Photosynthetic Characteristic And Its Responses To The Environment Of Several Afforestation Tree Species

In this paper, using the LI-6400 portable photosynthesis system which made by LI-COR of American, in the natural environment indexes of the 5 afforestation tree species in area of Hohhot were measured,such as Syringa oblate,Loniseaniatrilob(Lindl.)Carr,P.alba L.var.pyramidalis Bge.,Robinnia pseudoscacia and Sophorajaponica.These indexes were photosynthesis rate,stomatal conduction,Ci, transpiration rate,photosynthetic available radiation and rapture.Furthermore, Light curve, ACI curve of 5 afforestation tree species were measured.The effect on photosynthetic rate of stomatal conduction,Ci, photosynthetic available radiation and rapture were analyzed.And transpiration rate, water use efficiency were studied.The classifying results showed:1. In the natural environment, the diurnal changes of photosynthesis rate always have two types. The curve of diurnal variation of Robinnia pseudoscacia,P.alba L. var. pyramidalis Bge. leaf photosynthesis showed one peak .But the curve of diurnal variation of Syringaoblata,Loniseaniatrilob(Lindl.)Carr,Sophorajaponica L.leaf photosynthesis showed two peaks.2. The daily average transpiration rate of the 5 trees in the order from high to low was: P.alba L. var. pyramidalis Bge(.1.911)ï¹¥Loniseaniatrilob(Lindl.)Carr(1.904)ï¹¥Syringa oblate(1.398)ï¹¥Robinnia pseudoscacia(0.911)ï¹¥Sophorajaponica(0.669).Suggesting that the first 3 tree species have relatively higher transpiration rate than others.They are high transpiration.The daily average water use efficiency of the 5 trees in the order from high to low was: Sophorajaponica(10.78)ï¹¥Robinnia pseudoscacia(5.54)ï¹¥Loniseaniatrilob(Lindl.)Carr(4.52)ï¹¥Syringa oblate(4.10)ï¹¥P.alba L. var. pyramidalis Bge.(3.61).Suggesting that the first 2 tree species have relatively higher water use efficiency than others.3. Sophorajaponica has high light saturation point, low light compensation point,it could adapt to wide extent of light.The CO2 compensation point of photo synthesis of the 5 trees in the order from high to low was: P.alba L. var. pyramidalis Bge.ï¹¥Syringa oblateï¹¥Loniseaniatrilob(Lindl.)Carrï¹¥Robinnia pseudoscaciaï¹¥Sophorajaponica.CE of the 5 trees in the order from high to low was:Robinnia pseudoscaciaï¹¥Sophorajaponicaï¹¥Syringa oblateï¹¥P.alba L. var. pyramidalis Bge.ï¹¥Loniseaniatrilob (Lindl.)Carr.Suggesting responses to the high CO2 concentration that Robinnia pseudoscacia and Sophorajaponica were the best apparent.Information and data presente here are helpful to choose tree species and guide the water management during the garden practices.