[Effects of different LED light qualities on growth, photosynthetic characteristics and nutritional quality of savoy].

LED lighting has several unique advantages over traditional lighting, including the ability to control spectral composition, the ability to produce very high light levels with low radiant heat output when cooled properly, and the ability to maintain useful light output for years without replacement. LED light sources have the capability of controlling true spectral composition, allowing wavelengths to match plant photoreceptors to provide more optimal production to regulate plant morphology and nutritional quality. In this paper, the effects of different light qualities on the growth, photosynthetic response and nutritional quality of savoy were studied. With 'Juhua-Xiaobaye' savoy as the test plant, full red light, full blue light, red/blue (3/1) light, red/blue (7/1) light and white/red/blue (3/2/1) light generated by light-emitting diodes were applied with white light generated by fluorescent lamps as control. The results showed that red light could increase biomass and stem diameter, but blue light showed the opposite effect. The chlorophyll (a+b) content was the highest in the red/blue (7/1) light treatment, and chlorophyll (a+b) content was correlated with the red/blue ratio positively. Blue light decreased chlorophyll (a + b) content of savoy, and increased chlorophyll a/b. The photosynthetic rate (Pn) and transpiration rate under red light were the highest, and increased by 43.8% and 55.1% compared with the control. Intercellular CO2 concentration and conductance were the highest under blue light. The fluorescence parameters of the plant were significantly affected by light quality. Values of the maximal photochemical efficiency of PS II (Fv/Fm), Fv/Fo and Phi(PS II) were the highest under white light. Soluble sugar, soluble protein and vitamin C contents were the highest under red, blue and white light, respectively. Comprehensive analysis indicated that red/blue (7/1) light was the best light combination to increase leaf chlorophyll (a+b) content and net photosynthetic rate, as well as plant growth and nutritional quality.