Effect Of Different Light Emitting Diode Sources On Tomato Physiological Characteristics And Fruit Quality During The Process Of Color-changed

Red light, blue light, red + blue(R+B) light generated by light-emitting diode were applied during tomato color-changed period, and white light generated by fluorescent lamps as control. The effects of different lights quality on physiological characteristics and fruit quality of tomato (982, CaiDu5) during color-changed period were studied. The main results were as following:1. Different light emitting diode sources had significant effect on growth and development of tomato. The plant height was the highest under R+B light and the lowest under blue light. But under the blue light, the stem diameter was the hightest. The two cultivars were treated under red light had the most photosynthesis rate and the leaf numbers, and the lowest intemode length. It was concluded that the red light can enhanced the vegetative growth, and the plant became stronger under the blue light.2. There are more differences of tomato fruit commodity quality among the light emitting diode sources. The tomato fruit shape indexes was the highest under blue light, and the fruit firmness was the lowest under red light. The chlorophyll content decreased while the other pigments increased gradually during whole growth period. The lycopene content was the highest under red light among the treatments. The contents of anthocyanin, flavonoids, chlorophyll, and carotenoid were the highest under blue light. The R+B light accelerated the anthocyanin formation, but inhibited the flavonoids foemation.3. Different light emitting diode sources had significant effect on tomato fruit nutritional quality. The contents of the vitamin C (Vc), soluble protein, soluble sugar and titratable acid in different light quality in whole growth period increased gradually then decreased in the later. The Vc content was lowest under red light among the treatments. The contents of Vc and soluble protein were significantly increased under blue light. There was no obvious difference in Vc content between R+B light treatment and the control, but R+B light had the superiority in promoting the content of soluble protein. The red light and R+B light were the most effective for the accumulation of the soluble sugar and titratable acid.4. Different light emitting diode sources had different effects on tomato fruit flavor quality. Sugar acid ratio under red light, blue light and R+B light were significantly higher than that under the control,and it was the highest under R+B light. Red light improved the major aroma content and aldehydes content, and the content of alcohols was enhanced under blue light. The blue light can promote the content of esters formation to some extebt.