also the root and shoot dry weights were measured. Based on these results, eight genotypes among the twenty were selected as susceptible, semi-tolerant, and tolerant genotypes for evaluating their biochemical characteristics. Results indicated that concentration of sodium (Na+) and potassium (K+) in shoot, root, and flag leaves of stressed plants were, respectively, higher and lower than that in the non-stressed plants. Overall, salinity stress caused reductions in root and shoot dry weights and relative water content (RWC), but enhancement in pigments content. Concentrations of the total carbohydrate, total protein, and soluble proline were higher in plants under salt stress condition. Salinity stress induced higher production in hydrogen peroxide (H2O2) and malondialdehyde (MDA) and also higher activity of catalase (CAT) and ascorbic peroxidase (APX) as antioxidant enzymes, but lower activity of peroxidase (POD). Genotypes 4s, Arg, and 386dh had generally higher enzymatic activity and other tolerant indices, and hence they can be introduced as tolerant genotypes for more study by the plant breeders. On the other hand, genotype 278s was most susceptible based on the most results.