Work

Optimizing foliar nutrient timing: Soluble monoammonium phosphate applications improve maize physiological parameters and productivity under water stress

Year: 2025

Type: article

Abstract: In Brazil, most ( Zea mays L.) production is in the off‐season, following the summer soybean [ Glycine max (L.) Merrill] harvest, a period often affected by water scarcity during critical growth stages, which can substantially reduce yields. To address this challenge, foliar nutrient applications can mitigate drought damage if timed correctly. Thus, this study aimed to evaluate the effect of monoammonium phosphate (MAP: 12‐61‐00) via foliar application at various development stages on maize plant physiology and productivity under water‐limited conditions. The research employed a randomized block design with eight treatments and four replicates: a control; MAP applications at V 4 , V 6 , V 8 , R 1 , and MAP applied at all stages (MAP‐All) (all four stages: V 4 + V 6 + V 8 + R 1 ); and two additional treatments supplying nitrogen (N) via urea equivalent to that from MAP: N‐V 6 and nitrogen applied at all stages (N‐All) (V 4 + V 6 + V 8 + R 1 ). Assessments included leaf nutrient content, photosynthetic pigment content, gas exchange parameters, ribulose‐1,5‐bisphosphate carboxylase/oxygenase (Rubisco) activity, lipid peroxidation, antioxidant enzyme activity, carbohydrate content, and grain yield (GY). The MAP‐All treatment demonstrated the most significant positive effects, enhancing the contents of chlorophyll a and b, total chlorophyll, and carotenoids and improving net photosynthesis, stomatal conductance, carboxylation efficiency, and Rubisco activity. This increase in photosynthetic efficiency led to reduced lipid peroxidation and the necessary actions of antioxidant enzymes, leading to greater sugar production in leaves. This resulted in an average increase in GY of 16% compared to the control, equivalent to 884 kg ha −1 . The N‐All treatment, despite providing a lower dose of N, increased GY by 10% compared to the control, or 408.6 kg ha −1 . These findings indicate that foliar MAP applications effectively enhance maize physiological conditions by supplying phosphorus and nitrogen to boost photosynthetic and productive metabolism in off‐season maize.

Source: Agronomy Journal

DOI: 10.1002/agj2.70234