太行山低山丘陵区5种木本植物光合特性的比较

Photosynthesis,light-use efficiency and water-use efficiency for woody species in the hilly area of the Taihang Mountains

植物种的选择是太行山低山丘陵区植被恢复与重建的关键问题之一。利用LI-6400xT光合系统分析仪研究了5种木本植物的光合日进程特性、光能利用效率及水分利用效率。结果表明:①火炬树Rhus typhina,刺槐Robiniapseudoacacia,臭椿Ailanthus altissima,荆条Vitex negundo var.heterophylla,酸枣Ziziphus jujuba var.spinosa的最大净光合效率出现在中午12:00,均无光合午休现象;②比较5种木本植物的光能利用效率后发现,火炬树的光能利用效率最高,其光能利用效率与臭椿、荆条的光能利用效率差异显著(P<0.05),与刺槐、酸枣的光能利用率差异不显著(P>0.05),说明火炬树、刺槐及酸枣的光能利用效率较高;③除酸枣外,5种木本植物的水分利用效率日变化曲线均呈"V"型曲线,酸枣的水分利用效率呈"W"型曲线。火炬树的水分利用效率最高,与臭椿、荆条、酸枣的水分利用效率差异显著(P<0.05),与刺槐差异不显著(P>0.05),表明火炬树和刺槐的水分利用效率较高。因此,火炬树和刺槐在秋季具较高的光能及水分利用效率,基于两者为外来树种,需慎重考虑将它们作为该地区的植被恢复树种。

To determine woody species for vegetative restoration in the hilly areas of the Taihang Mountains,the diurnal photosynthetic course of five woody plants（Rhus typhina,Robinia pseudoacacia,Ziziphus jujuba var.spinosa,Ailanthus altissima,and Vitex negundo var.heterophylla） was measured using a LI-6400xT portable photosynthetic system.Light-use efficiency and water-use efficiency were calculated and analyzed with formulas ELU = Pn/PAR and EWU = Pn/E respectively.Results showed that：（1） maximum net photosynthetic efficiency for all five trees occurred at 12 ： 00 noon with no midday depression.（2） Light-use efficiency of R.typhina,R.pseudoacacia,and Z.jujuba var.spinosa were not significantly（LSD,P0.05） different,but they were significantly greater（P0.05） than A.altissima and V.negundo var.heterophylla.（3） The diurnal changes curves of water-use efficiency in Z.jujuba var.spinosa belonged to a ＂W-type＂,while the other four woody species a ＂V-type＂.Water-use efficiency of R.typhina was not significantly different from R.pseudoacacia（P0.05）,but was significantly different from Z.jujuba var.spinosa,A.altissima,and V.negundo var.heterophylla（P0.05）.Thus,light and water-use efficiencies of the exotic species R.typhina and R.pseudoacacia were better than the other three species.