Mixed red and blue light promotes ripening and improves quality of tomato fruit by influencing melatonin content

Abstract

With regard to plant growth and development, red (R) and blue (B) light are essential light qualities. Moreover, it has been previously reported that melatonin has an effect dominates regulating fruit ripening. Nevertheless, people know little about the specific mechanism by which R and B light regulate melatonin levels and fruit ripening in tomato (Solanum lycopersicum L.). In this research, the effect of R and B light on changes in endogenous melatonin levels and fruit quality during tomato ripening involved monochromatic light of white (W, control), R, B and mixed R and B (RB) light was investigated. According to the findings, melatonin decreased with the fruit ripening, which was accompanied by enhanced levels of fruit softening, ethylene biosynthesis, respiration rate and lycopene accumulation, as well as the conversion of carbohydrates. Furthermore, compared to monochromatic R and B light, RB light noticeably enhanced the melatonin content in tomato fruit, which promoted the ripening of tomato fruit consequently and led to accelerated fruit softening as well as upregulation of ethylene and lycopene biosynthesis, respiration rate, antioxidant activity and carbohydrate accumulation. It is concluded that RB light may regulate endogenous melatonin, thus promoting fruit ripening and quality improvement of tomato through cross-talk with other biomolecules, by increased ethylene production and signaling.