Optimization of chickpea irrigation in a semi-arid climate based on morpho-physiological parameters

Abstract

While the world population is steadily growing, the demand for plant-based protein in general, and chickpea in particular, is rising. Heatwaves and terminal drought are the main environmental constraints on chickpea production worldwide. Thus, developing better irrigation management for the chickpea agro-system can promote higher and more sustainable yields. Supplemental irrigation at the right timing and dose can increase yield dramatically. Here, we studied the response of a modern Kabuli chickpea cultivar to supplemental irrigation during the critical pod-filling period over three growing seasons (2019-2021) in northern Negev, Israel, under semi-arid conditions. Six irrigation treatments were applied based on irrigation factors of 0, 0.5, 0.7, 1.0, 1.2, and 1.4 of crop evapotranspiration (ET0) as measured by an on-site meteorological station. Morpho-physiological parameters and above-ground biomass accumulation were monitored throughout the cropping seasons, and the final grain yield was determined at maturation. Irrigation onset was determined based on plants leaf water potential ({Psi}LWP > 15 bar) in the field. Our results indicate that optimal water status (as reflected by pressure chamber values) was 12-14 bar during the irrigation period. Irrigation according to evapotranspiration (ET0) with an irrigation factor of 1.2 resulted in the highest grain yields over the three years. To ensure optimal water supply during the reproductive phase compatible with the crop water requirements, maintaining a 25 mm node length above the last fully developed pod and a 90 mm distance between the last fully developed pod to the stem apex is recommended. In conclusion, irrigation onset when the crop is already at mild drought stress, followed by sufficient irrigation while following the indicated morphology and water potential values, may help farmers optimize irrigation and maximize chickpea crop production. HighlightsO_LIChickpea irrigation is optimized based on meteorological data (ETc) and morphological traits. C_LIO_LIMorphological- not only physiological- traits can capture the dynamics of crop water status. C_LIO_LIIrrigation onset should be at mild drought stress (>15 bar) during the reproductive stage. C_LIO_LIExtending the reproductive phase is essential for grain yield improvement under semi-arid conditions. C_LIO_LIIF=1.2 provides the most productive irrigation regime for chickpea in Mediterranean conditions. C_LI