Enhancing Drought Stress Tolerance in Wheat through Phosphorus and Zinc Management

Document Type : Research Paper

Authors

• Pouriya Tohidtalab ¹
• Hossein Mirseyed Hosseini ¹
• Seyed Majid Mousavi ²

¹ Department of Soil Science, College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran

² Soil and Water Research Institute (SWRI), Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran

Abstract

Keywords

• Nutrition Management
• Rhizosheath
• Water Deficit Stress
• Wheat

Main Subjects

• ..

Introduction

Water deficit stress is one of the most critical abiotic factors limiting plant growth and agricultural productivity worldwide. Its impact is particularly severe in arid and semi-arid regions such as Iran, where annual precipitation is significantly lower than the global average and access to freshwater resources is limited. Drought stress disrupts physiological, biochemical, and morphological processes in plants, leading to reduced photosynthesis, impaired nutrient uptake, oxidative damage, and ultimately lower yields. To cope with such stress, plants employ various mechanisms including osmotic adjustment, hormonal regulation, antioxidant defense activation, and rhizosheath formation, a soil layer adhering to roots that enhances water and nutrient absorption under dry conditions. Among agronomic strategies to mitigate drought effects, nutrient management plays a pivotal role. Balanced and targeted application of essential nutrients can improve plant resilience and maintain productivity under stress. Phosphorus (P) and zinc (Zn) are two key elements involved in root development, membrane stability, water relations, and enzymatic functions, making them crucial for enhancing drought tolerance.

Objective

This study aimed to evaluate the effects of phosphorus and zinc application, both individually and in combination, on the growth and drought resistance of two wheat cultivars with contrasting drought sensitivity. The research focused on comparing soil application and seed priming methods to determine the most effective nutrient delivery strategy under water deficit conditions.

Methodology

The experiment was conducted during the summer of 2024 in the research greenhouses of the Soil and Water Research Institute in Alborz Province, Iran. A factorial experiment was arranged in a completely randomized design with four factors and three replications, totaling 192 experimental units. The first factor was soil application of phosphorus and zinc in four levels: no application (control), phosphorus (12 mg/kg) only, zinc (2 mg/kg) only, and combined phosphorus and zinc. The second factor was seed priming with the same four levels. The third factor was irrigation regime: optimal irrigation at 100% field capacity and deficit irrigation at 50% field capacity. The fourth factor was wheat cultivar: Tajan (drought-sensitive) and Heydari (drought-tolerant). Fertilizer rates were determined based on soil test results, and seed priming was performed using a standardized concentration of 10Zn/10P₂O₅ (w/w) per 2 kg of seed. Morphological and physiological traits including shoot and root dry weight, shoot height, root length, relative water content (RWC), rhizosheath weight, and biomass allocation ratios were measured. Statistical analysis was performed using SAS 9.4 software, and mean comparisons were conducted using Duncan’s test at P ≤ 0.05.

Results

Drought stress significantly reduced morphological traits and yield components in both wheat cultivars. However, soil application of phosphorus and zinc under deficit irrigation conditions led to remarkable improvements in plant performance. Dry weight of shoots and roots increased by 400–500%, while shoot height and root length rose by 50–130%. Relative water content showed a 200% increase in stressed plants receiving combined soil application of phosphorus and zinc. Zinc application via soil had the most pronounced effect on rhizosheath formation, indicating its role in enhancing root-soil interactions and water uptake under drought. Comparatively, nutrient delivery through soil was more effective than seed priming in improving drought tolerance. Biomass allocation indices such as root-to-shoot ratio, shoot biomass allocation ratio, and rhizosheath mass ratio revealed that phosphorus and zinc application moderated biomass distribution, contributing to better stress adaptation. The drought-tolerant cultivar Heydari consistently outperformed Tajan across most measured traits, but both cultivars benefited from nutrient treatments.

Conclusion

The findings demonstrate that strategic nutrient management, particularly simultaneous soil application of phosphorus and zinc, significantly enhances drought tolerance in wheat. This approach improves root development, water retention, and biomass allocation, thereby mitigating the adverse effects of water deficit stress. Given the increasing frequency of drought events and the importance of wheat as a staple crop, integrating phosphorus and zinc management into agronomic practices offers a practical and effective solution for sustaining wheat production under challenging environmental conditions.

Authors Contribution

Porya Tohid talab; design and conducting the experiments and data collection writing first draft

Hossein Mirseyed Hosseini: supervision and experimental arragements editing final draft

Seyed Majid Mousavi: experimental design and facility, supervision and control of the data collection and final results

Data Availability Statement

The datasets generated during and/or analysed during the current study are available from the corresponding author on reasonable request.

Acknowledgements

The authors sincerely appreciate the efforts and support provided by Soil and Water Research Institute (SWRI), Karaj, Iran.

Ethical considerations

Not applicable.

Conflict of interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.