Effect Of Light Quality On Physiological Characteristics,Yield And Quality Of Chinese Cabbage In Spring

The requested characteristics for light qualities of Chinese cabbage(Brassica campestris L.ssp.Pekinensis,cv.?Jujin?)was studied,with LED light of different colors.The light quality were white: red light = 4:1(WR);white: blue light = 4:1(WB);white : green light = 4:1(WG);white: yellow light = 4:1(WY).White light(W)treatment was used as the control.On this basis,the effect of color films on the physiological characteristics,yield and quality of Chinese cabbage were investigated,with colorless plastic film as the control(CK).The main results are as follows:1.Light quality has great effect on the growth of Chinese cabbages.WR increased,while WG and WY decreased the leaf area and dry matter,compared with the control.WB treatment did not affect the leaf area and dry matter.WR and WB showed the highest specific leaf weight,and significantly greater than the control.However,No marked differences were observed in it between any other treatment and the control.The plant range of WR treatment plants was significantly larger than that of the control plants.Whereas,WY treatment plants revealed a markedly less plant range,compared with the control.Similar plant range were found in WB,WG and the control.2.WR increased the pigment content,photosynthetic rate(Pn),apparent quantum yield of carbon assimilation(AQY),carboxylation efficiency(CE),actual photochemical efficiency of PS ?(?PS ?),high temperature compensation point,and activities of ribulose bisphosphate carboxylic enzyme(RuBPCase),fructose bisphosphatase(FBPase),and transketolase(TK),whereas decreased the chlorophyll a/b and low temperature compensation point,compared with the control.No significance difference between WB and the control in Pn,AQY,CE,?PS?and the activity of photosynthetic enzymes.However,WY and WG led to a decrease in the pigment content,Pn,stomatal conductance(Gs),AQY,CE,activity of photosynthetic enzymes and high temperature compensation point,and an increase in the chlorophyll a/b and low temperature compensation point.These data suggested that increased the proportion of red light can improve the photosynthetic capacity,weak light use efficiency and tolerance to high and low temperature,to a certain degree.Some stomata would be closed if the proportion of yellow or green light increased,and as a consequence of reduced photosynthesis and tolerance to high and low temperature.3.The colored films decreased the transmission proportion of visible light(400~700nm),while increased near-red light and far-red light ratio.Red film increased the long wavelength light ratio,while blue film increased the short wavelength light ratio in the plastic greenhouse.Purple film led to a decrease in the ratio of short wavelength light,whereas no significantly change in the ratio of long wavelength light,compared with the control.On the contrary,green film decreased the ratio of long wavelength light,but no change in short wavelength light,compared with the control.4.At low temperature(late Feb.~ beginning of Mar.)and high temperature(late Apr.)condition,the malondialdehyde(MDA)content of Chinese cabbage of purple film treatment was the lowest,those of the red and blue film treatments were secondly,and that of green film treatment the highest among the four treatments.The purple film treatment plants showed higher contents of superoxide dismutase(SOD),peroxidase(POD),catalase(CAT),glutathione reducatase(GR)and ascorbate peroxidase(APX),as well as the contents of glutathione(GSH)and ascorbic acid(ASA),compared with the control.The activities of SOD,POD,GR and APX were also higher obviously than those of the control,but no significantly differences were found between the red film treatment and the control in CAT activity and contents of GSH and As A.The blue film treatment maintained higher levels in the activity of antioxidant enzymes and the contents of antioxidant substance at early stage.However,the blue film treatment plants revealed marked lower levels in the above parameters than the control plants at later stage.Green film treatment showed a significantly decrease in the activities of antioxidant enzymes and the contents of GSH and AsA compared with the control in the whole growth stage.5.Under the same photon flux density(PFD),purple film treatment showed the largest leaf area,biggest dry matter and highest specific leaf weight among the five treatments,and the biological yield and economic yield increase by 10.8% and 15.1% respectively,compared with the control.Purple film increased the contents of soluble sugar,Vc and free amino acid in Chinese cabbage,and made good quality in general.6.The purple film treatment plants revealed higher Pn,lower incidence and disease index of soft rot,larger growth,higher yield and better quality under 65 ~ 77% light transmittance.Therefore,it can be used as the dedicated film of Chinese cabbage in spring.