Influence of Growth Light Intensity on Photosynthetic Characteristics in Six Varieties of Hevea brasiliensis Seedlings

Six varieties of Hevea brasiliensis seedlings adapted for 1 year were grown under different light intensity,such as 100%,50%,25% and 5% nature light,the response characteristics of leaf photosynthetic system to light intensity and CO 2 concentration were studied.The results showed that sixH.brasiliensis varieties showed strong adaptability to different light environments.Under different light intensities,the maximum photosynthetic rate(P max),light compensation point(LCP),dark respiration rate(Rd),triose phosphate utilization rate(TPU),maximum carboxylation rate(V cmax) and maximum electron transport rate(J max) and chlorophyll content(Chl) showed significant differences(P 0.05),and did not light saturation point(LSP) and AQY(apparent quantum efficiency).Under the same light intensity,leaf maximum photosynthetic rate(P max),dark respiration rate(Rd),triose phosphate utilization rate(TPU),the largest electron transfer rate(J max) and chlorophyll content(Chl) among six varieties had significant difference(P 0.05),and did not light compensation point(LCP),maximum carboxylation rate(V cmax) and apparent quantum efficiency(AQY).Comprehensive comparison of parameters in six H.brasiliensis varieties,RRIM600,Yunyan77-4 and PR107 are fit for planting environment with relative light intensity of 100%-50%,while Yunyan77-2,GT1 and Reyan523 are suitable for that of 50%-25%.