Abstract:

Tomato was planted in the artificial light plant factory and exposed to different light treatments. Pure red light was as the control, and set up two blue light intervention methods under red background light. One was blue light supplementation intervention with intensity of 32，40，64 and 80 μmol·m⁻²·s⁻¹ respectively, namely R/RB₃₂, R/RB₄₀, R/RB₆₄ and R/RB₈₀，and the other was blue light substitution intervention with the intervention time intervals of 0, 1min, 1h, and 4h respectively, namely RB, R/RB_(1min) R/RB_(1h) and R/RB_(4h). The growth, antioxidant system and fluorescence characteristics were analyzed to investigate the effects of different light modes of red and blue light on tomato seedling. The result showed that: (1)compared with pure red light, blue light supplementation intervention reduced tomato plant height by 9.94% to 19.62%, but blue light substitution intervention increased tomato plant height by 12.29% to 36.31%. (2)Biomass of tomato seedlings were both increased under two blue light intervention modes, and the shoot biomass was increased with the increase of supplementary blue light intensity. Among which, the highest dry weight and fresh weight were both detected under R/RB₈₀ blue light supplementation intervention treatments, which were enhanced by 115.45% and 198.35% respectively, while the highest dry weight and fresh weight were both observed under R/RB_(1min) in blue light substitution intervention treatments, which were enhanced by 119.35% and 152.31% respectively, compared to the control (P＜0.05). (3)The activity of superoxide dismutase (SOD), catalase (CAT) were both increased under R/RB₈₀ treatment, while the content of active oxygen (ROS) was decreased in tomato leaves. R/RB_(1min) treatment increased the activity of CAT in stems and leaves by 2.84% and 18.35% respectively, while ROS content was decreased by 4.64% and 20.8% respectively, compared to the control. (4)Blue light intervention modes both improved fluorescence parameters such as Ψ_o (the probability of excitons captured by the reaction center transferring electrons to the primary quinone acceptor (QA) and then to other electron acceptors), F_v/F_m (maximal photochemical efficiency), F_v/F_o (potential photochemical efficiency), ET_o/RC (the energy captured by the unit reaction center for electron transfer), while reduced DI_o/CS (thermal dissipation of photosynthetic system). Moreover, the fluorescence parameter values under blue light supplementation mode were mostly higher than those under blue light substitution mode. The values of TR_o/RC (the energy captured by the unit reaction center for reducing QA), ET_o/CS (quantum yield of electron transfer per unit area), and ET_o/RC were the highest under R/RB₈₀ treatment, which were increased by 0.5%, 0.6%, and 2.1% respectively compared to the control. PI_abs (leaf photosynthetic performance index), ET_o/RC, and Ψ_o were increased by 17.02%, 9.53%, and 5.44% under R/RB_(1min) treatment, respectively, compared to the control. Overall, the electron transfer efficiency of tomato leaf photosynthetic system was improved under blue light intervention with red light background, which was beneficial for seedling morphology and biomass increase. Among which, R/RB₈₀ and R/RB_(1min) treatments were the better treatments in this experiment.

Key words: Tomato seedlings, LED, Grow, Antioxidant enzyme, Chlorophyll fluorescence