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

While the world population is steadily growing, the demand for plant-based protein in general, and chickpea in particular, is rising. Heatwaves and terminal droughts 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. Strategic supplemental irrigation can dramatically increase yield when applied at the right time and in appropriate quantities. 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 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 initiation was guided by the plants' leaf water potential (Psi(LWP) > 15 bar) in the field. Our results indicate that the optimal water status (as reflected by pressure chamber values) was 12-14 bar during the irrigation period. Furthermore, adhering to an irrigation strategy based on evapotranspiration with an irrigation factor of 1.2 resulted in the highest grain yields over the three-year study period. To ensure an 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, initiating irrigation 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.