A Study of the Effects of Shading on the Growth and Development of Davidia involucrata Seedlings

In order to investigate the effects of shading on the growth and development of Davidia involucrata seedlings,a comparative study was made of the photosynthetic characteristics and growth characteristics of D. involucrata seedlings. The one-year old D. involucrata seedlings cultivated were used as experimental materials under different light intensity (100%,50% and 25%). The results showed that (1) the daily net photosynthetic rates of different shading treatments of D. involucrata seedlings were all bimodal curves and "Midday depression" phenomenon was observed. But under different light intensity the value and time of the peak were different. The daily variation trend of transpiration rate under different light intensity was different and in an order of one-layer shading (5%) > two-layer shading (25%) > full sunlight.. (2) The average leaf area,specific leaf area and leafstalk length of Davidia involucrate under shading were larger than those of Davidia involucrate under full sunlight. It indicated that Davidia involucrate had strong ability of utilizing the limited low light resource. This study showed that Davidia involucrata seedlings grew best under appropriate shading(50% Transmittance).