Insight into in-vitro biochemical amelioration by bio-stimulants under salt stress in pea (Pisum sativum L.) and impact on growth, yield and quality in-situ

Pea, which is the most important legume globally, is valued for its profitability and short growth cycle. However, increasing soil salinity threatens pea and other crops by reducing productivity. Bio-stimulants, such as Rhizobium sp. and seaweed extract, are compounds or microbes that are given to plants or the rhizosphere to increase nutrient efficiency, nutrient uptake, crop quality, and abiotic stress tolerance. But their combined efficacy for growth, yield, quality and mitigating salt stress in pea remains underexplored. This research, was conducted to explore the combined efficiency of Rhizobium inoculation and seaweed extract application in natural field conditions as well as in in-vitro conditions. The experiment was conducted in rabi season of year 2023–24. For lab conditions under salt stress, five treatments of bio-stimulants were applied: Control, NaCl (100 mM), NaCl + Rhizobium leguminosarum (RZ), NaCl + seaweed extract, Ascophyllum nodosum (SWE), and NaCl + RZ + SWE. However, for field trails under natural conditions treatments namely; Control, NPK (RDF), RDF+ RZ, RDF + SWE, and RDF + RZ + SWE were used. Salt stress significantly decreases physiological and germination parameters, protein content, and photosynthetic pigments, while increasing proline, malondialdehyde, hydrogen peroxide, superoxide anion levels, and antioxidant enzyme activities, leading to membrane damage, osmotic stress, ion toxicity (Na + and Cl − ), and oxidative damage, impairing water uptake and nutrient balance in lab condition. The combined application of Rhizobium leguminosarum and seaweed extract mitigated salt-induced phytotoxicity, enhanced germination and biochemical parameters. In field conditions, combined bio-stimulant treatments improved growth, yield, and quality attributes of both varieties, with Punjab-89 outperforming Arkel in both controlled and field settings. These findings underscore the potential of combined application of bio-stimulants in alleviating salt-induced oxidative stress and enhanced pea productivity, providing a long-term approach to enhancing crop growth soil health and resistance to abiotic stresses.