| Summary: | 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 (<i>Cicer arietinum</i> 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 (SDI<sub>75</sub>, ETc = 75% during all stages), and six RDI treatments varying in ETc% across phenology: VG<sub>50</sub>, VG<sub>75</sub>, F<sub>50</sub>, F<sub>75</sub>, PF<sub>50</sub>, and PF<sub>75</sub>. VG<sub>75</sub> 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<sup>−3</sup>) (<i>p</i> < 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 (<i>p</i> ˃ 0.05), reaching 861.8 (2020) and 944.7 kg ha<sup>−1</sup> (2021). Our results highlight the relevance of maintaining 100% ETc during flowering, and the maintenance of RDI at 75% ETc during vegetative growth.
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