Silicon enhances photosynthetic pigment accumulation and antioxidant defence in nasturtium under shade and semi-shade conditions

Silicon (Si) is recognized for enhancing plant stress tolerance, its physiological role in alleviating low-light stress in ornamental species remains poorly understood.This study evaluated the effects of foliar-applied Si (0, 50, and 100 μM) on growth, photosynthetic pigments, antioxidant metabolism, osmolyte accumulation, and flowering of nasturtium grown under shade and semi-shade conditions.Silicon application significantly increased plant biomass, leaf production, flower size, flower fresh weight, and floral yield, particularly at 100 μM.These improvements were associated with enhanced chlorophyll accumulation, increased activities of superoxide dismutase, peroxidase, and catalase, elevated ascorbic acid and total phenolic contents, and greater accumulation of proline and glycine betaine.Hence, Si enhances low-light tolerance by improving photosynthetic capacity, antioxidant defense, and osmotic adjustment, thereby promoting vegetative growth and floral productivity.