Foliar magnesium application: A new nutrient management strategy to enhance peanut yield in phosphorus-limited soils

Sustainable peanut production, a critical source of edible oil and plant protein, is often constrained by phosphorus (P) deficiency in soils. Developing practical agronomic strategies to enhance crop resilience under such nutrient stress is vital for securing food production. This study aimed to evaluate the efficacy and physiological basis of foliar magnesium (Mg) application as a potential nutrient management strategy to improve peanut performance in P-limited environments. A two-year field study evaluated the effects of exogenous magnesium on growth and photosynthetic performance in two peanut varieties with contrasting photosynthetic P-use efficiency (PPUE) under limiting and adequate P availability conditions. The high-PPUE variety (ICG4750, "H") and lowPPUE variety (ICG9249, "L") were treated with either foliar-applied magnesium (M1) or no magnesium (M0). Physiological, biochemical, and agronomic parameters were measured. The results confirmed that phosphorus deficiency severely inhibited plant growth and final pod yield. Foliar Mg application effectively mitigated these adverse effects, restoring biomass and yield. Physiologically, Mg supplementation enhanced stomatal conductance and protected the photosynthetic apparatus from photoinhibition, which was associated with improved electron transport and increased ATP synthase activity. Moreover, the high-PPUE genotype (H) showed stronger growth and photosynthetic performance than the low-PPUE genotype (L), highlighting the role of genetic background in the effectiveness of nutrient management. These findings demonstrate that foliar Mg application is a viable agronomic practice to enhance peanut productivity in P-deficient soils. The interaction between Mg nutrition and varietal P efficiency offers a promising approach for integrated nutrient management, contributing to more sustainable peanut cultivation systems.