Adding different proportions of red/blue = 3/1 to white light affects eggplant seedling quality by regulating leaf morphology and photosynthetic system

Owing to the increase in planting areas of protected vegetables and global climate change, the improvement of light quality has become a topic of interest in the modern vegetable seedling industry. Our previous work showed that red and blue combined light (red (R)/blue (B) = 3/1 was beneficial to eggplant seedling growth, and the addition of 60% R/B = 3/1 light to white light could significantly increase the seedling index. To explore the underlying physiological mechanism, the morphology and photosynthetic index of the leaves of eggplant seedlings under different light treatments were analysed. The proportions of (R/B = 3/1) light to white light were 20% (T1), 40% (T2), 60% (T3), 80% (T4), and 100% (T5), and white light was used as the control (CK). The results showed that most leaf morphology and photosynthetic indicators were increased under different proportions of R/B = 3/1 light, especially under T3 treatment. T3 treatment up-regulated the key genes of phytochromes ( SmphyA, SmphyB ) and photosynthesis ( SmpsbA , SmrbcS , SmrbcL , SmLHCII ) to increase the efficiency of photosynthesis. However, ABS/RC, DIo/RC, TRo/RC, CSP, and GO activity decreased after the addition of R/B = 3/1 light. In conclusion, the addition of 60% R/B = 3/1 light to white light was the most beneficial in eggplant seedling growth by improving the photosynthetic system.