Effects of Water Stress and Mulch Type on Linseed Seed Yield, Physiological Traits, and Oil Compounds

The effects of three mulch types (vermicompost, plastic, and straw) plus an untreated control, in factorial combination with three irrigation regimes (RFD: rainfed condition; SIF: one supplemental irrigation at the flowering stage; SIVF: two supplemental irrigations at the vegetative and flowering stages) on linseed growth, seed yield and oil composition, and biochemical status were investigated. Linseed plants under two irrigations and straw mulch showed the highest seed yield (300 g and 222.4 g m-2, respectively), biological yield (887.9 g m-2), and concentration of oleic and linoleic acids. The plastic mulch application under rainfed conditions or one irrigation increased stearic and palmitic acid concentrations, respectively. Water deficit stress encouraged the accumulation of proline (10.1 μmol g-1 fresh weight (FW)), total phenols (6.68 mg g-1 FW), and DPPH radical scavenging capacity (56.5%). Plants grown in straw mulched soil showed the highest total phenol content and DPPH radical scavenging capacity, while control plants displayed the highest proline concentration. Enzyme activities, including catalase and superoxide dismutase, were enhanced under straw and plastic mulch compared to control plants under rainfed conditions. Our findings suggest that straw mulch represents an effective, sustainable strategy to successfully manage linseed crops, mitigating the adverse effects of water deficit stress on plant performance.