Study And Application For Mechanisms Of Effects On Red And Blue Light Qualities On Carbon And Nitrogen Metabolism And Fruit Quality In Tomato

The light environment plays an important role in plant growth,and the plants receive different light qualities through the light receptors,which regulates the growth,development,photosynthesis and material metabolism of plants.As a new type of energy-saving light source,LED can accurately control the emission spectrum according to the needs of plants.It has been proved that red and blue light qualities have great effects on plant growth and development.It is necessary to carry out the research on the growth and development of crops under red and blue light.In this paper,the red and blue LED light sources were used and the effects of these light qualities on the growth and development,carbon and nitrogen metabolism and fruit qualities of tomato were studied.Furthermore,the effects of films added different light conversion?modulating?materials on the growth,development,fruit yield and quality of tomato in solar greenhouse were studied.The main results are as follows:1.The red?R?and blue?B?monochromatic light and different proportions of R and B light were used to treat tomato seedlings,and white light?W?was used as control.The results showed that there were significant differences in growth of tomato seedlings under treatments of different proportions of R and B light.The plant height,specific leaf area and intercellular CO₂ concentration of tomato seedlings was significantly promoted by R light,while the F_v/F_m and?PSII was decreased,the root growth was inhibited as the root activity declined,so that the seedling index was reduced.The seedling growth was significantly suppressed under B light and the chlorophyll content was decreased,while the chlorophyll a/b was enhanced.Furthermore,combination of R and B light was beneficial to the growth and development of tomato seedlings,and the plant dry mass,chlorophyll content and photosynthetic performance were significantly increased under 3R1B,respectively.The value of root activity under 3R1B treatment was increased by 34.2%compared with white light.In addition,seedlings grew strongly and had the highest value of seedling index under this treatment.2.The content of main nitrogenous substances,activities and gene expression of key enzymes from nitrogen metabolism in leaves of tomato seedlings were determined by setting R and B light and combination of R and B light and combination light of 3R1B,W light as control.The results showed that the nitrate nitrogen content and activities of nitrate reductase?NR?and glutamate dehydrogenase?GDH?and gene expression levels of six key enzymes for nitrogen metabolism under treatment of3R1B were significantly higher than those of other treatments and control,and the soluble protein content was also higher under this treatment than that of R and W.While no significant difference was found between this treatment and B light.In addition,the content of ammonium nitrogen and free amino acids under B light was significantly increased compared with those of other treatments and control,and activities of NR,nitrite reductase?NiR?,glutamine synthetase?GS?and glutamate synthase?GOGAT?,as well as relative expression of NR,NiR,GS2,FdGOGAT and LEAS1 were significantly higher than those of control.Comparing with W light,R light significantly reduced the total nitrogen content,and activities of NiR,GOGAT,GDH and asparagine synthetase?AS?and expression of GDH1 were inhibited as well.It is evidently that the combination of R and B light with appropriate proportion could promote the nitrogen assimilation and the absorption of transformed nitrogen in tomato seedlings,accelerating substances accumulation,and then,stimulating the growth of tomato seedlings.3.Compared with other treatments and control,the total carbohydrate and sucrose contents of leaves were significantly increased under 3R1B treatment,and the starch content was 39.1%higher than that of W light.The activities of acid invertase?AI?and neutral invertase?NI?were significantly decreased by 13.4%and 9.6%relative to control,respectively.Activities of sucrose phosphate synthase?SPS?and sucrose synthase?SS?in tomato leaves were enhanced under this treatment,and the trend of sucrose metabolism related gene expression was consistent with the enzyme activities.Compared with other treatments and control,the contents of total sugar,glucose,sucrose and starch in leaves were significantly decreased under B light,and the content of fructose was significantly increased.From the beginning of the color conversion period,the activities of NI,AI and SS were enhanced by B light,which indicated that this treatment was beneficial to the synthesis of fruit fructose.R and 3R1B light significantly increased the contents of glucose,sucrose and starch,and increased the activities of AI and NI,lower SS activity,but the former was not conducive to fructose and glucose accumulation,indicating that 3R1B treatment was more conducive to promote carbon metabolism of tomato.4.Compared with W light,R and 3R1B treatment could significantly increase the soluble sugar content?SSC?and sugar and acid ratio of tomato fruit,and decreased the content of titratable acid?TA?.The contents of vitamin C?Vc?,soluble protein and TA were significantly increased by B light,the content of SSC was lower,but the difference was not obvious with the control.With the fruit maturity,the content of lycopene and expression of geranylgeranyl pyrophosphate synthase?GGPS?and phytoene synthase?PSY?were significantly higher under R and 3R1B than those of B and control,especially for3R1B treatment.B light significantly reduced lycopene content,GGPS and PSY1 expression was inhibited under this treatment.It indicated that the combination of R and B light with appropriate proportion was conducive to turn color for tomato fruit,and to improve fruit quality.5.The light transmittance and heat retaining property of coated films and inner-added films both adding light conversion?modulating?agent and their effects on the growth,quality and yield of tomato were studied.It was found that the light transmittance and heat retaining property of the coated?PO?light conversion?modulating?films were improved compared with those of t inner-added anti-fog films,and the growth and yield per 667 m² of tomato were improved.Moreover,the maturity stage and fruit quality of tomato were greatly influenced by covering films added different kinds of light conversion?modulating?agent.The results showed that the yield per 667 m² was significantly higher under coated?PO?light-conversion?modulating?film of No.35.The increment was to 59.52%and 20.22%comparing with the inner-added and coated films without light conversion?modulating?agent.The fruit turning color period was advanced 2³ d under this film,and the lycopene content and the ratio of sugar to acid were significantly increased.Meanwhile,lycopene content and acid-sugar ratio in fruit were significantly improved as well.Overall,the addition of light conversion?modulating?agent coated with anti-fog film was more conducive to improve the comprehensive quality of tomato fruit.