Photoperiodic effects on the growth and yield of Coixlacryma-jobi L. cultivar

Coixlacryma-jobi L. is a very useful medicine and widely used for various human diseases such as abdominal tumors, cancer, and respiratory tract infections. However, its growth and yield response to different photoperiods has not been studied yet. In this study, three periods (three-leaf, five-leaf, and eight-leaf) and two shading treatment periods (8 and 11 hours daylight) were designed to investigate the effects of photoperiod on the growth and yield of Coix cultivars in Sichuan China. Four cultivars were selected and obtained from Beijing, Shandong, Nanjing, and Ya’an, respectively. Several agronomic characteristics of Coix, such as tillers, effective tillers, leaf number, plant height, and yield traits, were recorded. The results indicated that Beijing cultivar was more sensitive to light than other cultivars on the short-day growth rate. Southern cultivars show earlier daylight sensitivity than northern cultivars, while daylight length of the northern cultivars was longer than that of southern cultivars. For plant height, photoperiod had more impact on Coix at the earlier period than the late period. The three-leaf period was more sensitive to daylight than the five- and eight-leaf period, and the longer shading treatment of the three-leaf period promoted Coix to produce more tillers. Our study reveals that shading treatment shortens the growth of Coix and can accelerate the transition from nutritive to reproductive growth. It was found that photoperiod had a significant influence on the growth of Coix but exhibited no influence on its yield.