What is the role of salicylic acid (SA) in the growth and quality of Swiss chard (Beta vulgaris L.) under an aquaponic system?

Salicylic acid (SA) is an endogenous phenolic phytohormone that plays a key role in regulating various physiological processes, including ion absorption, photosynthesis, plant development, and germination. It has been shown to enhance the production of secondary metabolites in plants, which can improve both sensory properties and nutritional value. In the context of an aquaponic system, where plants are grown using nutrients from fish waste, SA could potentially enhance nutrient absorption and plant growth.

From: "Effects of foliar application of salicylic acid on physiological and qualitative parameters in differently colored Swiss chard (Beta vulgaris L. ssp. cicla) under an aquaponic system", Journal of Agriculture and Food Research, Volume 22, August 2025, 102140

The study found that the application of salicylic acid (SA) had varying effects on the growth and quality of Swiss chard, depending on the irrigation strategy and the color of the chard. The white chard variety responded more favorably to the treatments, particularly with the 50/100+SA treatment, which resulted in greater plant weight, higher total phenolic content, and lower lipid peroxidation. In contrast, the red chard variety showed poor tolerance to the applied dose of SA. The findings suggest that SA can enhance the growth and nutritional quality of white chard under specific irrigation conditions in an aquaponic system.