Impact of foliar micronutrient application on wheat grain protein and yield under drought stress conditions

Project Abstract

Under drought stress, wheat grains exhibit reduced protein concentration and yield, driven by impaired photosynthesis, disrupted nutrient transport, and oxidative stress; this study investigates the efficacy of foliar micronutrient spraying as a management strategy to mitigate these effects and enhance grain quality and productivity. A multi-location field experiment was conducted over two growing seasons in representative wheat-growing agro-ecologies, employing a split-plot design with water regime (irrigated vs. drought-stressed) as the main plot and foliar micronutrient treatments as subplots. Treatments included a control (no foliar spray), single micronutrient sprays (Zn, Fe, Mn, Cu, and B), and a composite spray combining all five micronutrients, applied at key phenological stages (tillering, heading, and grain filling) at label-recommended concentrations. Physiological measurements encompassed chlorophyll content, leaf relative water content, stomatal conductance, and photosynthetic rate; biochemical analyses encompassed leaf and grain micronutrient concentrations, antioxidant enzyme activities (superoxide dismutase, catalase, peroxidase), lipid peroxidation (malondialdehyde), and soluble sugar content. End-use quality was assessed via grain protein, gluten strength, and test weight, while yield components included thousand-kernel weight, grain number per spike, and total grain yield. Results indicate that drought stress significantly reduced grain yield and protein concentration, with declines correlating to decreased photosynthetic efficiency and elevated oxidative damage. Foliar application of a composite micronutrient spray consistently outperformed individual nutrients, restoring chlorophyll content and photosynthesis, maintaining higher stomatal conductance, and reducing lipid peroxidation under drought. Grain micronutrient status improved notably for Zn and Fe, which correlated with enhanced amino acid synthesis and protein accumulation; Mn and Cu contributed to improved cell wall integrity and enzymatic activity, while boron facilitated improved carbohydrate transport to developing grains. Consequently, foliar micronutrient treatment under drought increased grain yield by up to 18% and grain protein concentration by 6–9% across locations, with the most pronounced gains observed in water-stressed plots receiving the composite spray at tillering and grain-filling stages. Antioxidant enzyme activities were elevated in treated plants, indicating strengthened defense against drought-induced oxidative stress; this biochemical resilience translated into better grain filling and higher test weights. The economic analysis revealed favorable cost-to-benefit ratios for the composite foliar micronutrient regimen, particularly in mid-to-high rainfall environments where drought pressure coincides with critical grain-filling periods. The study demonstrates that strategic foliar micronutrient applications can mitigate drought-induced yield losses and improve grain quality by reinforcing photosynthetic capacity, nutrient partitioning, and antioxidant defenses, offering a practical agronomic option for sustaining wheat productivity under water-limited conditions. Recommendations include optimizing spray timing to coincide with key developmental stages, calibrating micronutrient concentrations to target specific soil–plant nutrient dynamics, and integrating foliar micronutrients with broader drought-adaptation practices for robust, field-level resilience.

Project Overview

What This Project Is About

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A plain-language overview of the topic and what the project investigates.

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The Problem It Addresses

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What problem or gap this project tackles and why it matters to the field or society.

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Objectives of the Project

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1. Assess how foliar micronutrients affect wheat grain protein under drought.
2. Measure changes in grain yield with micronutrient foliar sprays.
3. Identify which micronutrients provide the strongest benefits under water stress.
4. Explore potential interactions between drought level, nutrient type, and plant stage.

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What You Will Do Step by Step

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1. Review background literature on micronutrients and drought tolerance in wheat.
2. Design a small field or greenhouse trial with controlled water stress and foliar sprays.
3. Apply selected micronutrient treatments at specific growth stages.
4. Collect data on grain yield, grain protein, and plant health indicators.
5. Analyze results to compare treated vs. untreated plants and determine significance.
6. Discuss practical implications for growers and future research ideas.

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Expected Outcome

Expected to identify foliar micronutrient treatments that improve grain protein and yield under drought, offering practical guidance for farmers and contributing to more resilient wheat production.