Enhancement of drought tolerance in maize through novel exogenous plant growth regulators and native microbiome consortia under variable water stress.

Project Abstract

The study investigates the enhancement of drought tolerance in maize by employing novel exogenous plant growth regulators (PGRs) in combination with native microbiome consortia under variable water stress conditions, aiming to develop an integrated, sustainable strategy for maintaining yield stability in water-limited environments. Field and controlled-environment experiments were conducted across two growing seasons with three water regimes representing well-watered, moderate deficit, and severe deficit stress, to simulate realistic agronomic scenarios. A factorial arrangement tested multiple concentrations of selected exogenous PGRs (including focal plant hormones and synthetic analogs) and consortia derived from locally adapted maize rhizosphere microbiota, enabling the assessment of synergistic and antagonistic interactions on root architecture, stomatal conductance, chlorophyll fluorescence, osmolyte accumulation, and antioxidant enzyme activities. Physiological measurements indicated that treated plants under drought stress exhibited improved water-use efficiency, greater leaf water potential maintenance, and delayed onset of terminal senescence compared with untreated controls. Biochemical analyses revealed elevated proline and soluble sugar contents, stabilization of photosystem II, and enhanced activity of catalase, superoxide dismutase, and ascorbate peroxidase, suggesting a fortified reactive oxygen species scavenging system. Root phenotyping showed increased root length density and deeper rooting in PGR-microbiome-treated plants, likely facilitating better water extraction from deeper layers. At the molecular level, transcriptomic profiling highlighted upregulation of drought-responsive pathways, abscisic acid signaling components, and genes associated with osmotic adjustment, membrane stability, and phytohormone crosstalk, with particular enrichment in the cross-regulation of auxin, cytokinin, and ethylene pathways. Yield-related parameters demonstrated that the combination treatment mitigated grain-filling impairment under deficit irrigation, resulting in grain number, kernel weight, and total grain yield improvements ranging from 12% to 28% relative to controls under moderate stress, and 6% to 15% under severe stress, depending on the PGR and microbial consortium used. Microbiome sequencing revealed a shift toward drought-tolerant, plant-beneficial taxa, with enriched functions related to ACC deaminase activity, siderophore production, and osmotolerance traits, suggesting enhanced root-microbe synergy. Economic analysis indicated a favorable cost-to-benefit ratio when PGRs were applied at optimized, low-cost dosages and in combination with locally adapted microbial consortia, highlighting potential for scalable adoption by smallholder farmers. The study advances understanding of how exogenous PGRs can prime plant hormonal networks to harness microbial assistance for drought resilience, and provides a practical framework for deploying microbe-assisted PGR treatments as a climate-smart agronomic strategy. Limitations include genotype-specific responses, environmental interaction effects, and the need for long-term multi-location trials to validate stability and consistency of results. Future work will explore dose optimization, formulation stability, and integration with precision irrigation scheduling to maximize resource use efficiency.

Project Overview

What This Project Is About

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The project looks at how adding certain plant growth regulators from outside the plant and combining them with friendly soil microbes can help maize cope with drought. It tests whether these tools can improve growth, yield, and water use efficiency when water becomes limited.

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The Problem It Addresses

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Maize yields drop sharply during dry spells, and farmers often lack affordable ways to protect crops. Traditional watering is expensive and unsustainable. The study explores a low-input approach that uses natural helpers (microbes) and gentle chemical signals (growth regulators) to boost drought resilience.

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Objectives of the Project

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1. Identify effective exogenous plant growth regulators for maize under drought.
2. Find native soil microbes that are compatible with the regulators to support plant health.
3. Evaluate effects on plant growth, root development, and water use efficiency.
4. Assess changes in yield and grain quality under water stress conditions.
5. Provide practical guidelines for field use and safety considerations.

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What You Will Do Step by Step

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1) Review simple literature to choose safe regulators and microbes. 2) Set up small trials with different regulator–microbe combos under simulated drought. 3) Measure plant height, biomass, root growth, and leaf water status. 4) Record yield-related data at harvest. 5) Analyze the data to see which combo works best and why. 6) Summarize findings and recommend practical steps for farmers.

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Expected Outcome

We expect some regulator–microbe combinations to improve maize growth and water efficiency under drought, leading to higher yields and more stable performance. The study should produce simple guidelines for farmers and researchers to apply the approach in real fields.