Effect of Deficit Irrigation Technique on Black Cumin (Nigella sativa L.) Water Use Efficiency

To increase the agricultural profit, an experiment was conducted at the Scientific Agricultural Research Center (SARC) at Salamiyah, Syria. The experiment aimed to estimate the optimum irrigation level that maximizes productivity as well as the black cumin's quality local quality standards under experimental conditions. The irrigation treatments were 25, 50, 75 and 100% of the Potential Evapotranspiration (ETP) based on Class-A pan evaporation. The treatments were denoted as B, C, D and E, respectively. The no-irrigation treatment (A) was considered as control. Irrigation water was applied by a drip system. The A-E treatments were designed and implemented using complete randomized block design (CRBD) with four replications. The actual Evapotranspiration (ETa) was calculated after calibration of soil using SPAW software. Furthermore, crop yield, Irrigation Water Use Efficiency (IWUE), yield response factor (ky) and some parameters (period of growth stage, date of flowering…etc.) were studied during 2018-2019 successive growth seasons. Results showed that irrigation could be scheduled using some equations and Class-A pan evaporation. Moreover, the vegetative growth parameters flourished virtually and significantly by comparing higher and lower irrigation levels. However, Irrigation Water Use Efficiency (IWUE) values increased by reducing the applied irrigation water. Treatment B recorded the highest IWUE value (2.4 kg ha-1 mm-1), but key values remained less than 1.0, indicating that the plant tolerates drought. Furthermore, treatment C scored the top-seed (130.6%) concerning the profit/total costs ratio. Finally, based on the results, we recommend that irrigation should not be more than 75% and not less than 25% of the ETP.