不同海拔梯度的滇杨对模拟增温和UV-B辐射增强的响应

Due to the greenhouse effect and ozone depletion, global warming and ultraviolet-B reaching the earth surface are predicted to increase in the future.As a result, plants will be directly or indirectly affected, especially trees. Of trees, poplar is a species that is both widely distributed and highly adaptable, therefore, its response to global climate change is the focus of research. In our original research, the response of poplar to enhanced UV-B is affected by drought and fertilizer, and Populus Kangdingensis, which originates from high alitutudes, has greater tolerance to enhanced UV-B radiation than P. cathyana originating from low altitudes. However, whether the response of populus species to enhanced UV-B radiation are affected global warming, and the response of a Populus species from different altitudes to enhanced UV-B radiation remain unclear. In order to address these questions, we select P. Yunnanensis from low to high altitudes as the experiment material. Through the experiment, we want to determine the effect of experimental warming, enhanced UV-B radiation and their combination on plant growth and physiological traits like photosynthesis and secondary metabolites. Then, the adaptation strategies of poplar to global warming, changes of light intensity and light quality will be fully discussed. Our research on poplar will provide scientific data to address ecological problems caused by global climate change and contribute to rehabilitation of degraded vegetation.

温室效应和臭氧层的破坏使得全球温度升高，到达地球表面的UV-B辐射增强，这将对植物，特别是树木，产生直接或间接的伤害。杨树是全世界分布最广、适应性最强的树种之一，其对全球气候变化的响应一直是关注点。在前期研究中，课题组发现杨树对UV-B辐射增强的响应受到干旱、肥料的影响，且高海拔的康定杨比低海拔的青杨具有更强的抗性，但增温是否影响杨树对UV-B辐射增强的响应、不同海拔梯度的同一种杨树对UV-B辐射增强和增温的响应规律仍不清楚。为此，本项目拟选用不同海拔梯度的滇杨作为试验材料，采用人工模拟增温和UV-B辐射增强的方法，研究植株生长发育中的形态变化、光合生产、次生代谢等生理生态响应及温度升高对植株抗UV-B辐射的影响，揭示杨树对气温升高、光强和光质变化的适应规律，为评价全球气候变化所引发的生态学效应提供基础数据，同时为植被恢复与重建提供理论指导。

以不同海拔梯度的滇杨(Populus yunnanensis)、川杨(P. szechuanica)为材料，研究了人工模拟增温和UV-B辐射增强对杨树生长的影响。研究结果表明，人工模拟增温1.79℃显著地提高了滇杨和川杨的叶绿素含量、净光合速率，对高海拔川杨的物候期影响较大，表现为芽萌发期提前，生长期延长，休眠期缩短；低海拔的滇杨则积累更多的ABA、脯氨酸，以增强对增温的耐性。UV-B辐射增强2.5和5.0 KJ /(m2•d)对供试杨树的芽数量、吲哚乙酸含量等没有明显影响，不过显著降低了滇杨的株高、节间长度、叶绿素a及总叶绿素含量，而川杨的株高和节间长度仅在5.0 KJ /(m2•d) UV-B辐射下才出现降低。与低海拔的滇杨相比，高海拔的川杨及滇杨种群可以通过增强POD活性、叶片厚度等方式降低UV-B 胁迫,因而对UV-B辐射增强表现出了耐性；当增温和UV-B辐射增强同时作用时，UV-B辐射对滇杨生长的影响大于增温，且二者之间存在一定的交互作用。在增温作用下，UV-B辐射对叶干重、根冠比的影响降低；增温使ABA的含量降低了48%，对IAA没有影响，相反，UV-B辐射显著地降低了IAA含量，提高ABA含量。还发现，太阳光中的UV-B波段有抑制杨树生长作用，特别是低海拔的杨树受到的影响较大；UV-A辐射则提高了叶面积、生物量等,有利于杨树植株生长。