Balancing Yield and Antioxidant Capacity in Basil Microgreens: An Exploration of Nutrient Solution Concentrations in a Floating System

The appropriate concentration of the nutrient solution (NS) plays an important role in the yield, antioxidant capacity, and biochemical compounds of basil microgreens in the floating system. This study examined the impact of five different concentrations of Hoagland’s NS (25%, 50%, 75%, 100%, and 125%) on the antioxidant capacity, biochemical compounds, and yield of four basil cultivars and genotypes (Persian Ablagh, Violeto, Kapoor and Red Rubin) in a floating system, utilizing a split plots designs. Results revealed that the highest yield was achieved with a 50% NS concentration. The Persian Ablagh genotype, under a 125% NS concentration, exhibited the highest content of carotenoids, flavonoids, phenolic compounds, and antioxidant potential index (APCI). The Violeto cultivar at a 100% NS concentration produced the highest amounts of vitamin C and anthocyanin. The Kapoor cultivar, when grown with a 100% NS concentration, demonstrated the greatest antioxidant capacity. The nutrient solution with 125% concentration compared to 50% concentration reduced the yield by 23.29%. Also, the performance of the Violeto cultivar increased by 36.24% compared to the red variety of Robin. According to the APCI index, the genotype of Iranian Ablaq basil increased by 152.79% in the treatment of nutrient solution with a concentration of 125% compared to 50%. In this study, yield and total chlorophyll showed a significant negative correlation. A significant positive correlation was observed between vitamin C content and flavonoids, anthocyanin, phenolic compounds, and antioxidant capacity. Anthocyanin content exhibited a positive and significant correlation with the APCI. Based on these findings, we recommend a 50% NS concentration of Hoagland’s NS for optimal yield, a 125% NS concentration for the production of secondary metabolites with enhanced antioxidant capacity, and a 100% NS concentration as a balance between antioxidant properties and yield for basil microgreens production in a floating system.