Effect of far-red light applied at the end of the day in red and green leaf lettuce cultivars grown under two types of white LED

Key words: cultivar difference, end of day, far-red LED, stem elongation. The growth and yield of 13 red and green leaf lettuce (Lactuca sativa L.) cultivars were evaluated under two types of white LED irradiation. There was a difference in growth under the two types white LEDs, specifically in the fresh total weight, fresh leaf weight and dry weight in all cultivars. In addition, the main stem elongation was confirmed for red and green lettuce cultivars under all treatments, but some cultivars promoted the growth of the main stem and the others were inhibited by treatment with far-red light applied at the end of the day (EOD-FR). Furthermore, the EOD-FR treatment affected the characteristic reactions due to white LED light quality in each of the cultivars. These results showed that it is necessary to investigate the selection of white LEDs with and without EOD-FR treatment for each lettuce cultivar.