Rice yield corresponding to the seedling growth under supplemental green light in mixed light-emitting diodes

Abstract

The objective of this study was to investigate the effect of different supplemental intensity of green light in mixed light-emitting diodes (LEDs) on rice (Oryza sativa L.) seedling growth, and their after-effect on grain yield. The rice seedlings were nursed in greenhouse with 30-days continuous supplemental lighting (6 h/day) from three light sources: 75% red + 25% blue (photon flux density) LED (RB), 62.5% red + 25% blue + 12.5% green LED (RBG12.5) and 50% red + 25% blue + 25% green LED (RBG25), and then transplanted into paddy field in two consecutive years (2014 and 2015). The results showed that both shoot and root growth of rice seedlings were enhanced by the addition of green light into red and blue LEDs, but the response of different organ systems depended on the intensity of green light. The low percentage of green light in the light source (RBG12.5) could not only promote the stem elongation, the shoot dry weight accumulation and the root respiration activity but also could change the root morphology (indicated by the total surface area and the average diameter of root), while the high percentage of green light (RBG25) only changed the root morphology and increased the root respiration activity. The influence of light on rice during the seedling stage extends to the end of the maturity stage, with the highest rice grain yield, spikelets per panicle and the grain filling percentage in RBG25.