Preharvest Methyl Jasmonate Treatment Affects the Mineral Profile, Metabolites, and Antioxidant Capacity of Radish Microgreens Produced without Substrate

Abstract

This study investigated the impact of Methyl Jasmonate (MeJA) application on the nutritional content and yield of five different colored radish microgreens. Microgreens were produced without substrate and subjected to 0.5 mM and 1.0 mM MeJA treatments on the 7th day, three days before harvest. The parameters measured included yield, dry matter, minerals, amino acids, secondary metabolites such as chlorophylls (Chls), anthocyanins, flavonoids, phenolics, glucosinolates (GSLs), vitamin C, and antioxidant capacity. MeJA at 1.0 mM generally improved yield and dry weight across cultivars, and all microgreens exhibited rich mineral and amino acid composition, with the influence of cultivar being more significant than MeJA treatment. However, MeJA enhanced all cultivars' anthocyanins, GSLs, phenolics, flavonoids, and antioxidant activities. Generally, as the antioxidant capacity is the primary factor influencing the nutritional quality of microgreens, MeJA-treated microgreens, especially with selected superior cultivars such as 'Asia purple' and 'Koregon red', could offer a potential for cultivation of value-added, eco-friendly microgreens with substrate-free cultivation.

Keywords: MeJA; amino acids; antioxidant capacity; glucosinolates; microgreens; radish; secondary metabolites.

Figure 1

Fresh weight per tray (A) and percentage dry weight (B) of five radish microgreen cultivars, cultivated without substrate and harvested on the 10th day, influenced by the interaction between the cultivars and preharvest MeJA treatment at 0.5 mM and 1.0 mM concentrations applied on the 7th day post-sowing. Vertical bars indicate three replicates’ mean values ± standard error. Different letters on the bars indicate significant interaction differences between cultivars and treatments with Duncan’s mean separation at α = 0.05.

Figure 2

The chlorophyll a (A), chlorophyll b (B), total chlorophylls (C), anthocyanins (D), total glucosinolates (E), total phenolics (F), total flavonoids (G), and vitamin C (H) contents of five radish microgreen cultivars, cultivated without substrate and harvested on the 10th day, influenced by the interaction between the cultivars and preharvest MeJA treatment at 0.5 mM and 1.0 mM concentration applied on the 7th day post-sowing. Vertical bars indicate three replicates’ mean values ± standard error. Different letters on the bars indicate significant interaction differences between cultivars and treatments with Duncan’s mean separation at α = 0.05. Chl and GSLs stand for chlorophyll and glucosinolates, respectively.