| Syringa is one of the main garden trees in North China,with unique ornamental value and has very important status in the botanical garden afforestation construction,in this article;systematically study and comparison on photosynthetic characteristics were conducted of different species of Syringa,reveales basic eco-physiological characteristics and rules of photosynthesis and provides scientific plant for Syringa.In this paper,study on photosynthetic characteristics of Syringa oblata var.alba,Syringa reticulata var.mandshurica,Syringa velutina,Syringa vulgaris cv.'zi hong',Syringa oblata,Syringa villosa by using Li-6400 portable photosynthetic system.The results showed.1.The diurnal variation of net photosynthetic rate of S.oblata var.alba,S.reticulata var. mandshurica,S.vulgaris cv.'zi hong',S.oblate,S.villosa,S.velutina all presented "a single-peak" curve which showed no obvious midday depression.The seasonal variation of net photosynthetic rate showed almost alike tendency of this six species of Syringa,the net photosynthetic rate changed larger monthly:in July and August is the highest,in September and November is the lowest,June in between.2.In the determination of the entire growing season,the order of the sum of daily biomass accumulation of the six different species of Syringa from high to low is as followers:S.villosa, S.vulgaris cv.'zi hong',S.oblate,S.oblata var.alba,S.reticulate var.mandshurica,S.velutina.3.Based on the analysis of the light response curves,the order of photosynthetic capacity of the six different species of Syringa from high to low is:S.vulgaris cv.'zi hong',S.villosa,S. oblate,S.oblate var.alba,S.reticulata var.mandshurica,S.velutina.4.Seasonal variation of transpiration and photosynthetic rate are almost alike tendency of the six different species of Syringa,the order of the average transpiration rate from June to October is:S.villosa,S.oblate,S.vulgaris cv.'zi hong',S.reticulata var.mandshurica,S.oblata var.alba,S.velutina.5.The daily variation of water use efficiency of the six different species of Syringa shows Consistent tendency."A double peak" curve,the order of the mean of water use efficiency from high to low is:S.vulgaris cv.'zi hong',S.oblata,Syringa oblata var.alba,Syringa velutina,Syringa villosa,Syringa reticulata var.mandshurica,The water use efficiency in July and August is the highest,followed by June,September and October is the lowest. |
