Irrigation with simulated oilfield-produced water under semi-arid conditions: growth, seed yield, and oil quality of Moringa oleifera

Abstract

Water scarcity in semi-arid regions motivates the evaluation of unconventional irrigation sources. This study assessed the growth, seed production, and oil quality of Moringa oleifera under irrigation with synthetic saline waters formulated to reproduce the electrical conductivity and major-ion composition of treated oilfield-produced water; no actual produced water was applied. The experiment used a randomized block design in a (3 × 3) + 1 factorial arrangement, with four replicates. Treatments combined three irrigation levels based on crop evapotranspiration (L1 = 33% ETc, L2 = 66% ETc, and L3 = 100% ETc) and three water electrical conductivities (S1 = 0.5, S2 = 2.5, and S3 = 4.5 dS m⁻¹), plus a non-irrigated control. Plant height, stem diameter, dry matter, fruit and seed yield, oil yield, and oil-quality attributes were evaluated. Salinity up to 4.5 dS m⁻¹ did not significantly reduce plant height or stem diameter among irrigated treatments, whereas 100% ETc favored vegetative growth at later evaluations. The highest fruit, seed, and oil yields occurred at 66% and 100% ETc, indicating that 66% ETc can represent a water-saving agronomic compromise when yield is comparable with full irrigation. The 4.5 dS m⁻¹ treatment produced the greatest seed and oil yields. These findings demonstrate moringa tolerance to the tested synthetic saline waters under the experimental conditions, but they should not be extrapolated directly to actual produced water because organic contaminants, trace metals, hydrocarbons, and long-term soil salinization or sodicity were not evaluated.