Sustainable Management of Alkaline Stress using Clove Fruit Extract in Tomato

Abstract

Alkalinity stress is a critical abiotic factor that affects tomato (Solanum lycopersicum L.) growth and productivity by inducing nutrient imbalance, oxidative damage, and physiological dysfunction. This study investigated the potential of clove (Syzygium aromaticum) fruit extract (CFE) as a sustainable bio-stimulant for improving tomato tolerance under alkaline conditions. A factorial pot experiment was conducted with two alkalinity treatments (0 and 100 mM NaHCO₃ + Na₂CO₃ in a 9:1 ratio) and five foliar CFE concentrations (0%, 0.5%, 1%, 3%, and 5%) in a completely randomized design with three replications. Plant growth, physiological characteristics, biochemical responses, antioxidant enzyme activities, and yield attributes were evaluated. Alkalinity stress significantly reduced shoot and root growth, leaf area, biomass accumulation, chlorophyll content, relative water content, and fruit yield while increasing electrolyte leakage and oxidative stress. However, CFE application substantially improved plant performance under alkaline conditions, with optimal responses observed at moderate concentrations. CFE enhanced photosynthetic stability, improved water status, and stimulated antioxidant defense mechanisms by increasing the activities of superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD), thereby reducing oxidative damage. Furthermore, CFE-treated plants showed improved fruit development and yield recovery compared with untreated stressed plants. These findings demonstrate that clove fruit extract is an effective, eco-friendly bio-stimulant for mitigating alkaline stress and enhancing tomato resilience, offering a promising strategy for sustainable crop production in degraded soils.