Effects Of Different Light Quality On Mineral Elements And Photosynthesis Of Blueberry Seedlings

With the rapid development of the blueberry(Vaccinium spp.)industry,the market is increasingly concerned about the quality of blueberry seedlings and the multipurpose cultivation of blueberries.Light significantly affects seedling growth and development,photosynthesis and other aspects.In this study,Light Emitting Diodes(LEDs)were used as the light source,and four treatments of red-blue(3R1B),red-blue-green(3R1B+G),white light(W),and greenhouse regular light(CK)were set up.The blueberry seedlings of ’莱格西’(Legacy)were used as experimental materials.The effects of light quality on the growth and development of blueberry seedlings,the absorption and distribution of mineral nutrients,and the characteristics of light energy utilization were systematically analyzed.The aim was to clarify the effects of different light quality on mineral elements and photosynthesis of blueberry seedlings.To lay the foundation for the establishment of effective nursery support management technology under different light quality.The main findings are as follows:1.The red-blue and red-blue-green light qualities can significantly promote the growth of blueberry seedlings(P<0.05).The red-blue-green light biomass(5.33±0.30 g/plant)increased by 87%compared with the control.The content of carotenoids in leaves of blueberry seedlings under red-blue and white light increased by 30%and 20%,respectively,but significantly reduced the content of chlorophyll(Chl.a+b)in seedlings,which decreased by 60%and 30%respectively.2.The red-blue and red-blue-green light qualities significantly promoted the accumulation of various mineral elements in the ground part of blueberry seedlings(P<0.05),but reduced the content of various mineral elements.Among them,red-blue-green significantly increased the accumulation of macro elements(Ca,Mg,and Na),and they all increased by more than 60%compared with CK.There was a significant difference in Mn element content between red-blue and red-blue-green treatments(P<0.05),and red-blue-green was 50%lower than CK3.The red-blue and red-blue-green light quality changed the distribution of mineral elements in different organs of blueberry seedlings.The red-blue increased the distribution ratio of N,Na and Zn in leaves and increased the distribution ratio of other elements in stems or roots.There was a significant positive correlation between macro elements(Ca,Mg,and Na)and blueberry seedling biomass(r=0.979,0.909,0.986,respectively)4.The red-blue light quality significantly increased the net photosynthetic rate(Pn),stomatal conductance(Gs)and transpiration rate(Tr)of blueberry seedling leaves.The maximum Pn of blueberry seedlings under red-blue was(6.37±0.27 μmol CO2 m-2 s-1);In the diurnal change,the red-blue mass mainly increased the afternoon Pn,Gs and Tr,but decreased the intercellular CO2 concentration(Ci),indicating that the change of the net photosynthetic rate of blueberry seedlings is mainly limited by the stomatal factor.5.The red-blue light quality enhanced the non-photochemical quenching coefficient(NPQ)of blueberry seedling leaves,reduced the potential photochemical efficiency of chlorophyll(Fv/Fm),the actual photochemical efficiency(ΦPSII),and the photochemical fluorescence quenching coefficient(gP);There was a significant positive correlation between Fv/Fm,ΦPSⅡ,qP and chlorophyll(r=0.934,0.902,0.816),and there was a significant positive correlation between NPQ and plant height of blueberry seedlings(0.826)(P 0.05)6.The red-blue light quality reduced the content of mineral elements and chlorophyll in the leaves of blueberry seedlings,indicating that there is a certain relationship between the two under light quality,which can affect the absorption and distribution of mineral elements through photosynthesis.