Effect Of Light Quality On Growth And Physiological Characteristics Of Leaf Lettuce And Spanich

In order to investigate the effect of light quality on growth and physiological characteristics of spinach and leaf lettuce, we select the ’Shubo No. 1’ spinach and ’big fast-growing’ leaf lettuce as experimental materials. At the first, using the LED light source, we researched the requirment for different light quality of the spinach and leaf lettuce, then we researched the effect of different color greenhouses films on growth, yield and quality of spinach, in oder to select the appropriate greenhouses films of spinach. The main results as follows:1.we using LED light source, designed four different combinations of three colors of light: white(W), white plus red(WR), white plus blue(WB), white plus red and blue(WRB). The results showed that under white and blue light source, the fresh and dry weight of leaf lettuce increased by 10%, the net photosynthetic rate increased by 21.7%; carboxylation efficiency(EC) and Ru BP carboxylase activity, PSII absorption capacity, capability of capture and transfer electrons of leaves were all higher than that of control; as for nitrogen metabolism of leaf lettuce plant, nitrate reductase and glutamine synthetase activity enhanced, the content of soluble protein and free amino acids also increased. Under white and red light condition, SPS activity increased while SS activity decreased, which means that red light can promote the sucrose synthesis and suppress its degradation. Therefore the contents of soluble sugar and starch increased which facilitated accumulation of carbohydrates and carbon metabolism. In conclusion, supplement of red and blue light to white light can promote growth and photosynthesis of leaf lettuce significantly.2.we using LED light source, designed f Ive different combinations of three colors of light: white(W), white plus red(WR), white plus blue(WB), white plus green(WG), white plus red and blue(WRB). The results showed that under white and red light source, the fresh and dry weight of spinach increased, the net photosynthetic rate, PSII absorption capacity, capability of capture and transfer electrons were all higher than that of control; as for nitrogen content of spinach plant, nitrate reductase and glutamine synthetase activity enhanced, the content of soluble protein and free amino acids also increased. Under white and red light condition, SPS activity increased while SS activity decreased, which means that red light can promote the sucrose synthesis and suppress its degradation. Therefore the contents of soluble sugar and starch increased which facilitated accumulation of carbohydrates and carbon metabolism. In conclusion, supplement of red and blue light to white light can promote growth and photosynthesis of spinach significantly.3.We selected blue, purple, red and white color films to cover the tunnels respectively, which can change the light spectrum ratio inner tunnels. Also, the light intensity were regulated at the same level by coving the plastic net. The results showed that the growth and yield of spinach increased, and the quality of spinach improved under red films. So the red film is more suitable for the grown of spinach.4.We cover the tunnels with red films which have three different luminousness, ie 50%, 60%, and 70% respectively. The results showed that the growth and yield of spinach increased, and the quality of spinach improved obviously under red films with 60% luminousness, which indicate that the 60% luminousness of red film is more suitable for the spinach.