Excess soil moisture stress in maize: Physiological mechanisms and adaptive strategies

Abstract

Excessive soil moisture, flooding and water logging, presents a major challenge to agriculture and human habitats. These conditions can affect nearly all land areas at some point. Globally, approximately 10% of irrigated farmland is regularly waterlogged, leading to potential crop productivity losses of up to 20%. Rainfed regions are also prone to temporary flooding, exacerbating the issue. Maize, a mesophytic crop, is especially sensitive to waterlogging or stagnant water in its root zone during growth. In Southeast Asia, about 15% of maize-growing areas face such conditions, which severely impact the crop. Excess soil moisture disrupts soil properties and plant processes by reducing oxygen levels and increasing carbon dioxide in the soil, creating reducing conditions. This imbalance affects nutrient availability, promotes the toxic build-up of certain elements, and alters soil microbial activity, all of which hinder plant growth. Prolonged waterlogging can completely halt plant development, ultimately leading to significant yield reductions. These adverse effects stem from disruptions in key plant metabolic processes, including respiration, protein synthesis, sugar metabolism, and the production of metabolic compounds like phytohormones. The extent of damage caused by excess moisture varies across crops and growth stages, as different crops and their varieties respond differently to such stress. However, some morphological, physiological, and biochemical adaptations in plants enhance their resilience to waterlogging. This review delves into the impact of excess soil moisture on soil’s physical and chemical properties and explores the morphological, physiological, and biochemical responses of plants, with a particular emphasis on maize. Studies on other crops are also referenced to provide a broader understanding of the issue.

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