不同起源时期的3种被子植物对酸雨胁迫响应的光合生理生态特征

 为了验证起源时间较长的植物具有较强适应性的假设, 人工模拟酸雨胁迫, 研究了在不同酸雨处理下不同起源时期的3种被子植物乐东拟单性木兰(Parakmeria lotungensi)、石栎(Lithocarpus glaber)和山核桃(Carya cathayensis)的光合生理适应特性。实验设置了酸雨对照处理(pH 5.6)、中度酸雨胁迫处理(pH 4.0)和重度酸雨胁迫处理(pH 2.5), 并测定了这3种植物的光合特性。研究结果显示: 1)在不同强度的酸雨处理下, 乐东拟单性木兰的光合能力大小趋势为pH 2.5 > pH 4.0 > pH 5.6, 石栎则为pH 5.6 > pH 4.0 > pH 2.5, 但山核桃在酸雨处理之间差异不显著; 2)在酸雨对照处理(pH 5.6)中, 石栎的光合能力相对较高, 其次是乐东拟单性木兰, 山核桃最小。但在重度和中度酸雨胁迫下(pH ≤ 4.0), 3种植物光合能力的大小趋势为乐东拟单性木兰 > 石栎 > 山核桃, 且酸雨胁迫越严重, 上述趋势越明显。研究结果表明: 在重度酸雨胁迫下, 起源时间较早的乐东拟单性木兰表现出较高的光合与适应能力。从应用的角度出发, 建议考虑将乐东拟单性木兰作为酸雨灾害严重地区植被构建的物种之一。

PHOTOSYNTHETIC AND PHYSIOLOGICAL CHARACTERISTICS OF THREE ANGIOSPERMS OF DIFFERENT EVOLUTIONARY AGES UNDER ACID RAIN STRESS

Aims Our aims were to reveal the effects of acid rain stress on photosynthesis of three angiosperms (Parakmeria lotungensi, Lithocarpus glaber and Carya cathayensis) of different evolutionary ages, test the hypothesis that species with longer evolutionary time have higher adaptability and interpret results in terms of vegetation reconstruction in regions with severe acid rain. Methods Three simulated acid rain treatments were randomly applied to the species: severe acid rain (pH 2.5), moderate acid rain (pH 4.0) and control (pH 5.6). The light response curves were determined in April 2007. Important findings Under different acid rain treatments, maximum net photosynthetic rate (P_nmax) of P. lotungensi was in the order of pH 2.5 > pH 4.0 > pH 5.6, while that of L. glaber was pH 5.6 > pH 4.0 > pH 2.5 and there were no significant differences for C. cathayensis. In the control, the order of P_nmax was L. glaber > P. lotungensi > C. cathayensis. However, in the treatments with pH ≤ 4.0, the order was P. lotungensi > L. glaber > C. cathayensis. Therefore, P. lotungensi has higher photosynthetic capacity and higher adaptability than the other two species under acid rain stress. Compared with the other two species, P. lotungensi is a more favorable species for vegetation reconstruction in regions with severe acid rain.