The Comparative Research Of Photosynthetic Rate In Three Magnoliaceae Species

Magnolia liliflora Desy, Magnolia denudata Desy and Magnolia grandiflora belongto magnoliceae species, which widely distributing in Enshi autonomous prefecture. Theyare ornamental plants for landscape. We analyzed the photosynthetic rate of the threespecies, to make people know them characteristic of biology and provide the theory basisfor the cultivation. This study is of guiding significance in finding out the adaptabilities ofthree Magnoliaceae species and landscape arrangements oPhotosynthetic characteristics of Magnolia liliflora Desy, Magnolia denudata Desyand Magnolia grandiflora were recorded by TPS1 portable photosynthesis system in afine day and somber day. Effects of physiological and zoological factors such as containsphotosynthetic affecting radioation, temperature, air CO₂ concentration, stomatalconductance and transpiration were measured.The results were briefly summarized as follows:(1) The net photosynthetic rate (Pn) of the three Magnoliaceae species is affected bythe light, temperature, water, concentration of carbon dioxide, and so on.(2) Comparative research on net photosynthetic rate (Pn) of the three Magnoliaceaespecies was processed in a fine day and somber day. Response curves in a fine day took ontwo-peak pattern, the first peak reached at 10:00, and the second at 16:00, and obvious"noon break" phenomenon was presented. In a somber day diurnal variation of Pnpresented one-peak pattern, the peak reached at 14:00.(3) The diurnal change curves of transpiration rate are similar with photosyntheticrate which took on two-peak pattern in fine day.(4) The stomata conductances of the three Magnoliaceae species are positivelycorrelated with the photosynthetic rate. And they are evidently decided by thetranspiration rate.(5) The Pn of leaves are difference among these different species of Magnoliaceae.The average photosynthetic rate and growth of Magnolia grand flora is higher than theothers in fine day. Magnolia grand flora and Magnolia leilira grow better than that(Magnolia denudate Desr) in somber day.