四种樟属树种幼树的光合生理特性比较

摘要

采用Li-6400光合测定仪系统研究了樟属树种香樟、岩桂、天竺桂、猴樟的幼树在不同生长季节的田间光合生理特性.结果表明,4种樟属树种幼树在春季、夏季的净光合速率日变化都呈“双峰”型曲线变化,出现典型的“光合午休”现象,并且第一峰值高于第二峰值;而在秋季各树种幼树的净光合速率日变化则都呈“单峰”型曲线变化.4种树幼树的光合作用生理指标各不相同,但光适应能力均较强；其中,净光合速率高低排序为香樟、猴樟、天竺桂、岩桂,光饱和点高低排序为香樟、猴樟、天竺桂、岩桂,光补偿点高低排序为天竺桂、猴樟、岩桂、香樟,表观量子效率高低排序为香樟、猴樟、天竺桂、岩桂,CO2补偿点高低排序为猴樟、天竺桂、岩桂、香樟.多元逐步回归分析结果表明,影响净光合速率的关键环境因子随树种不同而变化,对香樟的净光合速率有显著影响的因子是光合有效辐射、气孔导度和胞间CO2浓度,对岩桂和天竺桂的净光合速率有显著影响的因子是气温、气孔导度和胞间CO2浓度,对猴樟的光合速率有显著影响的因子是光合有效辐射和气温.%The Li-6400 photosynthetic apparatus system was used to study the photosynthetic physiological characteristics of young trees of Cinnamomum camphora (L.) Presl,C.petrophilum N.Chao,C.pedunculatum Sieb.and C.bodinieri Levl.in different growing seasons in the field.Results showed that the daily change of net photosynthetic rate (Pn) of the young trees of the 4 Cinnamomum species in spring and summer was bimodal curve with typical "midday depression of photosynthesis" phenomenon; and the first peak was higher than the second peak; the daily variation of net Pn in autumn was unimodal curve.The photosynthetic physiological indexes of the young trees of 4 species were not identical; but their light adaptability was all strong.Among them,the net Pn ranked from high to low as C.camphora,C.bodinieri,C.pedunculatum,C.petrophilum; light saturation point sequenced from high to low as C.camphora,C.bodinieri,C.pedunculatum,C.petrophilum; light compensation point sorted from high to low as C.pedunculatum,C.bodinieri,C petrophilum,C.camphora; apparent quantum efficiency ranked from high to low as C.camphora,C.bodinieri,C.pedunculatum,C.petrophilum;CO2 compensation point ranked from high to low as C.bodinieri,C.pedunculatum,C.petrophilum,C.camphora.Multiple stepwise regression analysis results showed that the key environmental factors that affected the net Pn differed with the different tree species,the net Pn of C.camphora was significantly influenced by photosynthetic effective radiation,stomatal conductance and intercellular CO2 concentration.For the net Pn of C.petrophilum and C.pedunculatum,the significant influencing factors were temperature,stomatal conductance and intercellular CO2 concentration; net Pn of C.bodinieri was significantly impacted by photosynthetic effective radiation and air temperature.