Effects Of LED Light Environment On Nutritional Quality And Physiological Basis Of Toona Sinensis Sprouts

Toona sinensis sprouts have the characteristics of being free from seasonal restrictions,short growth cycle,fresh and tender taste and rich flavor.Achieving high quality and high yield of horticultural products through precise regulation of LED(light emitting diode)light environment has become a current research focus.This topic first analyzed and compared T.sinensis sprouts with T.sinensis buds,clarified the nutritional value of T.sinensis sprouts.Based on this,the effects of LED light qualities and intensities on growth and development,nutritional quality,and volatile components of T.sinensis sprouts were emphatically studied,and also studied its physiological basis.Finally,the application of LED light in the postharvest and preservation of T.sinensis sprouts was studied.The main research results were as followed:1.The nitrate content in T.sinensis buds was as high as 3143 mg/kg,which was 7 times that of T.sinensis sprouts.Comparative analysis of volatile components showed that the contents of five sulfur compounds in T.sinensis sprouts was higher than that in buds.The contents of AsA(ascorbic acid),calcium,and magnesium in T.sinensis sprouts were 63.1%,78.8%,and 103.9%higher than those in buds,respectively,and the FAA(free amino acids)contents were 3.5 times that in buds.The NQS(nutritional quality score)value of T.sinensis sprouts was 17.2 times that of buds,the nutritional value was much higher than that of buds.2.Compared with WL(LED white light),RL(LED red light)effectively promoted the elongation of hypocotyls,and the plant height of T.sinensis sprouts were increased by 59.8%.In the BL(LED blue light)treatment group,the contents of TP(total phenols)and TF(total flavonoids)were the highest,the antioxidant capacities enhanced significantly,and the content of AsA increased by 75.1%compared to WL.In group 3R1B(red and blue light ratio was 3:1),the sulfur compounds contents were the highest,and the contents of sucrose,water-soluble sugar,and total nitrogen increased significantly.The FAA contents in the treatment group with 5R1B(red and blue light ratio was 5:1)was the highest.3.Light intensity had no significant effects on the fresh weight of T.sinensis sprouts,while light intensity was 100 μmol·m-2·s-1 or 150μmol·m-2·s-1,the dry weight of two varieties of T.sinensis sprouts increased by 83.3%and 79.5%compared to those without light,respectively.Increasing light intensity had the most significant effect on improving the soluble sugar contents of two varieties of T.sinensis sprouts,compared to 50 μmol·m-2·s-1,it increased by 1.9 times and 1.1 times,respectively.With the increase of light intensity,the nitrate content also increased.There was no significant difference in soluble protein content between light treatments with different intensities.4.Compared with WL,the chlorophyll content in RL treatment group decreased by 24.3%,there was significant light stress with Fv/Fm<0.80,and the arrangement of palisade tissue were sparsely.There was no significant difference in chlorophyll content between BL and WL treatment group,and the leaf palisade tissue was closely arranged.Compared with.WL,the activities of antioxidant enzymes POD,SOD,and CAT in T.sinensis sprouts treated with BL increased by 27.2%,41.2%,and 14.4%,respectively.The activity of carbon and nitrogen metabolism enzymes in the 3R1B treatment group were significantly higher than that in monochromatic light treatment group.5.The weight loss rate of T.sinensis sprouts in the LED light treatment group was significantly higher than that in the no-light treatment group.Compared with different light treatments,the weight loss rate of the 3R1B treatment group was significantly lower than that of the WL on the third day.On the third day,the AsA and anthocyanin contents in the RL treatment group decreased least,and there was no significant difference in antioxidant capacity between the RL treatment group and the WL treatment group.RL can effectively inhibit the proliferation of microorganisms.On the third day,the total number of microbial colonies in the group was 23.3%lower than that in the BL group.In summary,the nutritional value of T.sinensis sprouts was much higher than that of buds,the nitrate content was lower,and the characteristic flavor was stronger.RL significantly increased the fresh weight of T.sinensis sprouts,BL significantly increased its antioxidant content and antioxidant capacities,and 3R1B combined light increased the content of sulfur compounds.The light intensity test results show that 100μmol·m-2·s-1 was the optimal light intensity for T.sinensis sprouts.The application of RL in post harvest preservation of T.sinensis sprouts was effective.