| As one of the important multi-purpose ornamental trees, Yulania has been widely cultivated in both traditional and modern landscaping. However, species differences in photosynthetic characteristics have a great impact on their regional adaptation and distribution. In this dissertation, a comparative study on the photosynthetic characteristics of seven species(cultivator) of Yulania, i.e. Yulania denudata, Y. liliiflora, Y.*soulangeana, Y. wugangensis, Y. pyriformis, Y. campbellii’hanlian’, Y. axilliflora was carried out by using Li-6400 photosynthetic instrument in the field condition. The results indicated that in general, the trend for the net photosynthetic rate of the leaves of seven species(cultivator) first rose up and then became steady as their growth. The variation tendency of net photosynthetic rate, stomatal conductance and transpiration rate of all species tested did not show significant difference. The change of net photosynthetic rate and transpiration rate tends to be highly consistent in Y. pyriformis, while change of transpiration rate and stomatal conductance tends to be highly consistent in Y. x soulangeana. A double-apex curve was seen in the diurnal variation of the net photosynthetic rate of Y. campbellii ’hanlian’, suggesting an obvious’midday depression’phenomenon occurred in this plant. Its Stomatal conductance and Transpiration rate were positively correlated with net photosynthetic rate. Water use efficiency (WUE) of four typical Yulania cultivated in northern China, i.e. Y. wugangensis, Y. pyriformis, Y. campbellii’hanlian’, Y. axilliflora were lower than Y. denudata, Y. liliiflora, and Y. ×soulangeana those derived from South of China. The planting of these seven species(cultivator) of Yulania in accordance with their photosynthetic characteristics would broaden application prospects but also market value in Hangzhou area. |
