Presowing seed treatment with glycine betaine confers NaCl tolerance in quinoa by modulating some physiological processes and antioxidant machinery

Abstract

Soil salinity threatens the yield and food security worldwide and use of halophytes might be a valid option to cope with devastating salinity effects. The present investigation was accomplished to evaluate the role of glycine betaine (GB) as presowing seed treatment on growth parameters, photosynthetic pigments, gas exchange attributes, enzymatic antioxidants, lipid peroxidation (MDA), hydrogen peroxide (H2 O2 ), endogenous GB, total soluble proteins (TSP), and yield in quinoa (Chenopodium quinoa) under saline conditions. Ames-13737 (Q7) and PI-634919 (Q9) quinoa accessions were used for this trial. The plants were applied with two salt stress treatments (Control and 450 mM NaCl) after 45 days of sowing. Presowing seed treatments with GB (water, 10 and 20 mM) were given for 12 h. Each treatment replicated four times through completely randomized design. Imposition of salinity triggered a major decrease in growth, photosynthetic pigments, net CO2 assimilation rate (A), transpiration rate (E), and stomatal conductance (gs ), while the level of lipid peroxidation and activities of superoxide dismutase (SOD) and catalase (CAT) were enhanced. Slight increment in total soluble proteins was observed along with higher endogenous GB in quinoa under salinity. Both levels of GB increased the shoot length, shoot fresh, and dry weights in accession PI-634919 under saline regime. Photosynthetic attributes, E and gs were increased when 20 mM of GB was applied under saline conditions. Activities of antioxidant enzymes, TSP, endogenous glycine betaine and yield parameters were also increased when GB was applied. Presowing treatment with GB in quinoa plants prominently decreased the MDA and H2 O2 concentration. The concentration of 10 mM GB enhanced the panicle length while 20 mM GB showed same results for 1000 seed weight and TSP under saline conditions. Overall, quinoa accession Ames-13737 was better as compared to PI-634919 in terms of growth rate, photosynthetic properties, gas exchange parameters, enzymatic antioxidants, and yield.