模拟氮沉降对油松幼苗光合特性的影响

Effect of simulated nitrogen deposition on photosynthetic characteristics of Chinese Pine (Pinus tabulaeformis Carr.) seedings

以3年生油松幼苗为研究对象,设置了空白对照以及4个施氮处理:低氮(N1,15 kg/hm2·年)、中氮(N2,25 kg/hm2·年)、高氮(N3,50 kg/hm2·年)、过饱和氮(N4,150 kg/hm2·年),在生长季的中期和后期分别测定了不同处理下油松幼苗当年生针叶和1年生针叶的光响应曲线,通过最大净光合速率(Pmax)、表观量子速率(AQY)、呼吸速率(Rd)、光补偿点(LCP)、光饱和点(LSP)等光合响应曲线参数在不同处理之间的差异,探讨油松幼苗对氮沉降增加的适应性。结果表明:生长季中期,当年生针叶的所有光合响应曲线参数均没有受到氮处理的显著影响,而过饱和氮处理显著促进了1年生针叶的Rd,低、中、高氮处理增加了1年生针叶的LCP。生长季末期,当年生针叶和1年生针叶的Rd和LCP受到了过饱和氮处理的显著促进作用,其他光合响应曲线参数在各处理间均无显著差异。

To better understand the response of the photosynthetic characteristics of Chinese Pine （Pinus tabulaeformis Carr） to elevated nitrogen deposition, we set up a simulated nitrogen deposition experiment in Taiyue Mountiain, Shanxi. In this experiment, five treatments were designed, including control （CK）, Low N （N1, 15 kg/hm^2·a）, Medium N（N2, 25 kg/hm^2· a）, High N（Na, 50 kg/hm^2· a） and Supersaturated N （N4, 150 kg/hm^2·a）. The photosynthetic response curves of current-year and one-year conifer needles under different treatments were measured in the mid and late growing seasons. The maximum net photosynthetic rate （Pmax）, apparent quantum yield （AQY）, respiratory rate （Ra）, light compensation point （LCP） and light saturation point （LSP） among different treatments were measured to evaluate the adaptability of Chinese Pine seedlings to the increase of nitrogen deposition. The results showed that in the mid-growing season, all parameters of photosynthetic response curve in current-year needles were not significantly affected by nitrogen treatments, but the Rd of one-year needles was significantly higher under supersaturated nitrogen treatment. The LCP of one-year needles increased under low, medium and high nitrogen treatments. In the late-growing season, Rd and LCP of current-year needles and one-year needles promoted significantly under supersaturated nitrogen treatment, while other parameters of photosynthetic response curve were not significantly different among treatments.