Impact of drought-tolerant crop varieties on yield stability and water-use efficiency under varying irrigation regimes in rain-fed agro-ecosystems

Project Abstract

Drought-induced stress poses a major threat to rain-fed agro-ecosystems, compromising yield stability and water-use efficiency (WUE) across staple crops. This study evaluates the performance of drought-tolerant crop varieties under a gradient of irrigation regimes to elucidate mechanisms driving yield resilience and WUE in environments with limited and variable rainfall. The research was conducted across two agro-ecological zones with contrasting rainfall patterns, employing a split-plot design over two growing seasons. Main plots comprised irrigation regimes representing full irrigation, deficit irrigation at 70%, and regulated deficit irrigation at 50% of crop evapotranspiration, while sub-plots included conventional cultivars and modern drought-tolerant varieties of maize, sorghum, and chickpea. Physiological, phenological, and yield-related traits were measured, including stomatal conductance, leaf water potential, relative water content, photosynthetic rate, chlorophyll fluorescence, root depth distribution, flowering time, grain filling duration, and harvest index. Soil moisture profiles, plant-available water, and rainfall interception were continuously monitored, enabling precise WUE calculations as grain or seed yield per unit water transpired. In addition, physiological traits associated with osmotic adjustment, antioxidant activity, and abscisic acid signaling were quantified to uncover biochemical pathways conferring drought tolerance. Data were analyzed using mixed-effects models to separate genotype-by-environment interactions from irrigation effects, with stability analyzed via multiple-drought-tolerance indices and reliability analysis across sites and years. The results indicate that drought-tolerant varieties consistently outperformed traditional cultivars under moderate to severe water deficits, maintaining yield stability through optimized stomatal regulation, deeper root systems, and sustained photosynthetic efficiency. Notably, WUE gains were achieved without substantial yield penalties under deficit regimes, attributed to improved source-sink balance and enhanced osmotic adjustment that preserved leaf turgor during grain fill. Genotype-by-environment interactions revealed that the magnitude of yield advantage under limited irrigation was highly climate-dependent, with certain drought-tolerant lines delivering robust performance in both zones. The study also demonstrates that regulated deficit irrigation can synergize with drought-tolerant genotypes to maximize WUE and economic yield by aligning irrigation timing with critical growth stages, particularly during flowering and grain filling. Economic analysis indicates potential water savings of 25–40% with marginal yield reductions, but substantial gains in net return under drought scenarios when using drought-tolerant varieties. The findings offer actionable insights for breeding programs prioritizing root architecture, osmotic regulation, and photosynthetic efficiency, and for agronomic recommendations that optimize irrigation scheduling to exploit genotype-specific drought responses. Overall, the integration of drought-tolerant germplasm with strategic irrigation management enhances yield stability and WUE in rain-fed agro-ecosystems, contributing to food security under changing climate and water scarcity conditions.

Project Overview

What This Project Is About

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A plain-language overview of drought-tolerant crop varieties and how they perform under different irrigation levels in rain-fed farming systems. It looks at whether tolerant varieties keep yields steady and use water more efficiently when rainfall is variable.

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The Problem It Addresses

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In many farming areas rainfall is inconsistent, which causes yield drops and wasted water. Traditional crops may fail during dry periods, while drought-tolerant varieties promise steadier yields and better water use. The project investigates if these varieties truly improve stability and water efficiency in real field conditions.

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Objectives of the Project

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1. Explore how drought-tolerant varieties perform under different irrigation levels.
2. Measure yield stability across varying rainfall conditions.
3. Assess water-use efficiency of each variety.
4. Identify practical recommendations for farmers in rain-fed areas.

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What You Will Do Step by Step

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1) Review basic concepts about drought tolerance and water use in crops.

2) Select a few drought-tolerant and standard varieties for a field trial.

3) Set up plots with different irrigation treatments to simulate variable rainfall.

4) Collect data on yield, water use, and key growth indicators.

5) Analyze results to compare stability and water use efficiency between varieties.

6) Summarize findings and discuss practical farming implications.

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Expected Outcome

A clear understanding of which drought-tolerant varieties provide the most stable yields and best water use under different irrigation levels, along with practical guidelines for farmers and researchers.