Acclimatization of Midrib Angle and Petiole Angle of Camptotheca acuminate Decne to Different Light Regimes in Evergreen Broadleaves Forests

As a special deciduous broadleaf tree in evergreen broadleaves forests,Camptotheca acuminate is a class Ⅱ protected plant in China.In this paper,the light response and acclimation of leaf inclination in three different light regimes(open,gap and understory) was compared.The results indicated that significant difference among different regimes existed in ecological factors such as PAR,temperature,Vpd and etc.In different light regimes,the extents of diurnal change of midrib angle and petiole angle of Camptotheca acuminate were different,and the highest extent existed in open,the second was in forest gap,and the least was in understory.The midrib angle and the petiole angle appeared at "peak" at 16:00,14:00 and 12:00 respectively in these three light regimes in the sunny day in summer,correspondingly,the values of midrib angle were about 140°,128° and 112°,and the values of petiole angle were about 67°,59° and 55° respectively.In the sunny day,diurnal courses of midrib angle and petiole angle of Camptotheca acuminate showed a certain cooperative relationship to some extents in strong light regimes.In order to effectively avoid strong light or assimilate moderate PAR,seedlings of Camptotheca acuminate increased or cut down its midrib angle and petiole angle at the same time.These leaves movement was a kind of adaptive responses of Camptotheca acuminate to different light regimes.