This two-year study aimed to determine the most appropriate irrigation scheduling and crop water productivity (CWP) of basil plant under controlled conditions in Ferdowsi University of Mashhad, Iran. The experimental layout was a split-plot design with three replications. Three deficit irrigation (DI) levels (DI0: 100%, DI30: 70% and DI60: 40% of the field capacity) and two basil cultivars (Green and Purple) were applied to main and subplots, respectively. The results showed that there was a decrease in yield and an increase in CWP for fresh leaves and fresh and dry herb by decreasing the irrigation water. However, a significant difference between fresh leaves and fresh and dry herb yield of DI0 and DI30 treatment was not observed. The Green basil had higher leaves and herb yield and CWP than other cultivar. A polynomial relationship was stablished between fresh leaves yield and crop evapotranspiration, however the yield response factor (Ky) indicated a linear relationship between the relative reduction in crop evapotranspiration vs. the relative reduction in yield. The Ky values were obtained as 0.70 and 0.76 for Green and Purple basil, respectively. The results revealed that the irrigation regime of 30% water saving could insure acceptable yield of basil plant and increase in CWP, especially for the Green basil cultivar.

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