Exogenous 24-Epibrassinolide Elevates the Salt Tolerance Potential of Pea (Pisum sativum L.) by Improving Osmotic Adjustment Capacity and Leaf Water Relations

Abstract

Salinity, as a wide spread problem around the globe, can drastically limits the crop growth and productivity. Therefore, there is a growing need to mitigate the drastic effects of this abiotic stress through the use some sustaiable short-term or long term approaches. An investigation was carried out to assess the potential role of 24-epibrassinolide (EBL) in mitigating the drastic effects of salt stress on growth, water relations, osmolytes, and ions accumulation of salt-tolerant and salt-sensitive pea genotypes. EBL treatment significantly altered the leaf water status and accumulation of osmolytes and various ions in salt-stressed [with sodium chloride (+NaCl)] plants. The plants of both salt-tolerant and salt-sensitive genotypes, subjected to +NaCl conditions had a significant reduction in plant fresh and dry weights, internodal distance, leaf area (LA), leaf water potential (w), leaf osmotic potential (o), leaf turgor potential (t), relative water content (RWC), number of seeds pod−1, seed weight, root/leaf inorganic osmolytes (Ca2+, K+ and Mg2+), while increased the levels of root/leaf proline, glycinebetaine, total free amino acids, total soluble sugars, sodium (Na+), and chloride (Cl−). There was non-significant effect of EBL on number of pods plant−1 both under saline and non-saline conditions. However, the foliar application of EBL significantly alleviated the deleterious effects of salinity by improving the plant biomass, water relations and concentration of organic/inorganic osmolytes and yield attributes. However, EBL minimized the drastic effects of salt stress by limiting the root/leaf Na+ and Cl− contents. It can be concluded that EBL efficiently alleviated the salinity-induced drastic effects by improving the water status of plant tissues, which led to salt dilution within plant tissues, thus minimized the ion-toxicity, ultimately elevated the plant growth by minimizing the toxic action of Na+ and Cl−. Secondly, EBL augmented the salt-tolerance capacity of tested pea genotypes by enhancing their osmotic adjustment potential, in terms of high accumulation of organic and inorganic osmolytes within leaf and root tissues.