套种于不同树龄橡胶林下谢君魔芋(Amorphophallus xiei)的光合特性研究

Photosynthetic Characteristics of Amorphophallus xiei Intercropped to Rubber Plantation with Different Ages

以生长在3 a和5 a树龄橡胶林下的谢君魔芋为实验材料,探索不同树龄橡胶林下谢君魔芋的光合作用和光合诱导能力,以期揭示喜阴作物谢君魔芋对不同树龄橡胶林下光的适应性。结果表明,在5 a橡胶林下谢君魔芋的暗呼吸(p<0.05)、光补偿点(p<0.01)、光饱和点(p=0.459)明显较小。在3 a橡胶林下谢君魔芋完成30%、50%、90%光合诱导进程的时间明显较短;相对应地光合诱导1、5、10 min时的诱导状态相对较高。这些结果说明,遮阴度增加时,谢君魔芋通过减小暗呼吸速率、光补偿点等光合生理行为,降低呼吸消耗、增强对低光的利用能力来维持碳收获,从而保证自身的正常生长;另一方面,遮阴度增加将导致谢君魔芋的光合诱导速率相对较慢,从而限制其对光斑的利用效率。因此,生产实践中,当橡胶林冠层的遮阴度过高时,可适当采取修枝措施,增强林下套种的谢君魔芋的光合作用能力和光斑利用效率。

The purpose of the present study was to investigate the photosynthetic capacity and photosynthetic induction of Amorphophallus xiei, and to reveal the light adaptative mechanism of A. xiei grown under rubber plantation with different ages. The photosynthetic capacity and, photosynthetic induction characteristics were examined in A. xiei grown under rubber plantation with 3-and 5-year-old（3 a and 5 a）. The result demonstrated that dark respiration rate（P〈0.05）, light compensation point（P〈0.01） and light saturation point（p =0.459） significantly decreased in individuals grown under 5a rubber plantation. Meanwhile, in the process of photosynthetic induction, the time to reach 30%, 50% and 90% maximum photosynthesis were shorter and the induction state of 1 min, 5 min, 10 min were higher under the 3a rubber plantation. Those suggested that, with the increase in shade degree, the normal growth of A. xiei is depending on the decrease in dark respiration and light compensating point both of which maintains the harvest of carbon by enhancing utilization of low light and reducing respiration consumpation.On the other hand, the photosynthetic induction rate became slower and the use efficiency of sunflecks was depressed with the increase in shade degree. Thus, in the production practice, rubber tree branches should be pruned moderately to enhance the photosynthetic capacity and the utilization of sunflecks of A. xiei, when the shade degree was too high.