Effects of Different Light Qualities and Intensities of Blue Light on Flowering and Volatiles in Coriander (Coriandrum sativum)

Coriander leaves are widely valued in cooking due to their rich nutrition and unique volatiles, and the flowers are also beneficial for oil extraction from seeds. With the growing interest in LED lights for controlled environments, research on coriander leaves has been reported, but studies on flowers are limited. We investigated the effects of various LED lights, including white (W), red (R), blue (B), and green (G) lights, on flowering. Coriander plants under B light were twice as tall and flowered approximately 4 weeks earlier than those under other lights. However, plants under B light exhibited overgrowth, resulting in fewer flowers at a PAR of 100 µmol·m−2·s−1. To reduce this shade avoidance effect, we tested various combinations of W and B light at a PAR of 120 µmol·m−2·s−1. The 50:50 ratio of W and B light enhanced growth and accelerated flowering, resulting in twice as many flowers as plants under W light. Total volatile compound levels were higher under W light and highest under 50% W and 50% B lights. Key volatiles specific to coriander leaves, such as (E)-2-decenal, 2-undecenal, and 2-dodecenal, were high under G light at 100 µmol·m−2·s−1 of PAR. These findings provide valuable insights into the effects of light on flower development.