The effect of drought on physiological and agronomic traits of tef [Eragrostis tef (Zucc.) Trotter]

Increased intensity and duration of drought as a consequence of global warming is resulting in increased crop failure and food insecurity. This is particularly prevalent in regions where agriculture is rain fed, as the resultant water deficit in crop tissues as a consequence of insufficient soil moisture to sustain metabolic integrity results in subcellular damage and, ultimately tissue death. Different plants can perceive moisture stress stimuli from their environment and develop adaptive mechanisms to cope with water stress. However, the response of tef [ Eragrostis tef (Zucc.) Trotter], a staple food crop for millions of people in Ethiopia, to varying soil moisture conditions has not been adequately investigated. Therefore, the current study was designed to identify drought-tolerant tef genotypes and their physiological and agronomic adaptation mechanisms of tolerance to moisture deficit at the terminal phenological stage of the plant which aligns to the flowering period. A total of 20 tef genotypes were evaluated for their response to physiological and agronomic traits under well-watered and water-deficit conditions. The results showed significant variation among genotypes, moisture regimes, and their interactions for most measured traits. However, canopy temperature and shoot biomass did not exhibit a significant genotype × moisture regime interaction. In addition, chlorophyll content, normalized difference vegetation index, grain yield, and yield components were significantly reduced by moisture deficit. Although canopy temperature increased under both moisture conditions, the average increase was more pronounced under water-deficit (6.7 °C) than under well-watered (4.7 °C) conditions. Tef genotypes such as Boni, Dtt-2, and Enatite showed higher water use efficiency and intermediate stomatal conductance, indicating adaptive strategies that minimize water loss while maintaining efficient utilization of available soil moisture for metabolic processes, thereby contributing to higher grain yield under stress conditions. The study indicated that tef genotypes employ diverse physiological and agronomic mechanisms to overcome the adverse effects of drought during the flowering or reproductive stage of the plant. However, further studies evaluating diverse genotypes across multiple environments and seasons are needed to validate the findings of the current study. Integrating additional physiological traits, particularly root characteristics, is needed for the development of reliable traits for breeding.