The foliar application of amino acid enriched fertilizer improves drought tolerance in common bean (Phaseolus vulgaris L.)

Abstract

With the increasing threat of climate change and water scarcity, there is a pressing need to enhance crop productivity and water-use efficiency. Common bean (Phaseolus vulgaris L.) is a vital food source due to its nutritional value, which makes it important to improve its resilience to water deficits. This study investigated the effects of foliar application of an organic fertilizer as a nitrogen (N) source on mitigating the negative consequences of water deficit stress and enhancing grain yield in common bean. We hypothesized that foliar application of mineral fertilizer as an N source to common bean could enhance tolerance to water deficits and improve grain yields in crops by improving N metabolism in these plants. The experiment employed a greenhouse setup with two factors: water availability (well-watered and water-withholding) and foliar fertilization (with and without). The common bean variety BRSMG MARTE was subjected to foliar application of mineral fertilizer (Vislumbre®; AgroPrime, Brazil) at the V4 stage. Under water deficit conditions, mineral fertilizer-treated plants exhibited reduced stomatal conductance and transpiration, indicating improved water-use efficiency. Additionally, they maintained a higher relative water content and intrinsic water use efficiency than non-treated plants. However, plants irrigated without mineral fertilizers displayed increased photosynthesis. Mineral fertilizer application led to elevated leaf concentrations of amino acids and proline under maximum stress conditions, and enhanced starch accumulation during rehydration. Although protein accumulation was reduced in mineral fertilizer-treated plants under water deficit conditions, they demonstrated increased ammonium uptake. The activity of ascorbate peroxidase was enhanced under maximum stress conditions, whereas superoxide dismutase activity was higher in irrigated plants with mineral fertilizer and untreated water-deficit plants. Catalase activity was elevated in untreated, water-deficient plants under maximum stress conditions. Notably, mineral fertilizer-treated plants under water-deficit conditions exhibited increased grain numbers, indicating improved drought tolerance. However, they displayed lower seed weights and fewer pods than irrigated plants without organic fertilizer treatment. These findings highlight the potential of foliar application of mineral fertilizer to enhance water deficit tolerance and grain yield in common bean.