Effects of End of Day Lighting after Night Chilling Treatment on Growth and Development of Lettuce

摘要

Stem elongation and capitulum formation in lettuce is promoted during warm conditions. These morphosis reactions pose a problem to lettuce cultivation as they result in a decreased commercial value. Therefore, the development of the convenient and effective growth control techniques is required to avoid this problem. In this study, night chilling treatment and end of day lighting treatment were examined as potential techniques to reduce the stem elongation and capitulum formation in lettuce. Red and yellow fluorescent lamp were used as light sources in this experiment. Lettuce seeds were sown on May 9, 2013. Seedlings were exposed to low temperature during the night from May 23 to June 6, and sequentially exposed to end of day lighting from June 7 to July 4, 2013. The stem elongation was inhibited by night chilling treatment and was inhibited by end of day lighting treatment remarkably. The capitulum formation was inhibited in the night chilling treatment. These results suggest that end of day lighting after night chilling treatment is effective in suppressing stem elongation and floral stage of lettuce plant.