Regulated Deficit Irrigation during Vegetative Growth Enhances Crop Water Productivity in Chickpea (Cicer arietinum L.)

To optimize irrigation, agronomists need to modulate crop water productivity (CWP) throughout phenology. We compared regulated deficit irrigation (RDI) and sustained deficit irrigation (SDI) in chickpea (Cicer arietinum L. var. Blanoro), expecting RDI during vegetative growth (VG) to enhance CWP, as opposed to flowering (F) and pod-filling (PF) stages. The effects of RDI and SDI on grain yield, plant height, weight, grain caliber, pods and grains per plant, harvest index, and CWP, were tested through a complete randomized block experiment during the years 2020 and 2021, comparing full irrigation (FI, ETc = 100%), SDI (SDI₇₅, ETc = 75% during all stages), and six RDI treatments varying in ETc% across phenology: VG₅₀, VG₇₅, F₅₀, F₇₅, PF₅₀, and PF₇₅. VG₇₅ had higher CWP while minimizing impacts on productivity. During 2020, the plants were taller (0.44 ± 4.4 m), and increased in harvest index (0.47 ± 0.06), and CWP (0.90 ± 0.2 kg m⁻³) (p < 0.05), while in 2021, plants were heavier (11.4 ± 2.8 g) and increased in caliber (46.1 ± 3.0 grains); grain yield did not differ between the years (p ˃ 0.05), reaching 861.8 (2020) and 944.7 kg ha⁻¹ (2021). Our results highlight the relevance of maintaining 100% ETc during flowering, and the maintenance of RDI at 75% ETc during vegetative growth.