Optimizing Jalapeño pepper growth and water use efficiency under deficit and partial rootzone drying irrigation in arid and semiarid regions

Abstract The delicate balance between water availability and demand has reached a critical point, with projections suggesting that future agricultural water demand will likely exceed available resources. Therefore, efficient water use is critical for sustainable agriculture in arid and semiarid regions. This study investigated the effects of deficit irrigation (DI) and partial rootzone drying (PRD) on the physiological performance, yield, and water use efficiency (WUE) of jalapeño pepper ( Capsicum annuum L.) over two growing seasons. Six treatments were applied: full irrigation (FI), DI at 75% and 50% of FI (DI75, DI50), and PRD at 100%, 75%, and 50% of FI (PRD100, PRD75, PRD50), each with three replicates in a randomized complete block design. Despite yield reduction, DI75 (3.5%, 9.6%) and PRD75 (10%, 13.4%) were not significantly different from FI in yield during both growing seasons, 2022 and 2023, respectively. However, yield reduction of DI50 (54.6%, 54.4%) and PRD75 (62.1%, 43.6%) significantly differed from FI during both growing seasons 2022 and 2023, respectively. PRD treatments generally enhanced nutrient uptake and WUE compared to equivalent DI treatments. These findings suggest PRD75 is an effective water-saving strategy for jalapeño pepper production under water-limited conditions.