Abstract

Salinity stress is a major abiotic constraint limiting pepper (Capsicum annuum L.) productivity by disrupting water relations, ionic balance, and metabolic processes. Silicon (Si), although not essential, has emerged as an effective stress mitigator in plants. This study evaluated the potential of exogenous silicon application to alleviate salinity-induced growth inhibition and yield losses in pepper. A pot experiment was conducted under controlled conditions using a Completely Randomized Design with five treatments comprising different silicon concentrations (0, 1, 2, and 3 mM) under salinity stress (6 dS m⁻¹), along with a non-saline control. Morphological, physiological, biochemical, ionic, and yield-related parameters were assessed.
Salinity stress significantly reduced plant height, leaf area, chlorophyll content, relative water content, and yield, while increasing proline accumulation and Na⁺ concentration. Silicon application markedly improved plant growth and physiological performance under salinity. The highest Si dose (3 mM) resulted in maximum plant height, leaf area, chlorophyll retention, antioxidant enzyme activity, K⁺ accumulation, and fruit yield, while significantly reducing Na⁺ uptake and proline content. Enhanced antioxidant defense and improved ionic homeostasis contributed to better stress tolerance. Correlation analysis revealed strong positive associations among growth, physiological traits, antioxidant activity, and yield, while Na⁺ concentration showed a strong negative relationship with yield attributes.
Overall, the findings demonstrate that silicon application effectively mitigates salinity stress by improving water relations, oxidative defense, and nutrient balance, leading to enhanced growth and yield of pepper under saline conditions.