Abstract
INTRODUCTION: The yield and quality of tomato (Solanum lycopersicum. L) are often decreased when plants suffer from low light intensity and short-photoperiod in winter. Manipulation of the artificial light environment is a feasible technology to promote off-seasonal production and improve fruit nutritional quality in the greenhouse. OBJECTIVES: Here we aim to investigate the appropriate balance between red (R) and blue (B) light to improve tomato yield and quality traits. METHODS: Biochemical, molecular and genetic analysis were used to study the photosynthetic traits, pigments, sugar and volatile accumulation pathway genes. RESULTS: Tomato plants subjected to R1B0.8, a ratio between monochromatic red (R) and blue (B) light, for 16 h photoperiod showed significantly increased chlorophyll and biomass accumulation compared to white (W) light treatment. R1B0.8 light treatment enhanced electron transfer efficiency and photosynthetic capacity by improving the light energy utilization rate and inducing photosystem core subunit genes (SlPsaC, SlPsaB, SlPsaA) and light-harvesting complex genes (SlLHCB/A). Compared to W light, R1B0.8 light also induced carotenoid accumulation and accelerated fruit ripening, which was associated with the upregulation of carotenoid biosynthesis genes (SlPSY1, SlPDS) and ethylene biosynthesis genes (SlACS2, SlACO2) in tomato fruits. Moreover, fruits exposed to R1B0.8 light treatments significantly improved fructose and glucose accumulation and the expression of the volatile-related gene (SlAADC1a) and flavor-related gene (SlGORKY). CONCLUSION: Our results showed that R1B0.8 light with a 16 h photoperiod could prominently promote photosynthetic traits, pigments, sugar and volatile accumulation in tomato. Our findings on the manipulation of artificial light environments in protected horticulture offer possibilities for enhancing crop yield and quality to meet the increasing global demand for food.