Effect of Different Light Intensities on Photosynthetic Characteristics of Rhododendron 'Furnivall's Daughter'
WANG Song1,CAI Yan-fei2,3,LI Zhi-lin1,LI Shi-feng2,3(1 College of Horticulture and Landscape,Yunnan Agricultural University,Kunming 650201,China;2 Flower Research Institute,Yunnan Academy of Agricultural Sciences,Kunming 650205,China;3 Key Laboratory of Yunnan Flower Breeding,Kunming 650205,China)
To study the photosynthetic characteristics and physiological characteristics under different light intensities,to know the response of the light intensity and adaptive mechanism of Rhododendron 'Furnivall's Daughter',we potted 3 years old Rhododendron 'Furnivall's Daughter' under four different light intensity levels:100% of full sunlight(L1),53% of full sunlight(L2),30% of full sunlight(L3) and 17% of full sunlight(L4),which were controlled by sunshade screen.The result showed that:(1)Compared with the plant growing in full sunlight,appropriate shade can effectively improve the light saturation point(LSP),decreased the light compensation point(LCP) and respiration rate in the dark(Rd),thus the shaded plants had strongernet photosynthetic rate(Pn).Under the three light intensity treatments,LCP and Rd were the lowest;LSP and light-saturated photosynthesis at ambient CO2 concentration(Pmax) were the highest in 30% of full light.L3 was showed Rhododendron 'Furnivall's Daughter' the most appropriate growth light intensity.(2)With the reduction of light intensity,chlorophyll a was dropped slightly.However,the content of chlorophyll b,nitrogen in per unit area(LNCa) and photosynthetic nitrogen utilization efficiency(PNUE) were increased significantly.The influence of light intensity to chlorophyll b was more sensitive than that of chlorophyll a.As the results,total chlorophyll increasd obviously and the ratio of chlorophyll a/b decreased.(3)The plasticity analysis showed that Rhododendron 'Furnivall's Daughter' adapted to the changes of light environment mainly through the changes of Pmax,LSP,LCP,Rd,PNUE and total chlorophyll.However,leaf mass per unit area(LMA),LNCa,malondialdehyde(MDA) and superoxide dismutase(SOD) had little contribution.