To explore the photosynthetic capacity and the leaf photosynthetic apparatus for plants with different life forms, CO2 response curves of 7 woody species and 4 herbaceous species were fitted by the modified rectangular hyperbolic model and the FvCB model, and the photosynthetic parameters, including maximum net photosynthetic rate (Pn max), maximal Rubisco carboxylation rate (Vc max), maximal electron transport rate (Jmax), day respiration (Rd), and mesophyll resistance to CO2 transport (rm), were compared among different woody species, among different herbaceous species, and between woody and herbaceous life-forms, respectively. The results showed Pn max of seven woody species descended in the order of Sapium sebiferum and Boehmeria nivea ＞ Machilus pingii and Pittosporum tobira ＞ Cyclobalanopsis glauca, Castanopsis sclerophylla, and Quercus nuttallii. Vc max of S. sebiferum, B. nivea, M. pingii, and P. tobira was significantly higher than that of C. glauca and C. sclerophylla. Jmax of woody species was in descending order as S. sebiferum ＞ B. nivea and P. tobira ＞ Q. nuttallii, C. sclerophylla, and C. glauca. rm of M. pingii and C. sclerophylla was higher than that of S. sebiferum, P. tobira and B. nivea. Pn max of Phytolacca acinosa was significantly higher than that of Ageratum conyzoides and Achyranthes aspera. There was no significant difference in Vc max among 4 herbaceous species. Jmax of P. acinosa was higher than that of A. conyzoides. rm of S. nigrum and A. aspera was higher than that of A. conyzoides. Rd of P. acinosa was higher than that of A. conyzoides and A. aspera. The photosynthetic parameters (Pn max, Vc max, Jmax and rm) of woody species were significantly higher than those of herbaceous species, but no significant difference was found in Rd between woody and herbaceous species. In conclusion, the difference in photosynthetic capacity among different species and between the two plant life-forms resulted from the difference in Rubisco carboxylation capacity, electron transport capacity, and mesophyll resistance among these species.
为研究不同生活型植物的光合能力及其叶片光合机构,采用直角双曲线修正模型和C3植物FvCB模型对7种木本植物和4种草本植物的CO2响应曲线进行拟合,并对不同木本植物、不同草本植物和2种生活型植物的最大净光合速率(Pn max)、Rubisco酶最大羧化速率(Vc max)、最大电子传递速率(Jmax)、光合暗呼吸速率(Rd)和叶肉阻力(rm)等参数进行比较.结果表明: 7种木本植物Pn max大小顺序为乌桕、苎麻>润楠、海桐>青冈、苦槠、娜塔栎;乌桕、苎麻、润楠和海桐的Vc max显著大于青冈和苦槠;Jmax大小顺序为乌桕>苎麻、海桐>娜塔栎、苦槠和青冈;润楠和苦槠的rm显著大于乌桕、海桐和苎麻.商陆的Pn max显著大于藿香蓟和土牛膝;4种草本植物的Vc max无显著差异;商陆的Jmax显著大于藿香蓟;龙葵和土牛膝的rm显著大于藿香蓟;商陆的Rd显著大于藿香蓟和土牛膝.木本植物的Pn max、Vc max、Jmax和rm光合参数均显著大于草本植物,但二者的Rd无显著差异.不同物种之间以及2种生活型植物光合能力的差异主要是由叶片内部Rubisco酶羧化能力、电子传递能力和叶肉阻力等差异引起的.
Keywords: FvCB model; herbaceous species; photosynthetic capacity; physiological and biochemical cha-racteristics; woody species.