The selection of drought-tolerant plant genotypes in Iraq

Abstract

Water stress plays a critical role in plant growth and productivity, particularly in crops like maize. Water stress (or drought) can significantly affect plant physiology and development. Absorption vs. loss: Plants absorb water through their roots, but during water stress, the rate of water loss through transpiration exceeds the rate of absorption. This imbalance leads to reduced cell turgor and diminished cellular processes. Cellular impact: When plants are stressed, they may exhibit wilting, reduced cell expansion, and decreased metabolic activity, which affects growth and yield, especially during critical developmental stages. Initially, plants lose more water through transpiration than they can absorb, leading to slight dehydration, which the plant can partially manage through early adaptive mechanisms like closing stomata. As stress intensifies, plants reduce stomatal opening to conserve water, and leads to a decrease in photosynthesis, which affects energy production and growth. Third stage: plants may enter a state of severe dehydration. The stomata are largely closed, photosynthesis halts, and plants may enter dormancy or die. Breeding for drought tolerance. Morphological adaptations: Plant breeders focus on developing drought-resistant varieties through selection and hybridization. Key traits for drought tolerance include. Increased root size: Larger roots help plants access water stored deeper in the soil during dry periods. Reduced leaf area: Smaller leaves reduce water loss through transpiration. Water use efficiency (WUE): Breeding plants with better water use efficiency allows them to conserve water while maintaining growth. This includes focusing on traits like deep root systems: these allow the plant to access water from deeper soil layers.