小蓬竹光合作用特性对遮阴处理的响应

Effect of Shading Treatments on Photosynthesis of Drepanostachyum luodianense

以小蓬竹为试材,以自然光为对照,研究了轻度遮阴(LS,74.32%自然光)、中度遮阴(MS,44.83%自然光)、重度遮阴(SS,18.57%自然光)3种遮阴处理对小蓬竹的光合作用和光响应特征的影响,以探讨濒危植物小蓬竹对光照的适应性。结果表明:轻度遮阴下小蓬竹叶片光合速率(Pn)、最大净光合速率(Pnmax)、表观量子效率(AQE)以及光能利用效率(LUE)相对于对照(CK)有所提高,而光饱和点(LSP)、光补偿点(LCP)以及暗呼吸速率有所下降;中度及重度遮阴下小蓬竹叶片Pn等气体交换性指标,AQE、Pnmax、LSP、LCP以及暗呼吸速率(Rd)等光响应参数均随遮阴加重而逐渐下降,但LUE却极显著升高。说明小蓬竹对轻度遮阴环境有良好的适应性,适度遮阴更有利于其生长发育。遮阴加重的情况下,小蓬竹直接地提高LUE、降低LCP和LSP,维持一定光合作用水平并减少能量消耗,使其在光照不足条件下迅速实现碳的净积累,从而加强对弱光逆境的抵御能力。由此推断,小蓬竹对中度及重度遮阴环境具有较强的适应性。

Taking the seedlings of D.luodianense（Yi et R.S.Wang）Keng f.as materials,effects of three shading treatments of low shading（LS,the relative light intensity was 74.32%）,moderate shading（MS,the relative light intensity was 44.83%）and severe shading（SS,the relative light intensity was 18.57%）on the photosynthesis and the parameters of optical response characteristics of D.luodianense were studied by light control experiment,with natural light as the contrast（CK,the relative light intensity was 100%）,in order to investigate shade tolerance of endangered plant of D.luodianense.The results showed that,compared with CK,under LD net photosynthetic rate,maximum net photosynthetic rate,apparent quantum efficiency and light use efficiency（LUE）of D.luodianenseincreased a lot,while light saturation point（LSP）,light compensation point（LCP）and dark respiration rate declined.Under MD or SD,gas exchange parameters like net photosynthetic rate,apparent quantum efficiency,maximum net photosynthetic rate,light saturation point,light compensation point and dark respiration rate and the other light response parameters of D.luodianense were gradually decreased with the strengthening of shading stress,but LUE increased significantly.These results showed that D.luodianense could well adapt to low shading environment and moderate shading conditions were more advantageous to the growth and development.In the further aggravating shading environment,D.luodianensecould enhance directly LUE,LCP and LSP to maintain a certainlevel of photosynthesis and reduce energy consumption,so that the rapid accumulation of carbon could be realized and so as to strengthen the ability to resist.Therefore,D.luodianense had strong adaptability to moderate shading and severe shading environment.