Foliar selenium influence on agronomic performance, grain quality and water use efficiency of common bean (Phaseolus Vulgaris l.) under water stress conditions

Abstract

Water scarcity is a critical global issue, especially in arid and semi-arid regions where agricultural productivity heavily depends on irrigation. Common beans (Phaseolus vulgaris L.), a vital legume for food and nutrition security, is highly sensitive to water deficits. This study was conducted to evaluate the effects of foliar selenium (Se) application on the growth, yield and Water Use Efficiency (WUE) of common beans under Deficit Irrigation (DI). The experiment was carried out in a greenhouse at Egerton University using Surface Drip Irrigation (SDI). Treatments involved three irrigation levels (100%, 70% and 50% of crop evapotranspiration (ETc) combined with four selenium concentrations (0, 0.5, 1.0 and 1.5 mg/L), arranged in a factorial design with three replications. Selenium applications were done 23 days after sowing and during vegetative, flowering, pod formation stages. The growth parameters (plant height, leaf number, branches and leaf area index), yield components (pod length, pods per plant, seed number and yield), were monitored across various growth stages and after harvesting. The results demonstrated full irrigation 100% ETc with 1.5 mg/L Se application resulted in highest vegetative growth parameters and yield parameters while moderate water stress (70% ETc) combined with 1.5 mg/L Se application significantly enhanced growth and yield of common beans and improved WUE. The highest selenium accumulation in the grains (0.445 mg/Kg) was observed at 50% ETc together with application of 1.5 mg/L Se concentration, exceeding the daily consumption allowable limit. This implied that plants under water stress absorbed and retained more selenium compared to those under full irrigation. For optimal yield and WUE, the study indicated 70% ETc irrigation level combined with 1.5 mg/L of foliar selenium concentration with the optimum yield (10348.1 Kg/Ha) while maintaining a high WUE (0.357 Kg/m³) as compared to the control (100 ETc with no selenium). This confirms the potential of integrating deficit irrigation with foliar Se application to optimize water use while improving bean productivity and nutritional quality. Notably, foliar Se enhanced the plants’ physiological tolerance to water stress, particularly during flowering and pod formation. Therefore, Se application can help improve drought resilience, enhances physiological performance and supports sustainable agricultural limited water availability, contributing to SDG 2 (End hunger, achieve food security and improved sustainable agriculture), as well as ensuring safe food production under SDG 3.