Effect of polyamine precursors and antioxidants on growth and metabolism of salt-stressed barley

Abstract

Background Salt stress, a significant environmental problem was studied in barley cultivars Giza 124 and Giza 119 at various stages (seedling, pre-flowering, and yield). This study aimed to investigate the impact of salt stress on these cultivars, examine the effects of polyamine precursors (arginine, methionine, and ornithine) on their response to salt stress, and assess the efficacy of antioxidants (glutathione and ascorbic acid) in alleviating the harmful effects of salt stress on barley plants. Methods Barley grains were germinated and subjected to salinity stress, with subsequent treatment using glutathione, ascorbic acid, or an amino acid mixture. Growth criteria, photosynthetic pigments, metabolites, antioxidant enzymes, mineral content, and polyamines were analyzed. Results The impact of 100Mm NaCl, with or without glutathione, ascorbic acid, or amino acid mixtures, on various physiological parameters in G124 and G119 were investigated. The levels of chlorophyll a, chlorophyll b, and carotenoids significantly varied under different treatments. For instance, chlorophyll a in G 124 exhibited a 23% reduction under salt stress compared to the control, while the addition of glutathione mitigated this effect, resulting in a 17% increase compared to the NaCl treatment. Similar trends were observed for chlorophyll b and carotenoids. At the yield stage, both cultivars demonstrated a significant decrease in the the weight of grains per plant under salinity, which was alleviated by the addition of ascorbic acid, glutathione, or amino acid mixtures. Conclusion The application of glutathione, ascorbic acid, or an amino acid mixture mitigated the adverse effects of salt stress on various parameters. The results highlight the potentail of these compounds in enhancing plant tolerance to salinity stress and offer insights into the physiological response of barley cultivars under adverse conditions.