Vicia faba L. Symbiotic Nitrogen Fixation and Water Productivity to Foliar Proline Application under Salinity Stress

Abstract

Salinity stress is a major constraint limiting legume productivity and biological nitrogen fixation in arid and semi-arid agroecosystems. This study evaluates the response of Vicia faba L. to foliar application of proline under saline conditions, with particular emphasis on symbiotic nitrogen fixation and water productivity. A field experiment was conducted using graded salinity levels combined with foliar proline treatments to assess plant physiological performance, nodulation characteristics, and yield-related attributes. The results demonstrated that salinity stress significantly reduced nodule formation, nitrogen fixation efficiency, and overall plant growth, leading to lower biomass and yield. However, foliar application of proline mitigated the adverse effects of salinity by enhancing osmotic adjustment, stabilizing cellular structures, and improving enzymatic activity associated with nitrogen metabolism. Treated plants exhibited increased nodule number and activity, resulting in improved nitrogen assimilation and higher productivity. Additionally, proline application enhanced water-use efficiency by maintaining better plant water status and reducing stress-induced damage. The interaction between proline treatment and salinity levels indicated that moderate application rates were most effective in improving physiological resilience and crop performance. While analytical methods were employed to evaluate biochemical and physiological responses, the primary focus remained on crop adaptation and agronomic improvement under stress conditions. The findings highlight the potential of foliar proline application as a practical strategy to enhance nitrogen fixation, improve water productivity, and sustain yield in Vicia faba under saline environments. This research contributes to sustainable agriculture by supporting stress-resilient crop management practices.