2种菊科入侵杂草光合特性的比较

Comparison of Photosynthetic Characteristics between Two Asteraceae Invasive Species

藿香蓟(Ageratum conyzoides)与金腰箭(Synedrella nodiflora)是能较好地共存于同一群落中的2种外来入侵植物。采用LI-6400便携式光合作用测定系统对金腰箭和藿香蓟的光合指标进行测定,旨在探讨2种入侵植物共存的光合生理基础。结果表明:①藿香蓟与金腰箭均存在"光合午休",二者的日平均净光合速率(Pn)无显著差异。②藿香蓟的光饱和点(1395μmol.m-2.s-1)与金腰箭(1380μmol.m-2.s-1)无显著差异,而其光补偿点(41.91μmol.m-2.s-1)极显著低于金腰箭(65.70μmol.m-2.s-1)。③藿香蓟与金腰箭的CO2饱和点均在1200μmol.m-2.s-1左右,但藿香蓟的CO2补偿点比金腰箭低约30%。总体来看,藿香蓟与金腰箭均为典型的阳生性植物,其光合特性差异主要体现在补偿点上,藿香蓟对光照和CO2的梯度变化适应的范围稍宽于金腰箭,但金腰箭对高浓度的CO2环境有更明显的响应。

Field investigation results showed that some invasive species could coexist very well in the same community, such as Ageratum conyzoides and Synodrella nodiflora. Using a field photo6ynthesis measurement system （ Li-6400 ）, photosynthetic indexes of A. conyzoides and S. nodiflora were determined, aiming to discuss the photosynthesis mechanism of coexistence for two invasive plants. Results showed that： （i） Net photosynthetic rates （Pn） ofA. conyzoldes and $. nod^fl.ora both displayed ＇double-peak＇ pattern under natural conditions in a day, but there was no significant differences for average daily Pn between A. conyzoides and S. nodiflor. （ii） LSP of A. conyzoid （ 1395μmol·m-2· s-1 ）was almost equal to that of S. nod/tot （ 1380μmol·m-2· s-1 ）, hut LCP of A. conyzoides （41.91 μmol·m-2· s-1 ） was greatly lower than that of S. nodiflor （65.70μmol·m-2· s-1）. （iii） CSP of A. conyzoides and S. nodiflora were about 1200 μmol·m-2· s-1 , but CCP of A. conyzolde was low about 30 % than that of S. nod/flor. In short, both ofA. conyzoides and S. nod/flora are belong to the typical （strong light-loving） heliophytes, and the difference of photosynthetic characteristics is mainly embodied in LCP and CCP between A. conyzoide~ and S. nodO^ora, the ecological amplitude of A. conyzoid~ is wider than that of S. nodiflora to the change of light intensity or CO2 concentratlon, however, S. nod/flora＇ s response to a high concentration of CO2 is more obvious than A. conyzoides. Ecological niche differentiation of A. conyzoides and S. nod/flora should be further studied.