| Light is an important environmental factor for plant growth.Light quality and light intensity can directly affect the growth development and morphogenesis of plant.The thesis mainly taking P.nagi.seedlings as the research object,on the condition of light qualities of white,red,blue and different kinds of red and blue light intensities of 30 μmol·m-2·s-1,60μmol·m-2·s-1,90μmol·m-2·s-1 and 120 μmol·m-2·s-1,studied and analyzed the influence of the growth,metabolic product and photosynthetic characteristics.The growth indexes included survival rate,height,ground diameter,branches’ number,root,leaf characteristic values,biomass and biomass ratio.Metabolite included primary metabolites(soluble sugar,starch,soluble protein,free amino acid,nitric nitrogen)and secondary metabolites(flavonoid,ganodera).Photosynthesis included photosynthetic parameter(net photosynthetic rate,transpiration rate,stomatal conductance,intercellular CO2 concentration),chlorophyll fluorescence parameters(Fo,Fm,Fv/Fm,Y(Ⅱ),qp,NPQ)and photosynthetic pigments(chlorophyll a,chlorophyll b,chlorophyll a/b,chlorophyll,carotenoid).So that we could discover the response mechanism to growth and photosynthesis of P.nagi.in different light quality and light intensity.The thesis laid a foundation for the light biological theory of P.nagi..It could also provide the basis for the use of LED in breeding and seedling nursing with equipment as a new kind of energy-saving light.The thesis mainly drew the following conclusions.(1)Red LED was good for the growth of P.nagi..The P.nagi.which was cultivated in red LED had the biggest dry weight,ground diameter and height.And the three indexes in red LED were respectively bigger by 89.13%,326.67%and 86.23%than those in white LED.The DW/FW and R/C were respectively 6.45%and 73.33%than those in blue LED.In different light quality and light intensity,the transplanting seedling’s survival rate in 60 μmol·m-2·s-1 red LED was the highest of all,by 96.33%.In 60 μmol·m-2·s-1 red LED,the ground diameter,height and new leaves’ number were biggest.They were 0.64 mm,5.14 cm and 8.46 pcs.In 90 μmol·m-2·s-1 blue LED,P.nagi.had the biggest total root length,total root surface area,root number and root branch number.They were 122.82 cm,25.22 cm2,464.50 pcs and 1507.50 pcs.(2)Enhancing the intensity of red LED and blue LED could improve the the accumulation of metabolite,90 μmol·m-2·s-1 and 120 μmol·m-2·s-1 red and blue LED could accumulate more carbon and nitrogen metabolites in early transplanting.The study also showed that,the P.nagi.had the regulating ability to adapt weak light.Therefore,the light environment adaptability of P.nagi.changed and could accumulate more carbon and nitrogen metabolites under other light environment cultivation in the middle and later periods of the test.Red LED was good for the accumulation of flavones and triterpene of P.nagi..The content of flavones and triterpene were 206.60%and 23.88%higher than blue LED.(3)Cultivated in different light qualities,the ability of accumulating carbon and nitrogen metabolites of P.nagi.which was cultivated in red LED was weakest.The contents of soluble sugar and starch in blue LED were 15.70%and 113.77%higher than those in red LED.The contents of soluble protein and free amino acid were 191.49%and 120.75%than those in red LED.But there was no significant difference of dry matter in the cultivation of white,red and blue LED.(4)Light environment regulation had great influence on the photosynthesis of P.nagi..Light quality and light intensity had positive correlation with the net photosynthetic rate of P.nagi..The correlation were 0.891,0.909 and 0.971 in light quality,red intensity and blue intensity.The diurnal change of photosynthetic rate of P.nagi.cultivated in red and white LED were unimodal curve and had not obvious midday depression phenomenon.Correlation analysis showed that midday depression phenomenon happened maily because of the change of leaf temperature,air pressure.And the inside index was non-stomatal limitation.Related research considered that the diurnal change of unimodal curve could improve the biological yield of P.nagi..P.nagi.cultivated in red LED had better height,ground diameter,and so on.In different light intensity,P.nagi.cultivated in the intensity of 120 μmol·m-2·s-1 red and blue LED had the greatest net photosynthetic rate.The diurnal change of net photosynthetic rate of P.nagi changed unimodal curve to bimodal curve with the increasing of light intensity which was cultivated in red LED.(5)Light quality and light intensity had some correlations with the chlorophyll fluorescence parameters of P.nagi..The correlation index between light quality and Fv/Fm was-0.866.The correlation index of red intensity among Fv/Fm,Y(Ⅱ)and qp were-0.713,0.675 and 0.790.The correlation index of blue intensity among Fv/Fm and NPQ were-0.845 and 0.833.There was no photoinhibition to P.nagi.in different light environment.The Y(Ⅱ),qp and NPQ had no significant differences in the cultivation of white,red and blue LED.Compared with red LED,the Fo of P.nagi.cultivated in white LED was 11.90%higher than that of P.nagi.cultivated in red LED.P.nagi.cultivated in white LED protect PSII reaction center through the increasing of Fo.Besides,the contents of chlorophyll and carotenoid were 19.34%and 25.00%higher than those in red LED.The increasing of Fo showed that,the PSII reaction center was destructed and the net photosynthetic rate was reduced.There was no significant difference of chlorophyll fluorescence parameters in different light intensity.60 μmol·m-2·s-1 red LED had lowest Y(Ⅱ),qp,NPQ and resulted in the minimum net photosynthetic rate.The Fm,Fv/Fm,Y(II)cultivated in 120 μmol·m-2·s-1 blue LED were reduced.But the NPQ was maximum.P.nagi.mainly protect photosynthetic system through heat dissipation in order to remit midday depression phenomenon.(6)The photosynthetic pigment content of P.nagi.had significant difference in different light environment regulation.P.nagi.reflected different environmental adaptability.Chlorophyll content was white LED>red LED>blue LED.Comparing the photosynthetic pigment content of red and bule LED showed that,red LED was good for the formation of chlorophyll b while blue LED was good for the formation of chlorophyll a.The chlorophyll a/b was 2 and least than others.P.nagi.cultivated in red LED had more strong ability to adapt to the weak light than others.Red LED also had significant positive correlation with net photosynthetic rate.The carotene content of P.nagi.cultivated in red LED was 0.20 mg·g-1 and lower 20%than that in white and blue LED.90 μmol·m-2·s-1 light intensity had the highest carotinoid content in the early transplanting.At the end of cultivation,the chlorophyll a/b and carotinoid content were the highest in the intensity of 120μmol·m-2·s-1. |
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