Effects Of Different LED Light On The Growth And Physiological Characteristics And Nutritional Quality In Savoy

LED lighting systems have 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. Light emitting diodes represent a promising technology for the greenhouse industry that has technical advantages over traditional lighting sources. LEDs are the first light source to have the capability of true spectral composition control, allowing wavelengths to be matched to plant photoreceptors to provide more optimal production and to influence plant morphology and composition. In addition, using LED light source can be a single wavelength of light quality, it can solve the problem of impure quality in previous studies and increase the reliability of test results. In Protected cultivation condition, Due to a large amount of nitrogen fertilizer, the weak and uneven illumination and other factors accumulate nitrates, so the quality of leaf fall hazard to human health. The growth period of research dynamic of savoy has not been reported using LED light source. The paper studied the effects of different light qualities on the growth, photosynthetic response and nutritional quality of savoy, in order to determine the effect of light quality on savoy physiological characteristics and nutritional quality and produce high yield and quality of light dishes savoy quality environmental regulation provides theoretical support for the cultivation and other leafy vegetables provide a reference light quality environmental regulation."JuHua-Xiaobaye" savoy as material, red light, blue light, red/blue (3/1) light, red/blue (7/1) light and white/red/blue (3/2/1) light generated by light-emitting diode were applied. And white light generated by fluorescent lamps was used as control. The results showed that:1. Light quality had significant effect on growth and development of savoy. The biomass, stem diameter and aboveground and underground part fresh weight were the highest under red light. It was concluded that the red light can enhanced the growth and yield of savoy. Compared with controls, mixed light also can promote the growth of significant savoy, but the live weight, stem diameter and aboveground and underground part fresh weight were the minimum under blue light, that blue light is not conducive to the growth of savoy to lower yields.2. Light quality had great effects on Physiological characteristics of savoy. As the savoy were growing, the chlorophyll content always firstly increased and then fell. The contents of chlorophyll (a+b) was highest under red/blue (7/1) light treatment, and chlorophyll (a+b) contents were correlated with red/blue ratios positively. The chlorophyll (a+b) content of savoy with blue light supplement was lowest among the treatments, but chlorophyll a/b was increased significantly under blue light. The photosynthetic rate (Pn) and transpiration rate (Tr) under red light were the highest, and were43.78%and55.12%higher than that under white light. Whereas intercellular CO2concentration (Ci) and conductance (Gs) were the highest under blue light. The fluorescence parameters were significantly affected by light quality. Values of the maximal photochemical efficiency of PS II (Fv/Fm), Fv/F0and ΦPSⅡ were the highest under white light. SOD activity with the extension of the general illumination time gradually increased, and subsequently reduce small amplitude, SOD activity is always higher than other treatments under red light, blue light in the red and blue mixed light irradiation also help to improve the SOD activity. POD activity with prolonged exposure time gradually increased, red light irradiation significantly increased the activity of POD and Blu-ray have the opposite effect. CAT activity trends and POD activity contrary, with prolonged illumination gradually decreased, blue with red promote CAT activity inhibition effect of promoting the mixing of light better than red light. Similar trends APX and SOD, as a whole showed decreased after the first increase, and the red light was significantly higher than other treatments, blue light reduced APX activity.3. Light quality had significant effect on nutritional quality of savoy. The contents of soluble protein, soluble sugar and free amino acid in different light quality in whole growth period increased gradually then came down in the later. The soluble sugar content was the hightest under red light among the treatments. The contents of soluble protein and free amino acid were the highest greatest under blue light. The contents of nitrate and Vc in different light quality in whole growth period came down gradually then increased in the later. The nitrate content was the lowest under red light among the treatments. The nitrate content was significantly lower than control in red and blue wavelengths, it was the highest under blue light treatment. Red or blue light was bad for the synthesis of Vc, Vc content is higher under white light. As savoy growth collapsed, crude fiber content increased gradually, it was in the highest under red light, red light blue mixed times, minimum under blue light.