Effects of ศight on Growth and Flowering of Green Perilla Grown in Closed System

Abstract

Green perilla or shiso (Perilla frutescens (L.) Britton) is a culinary herb for cooking and dish decoration. Shiso is a short-day plant that light supplement is necessary for prolong vegetative growth and delay flowering. This research consists of 2 parts of the experiments in order to clarify the effect of light duration per day and the effect of LEDs light supplement on flowering of shiso; 1) study of the effect of light duration (11, 12, 13, 14, 15, 16 h) from white fluorescent light, 120 µmol m^-2s^-1, on flowering time of shiso 2) study of the effect of supplemented light spectrum (white, red, blue and red and blue combination) from LEDs 12 µmol m^-2s^-1, 4 h following white LED 120 µmol m^-2s^-1, 12 h on growth and days to flower of shiso. The experimental design was completely randomized (CRD)  with 3 replications per treatment and six plants per replication. Shiso plants were grown in a closed room with controlled air temperature at 25 ^oC and relative humidity of 65-70%. The results showed that the application of white fluorescent light for 15-16 h per day delayed days-to-flowering of shiso up to 180 days after transplanting (DAT). For the LED light spectrum experiment, the red-LED light strongly promoted the average number of leaves (21.25 leaves) and the combination of red and blue light promoted the plant average height (87.14 cm) which were significantly different from the white LED which the plant had 15 leaves and 64.58 cm in plant height, respectively. However, the white LED considerably had the longest the days-to-flowering of 103.58 DAT, while the blue-LED had only 49.17 DAT