模拟酸雨对盆栽马尾松叶片光合特性的影响

Effect of Simulated Acid Rain on Photosynthetic Characteristics of Potted Pinus massoniana

采用LI-6400XT便携式光合测定仪,对缙云山马尾松在不同强度酸雨(pH 5.6,pH 5.0,pH 4.0,pH3.5,pH 3.0,pH 2.5和pH 2.0)下的光合特性进行测定。结果表明:pH 3.5～5.6的酸雨处理条件下,净光合速率、蒸腾速率和气孔导度受酸雨影响不明显,从pH 3.0或pH 2.5开始出现明显的降低趋势,且pH2.0出现不同于前几种处理的日变化趋势;从水分利用效率分析,酸雨胁迫对其影响不明显;pH 4.0～5.6的酸雨处理条件下,最大净光合速率、光饱和点和光补偿点变化不明显,从pH 3.5开始出现显著降低的趋势,且在pH 2.0时受酸雨影响已经非常明显,无法模拟出最大净光合速率、光饱和点和光补偿点;总体分析,酸雨对马尾松叶片光合特性的影响临界范围为pH 3.5～4.0,酸雨对马尾松幼苗致命的影响临界范围为pH 2.0～2.5。

Under different intensities of acid rainfall, i.e. pH 5.6, pH 5.0, pH 4.0, pH 3.5, pH 3.0, pH 2.5, pH 2.0, the photosynthetic characteristics of potted Pinus rnassoniana, located in Jinyun mountain, were measured by the LI-6400XT portable photosynthetic meter. Results showed the net photosynthetic rate, the transpiration rate and the stomata conductance were slightly affected by the acid rain ranged from pH 3.5 to pH 5.6, while decreased rapidly when pH values was 2.5 or 3.0. In particular, the above three properties started to exhibit inverse daily tendency when the pH was as low as 2.0. On the contrary, water use efficiency was scarcely influenced by acid rain stress. Meanwhile, the maximum net photosynthetic rate, the light saturation point and the light composition point held almost constant values under the acid condition of pH 4.0 to pH 5.6, but started to decline dramatically when the pH reduced 3.5, even more, they could not be simulated when the pH reached 2.0. Overall, the critical range that the acid rain played an important role on potted Pinus massoniana was between pH 3.5 and pH 4.0, and the mortal range for seedlings was from pH 2.0 to pH 2.5.