The Effects of Different Water Deficit Levels on Yield and Water Use Productivity of Sesame Irrigated by Subsurface Drip Irrigation

Abstract

In arid and semi-arid regions, subsurface drip irrigation effectively maximizes crop yield, water efficiency, water productivity, and fertilizer effectiveness. This study evaluated the impact of subsurface drip irrigation (SDI) at different lateral depths (D1: 20 cm, D2: 30 cm, D3: 40 cm) on sesame (Muganl & imath;-57) yield, yield response factor, water productivity (WP), irrigation water productivity (IWP), Gross economic irrigation water productivity (GEWPI) and net economic irrigation water productivity (NEWPI) under deficit irrigation conditions in a Mediterranean climate. Conducted during the 2019 and 2020 growing seasons, the study performed the effects of deficit irrigation treatments, including full irrigation I1 (I1: 1.00), 70% of I1 (I2: I1 x 0.70), 50% of I1 (I3: I1 x 0.40), and rainfed condition (I4). The average crop evapotranspiration (ETc) was computed as 339, 241 and 144, and 14 mm for D1 at I1, I2, I3, and I4 respectively; ETc in the treatment of D2 were 263, 189, 114, and 14 mm; and those in the treatment of D3 were 257, 184, 111, and 14 mm, respectively. The highest WP resulted in the treatment of D3I2 as 8.4 and 9.0 kg m-3 in 2019 and 2020, respectively. In contrast, the lowest WPs (4.2 and 4.6 kg m-3) were obtained in the treatment of D1I1in the same experimental years. The highest IWPs (12.5 and 13.1 kg m-3) resulted in D3I2 in 2019 and 2020, respectively. The lowest IWPs (5.1 and 5.6 kg m-3) were computed in the treatment of D1I1 for the same years, respectively. Also, GEWPI, considering the gross profit margin obtained during the sesame growing season, the amount of IWU showed the highest result in rainfall condition applications. NEWPI showed similar results with GEWP. The seasonal yield response factor (Ky) was 1.27 and 1.21 in the experimental years. In conclusion, the findings of this study highlight the significant impact of lateral depth in subsurface drip irrigation on evapotranspiration and water and irrigation productivity in Muganl & imath;-57 sesame cultivation. The results indicate that optimizing lateral depth, particularly at 40 cm with mild water stress conditions (I2), can enhance water productivity and overall crop performance under Mediterranean climate conditions.