Adjusting sowing date to enhance roselle performance and water productivity under water deficiency stress

Abstract Climate change induced water scarcity poses a critical challenge to sustainable crop production and an escalating threat to food security, particularly in arid and semi-arid regions Adjusting sowing dates in combination with deficit irrigation to enhance water productivity is a successful adaptation strategy to mitigate the effects of water scarcity on crop production. However, limited information is available on the interactive effects of sowing timing and irrigation levels on roselle ( Hibiscus sabdariffa L.) under arid and semi-arid conditions. In this context, a field experiment was conducted during 2021 and 2022 seasons at the AL-Busili Experimental Farm of the Central Laboratory for Agricultural Climate, Agricultural Research Center in Egypt, to assess the effects of three sowing dates (T1: May 19, T2: June 19, and T3: July 19) and three irrigation regimes (I1: 100%, I2: 75%, and I3: 50% of crop evapotranspiration “ETc”) on growth performance, yield and water productivity of roselle. The treatments were arranged in a split-plot design with three replications. The results indicated that sowing on June 19 (T2) under full irrigation (100% ETc) significantly increased plant height (253.17 cm), branch number (25.74 plant − 1 ), fruit number (100.30 plant − 1 ), and sepal dry weight (18.32 g plant − 1 ). Deficit irrigation (75% and 50% ETc) enhanced anthocyanin accumulation, with the highest value (52.69 mg g − 1 DW) recorded under 75% ETc. Notably, the combination of late sowing (July 19) and severe water deficit (50% ETc) achieved the uppermost water productivity, reaching 1.917 and 1.922 kg m − 3 in the first and second seasons, respectively, despite a reduction in yield. Based on these findings, it could be concluded that the late sowing date can be a viable management strategy in Egypt with limited water availability in terms of water productivity of harvested roselle fruits. These findings highlight a critical comparison between maximizing yield and improving water productivity, suggesting that adjusting sowing date in integration with deficit irrigation can serve as a successful climate adaptation strategy for roselle cultivation in water-limited environments.