# Optimization of light spectrum and intensity to enhance growth and metabolite profiles in green and purple radish microgreens cultivated in a vertical farming system

## TL;DR

This study shows how adjusting light color and brightness in vertical farms can improve the growth and nutritional content of radish microgreens.

## Contribution

The study identifies optimal light conditions for maximizing yield and nutritional quality in green and purple radish microgreens.

## Key findings

- AP673L LED light with R:B ratio 5.5 at 300 μmol maximized yield and dry matter in both radish cultivars.
- NS12 LED light with R:B ratio 1.9 at 300 μmol maximized sugar and organic acid accumulation in green radish.
- Glucosinolate content varied by light spectrum and radish cultivar, with green radish responding better to lower R:B ratios.

## Abstract

Microgreens have emerged as a promising crop in vertical farming due to their high nutritional value and short growth cycles. Light spectrum and intensity are critical factors influencing biomass production and metabolic activity in plants, particularly in controlled environments such as vertical farming systems. This study aimed to evaluate the combined effects of light spectrum and intensity on the agronomic traits and metabolite profiles of green and purple radish (Raphanus sativus L.) microgreens.

Three commercial LED spectra – NS12 (R:B = 1.9), Ph2.1 (R:B = 2.1) and AP673L (R:B = 5.5) – were tested at three intensities (100, 200, and 300 μmol m−2 s −1) in a controlled vertical farming system. Growth parameters (yield, dry matter percentage (DMP), leaf area), photosynthetic pigments, sugars, organic acids, and glucosinolates were quantified. The highest R:B ratio (5.5) under the AP673L lamp at 300 μmol m−2 s−1 significantly enhanced yield and DMP in both cultivars, while the lowest R:B ratio observed in the NS12 lamp at the same intensity maximized sugar and organic acid accumulation in green microgreens. Glucosinolate content was spectrum‐ and cultivar‐dependent: green radish accumulated higher levels under the lowest R:B ratio (NS12), whereas purple radish responded better to the R:B = 2.1 ratio under the Ph2.1 lamp at lower intensities.

These results demonstrate that optimal light strategies in vertical farming must be tailored to specific microgreen genotypes and light conditions to simultaneously maximize productivity and nutritional quality. © 2026 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.