滇青冈光合响应特征曲线研究

Study on Photosynthetic Response Curves of Cyclobalanopsis glaucoides

为研究滇青冈在不同光合有效辐射与CO2浓度下的光合特性及光合作用潜力,以西南林业大学校园内的14年生滇青冈为对象,采用LI-6400便携式光合作用系统的红蓝光源与外接CO2钢瓶,原位测量滇青冈叶片的净光合速率(Pn)对光合有效辐射(PAR)与胞间CO2浓度(Ci)的响应曲线,并拟合得到了表观量子效率(Q)、最大光合速率(Pmax)、暗呼吸速率(Rd)、光补偿点(LCP)、光饱和点(LSP)、表观羧化效率(Vc)、最大电子传递速率(Jmax)、光呼吸速率(Rp)、最大羧化效率(Vcmax)、Rubisco含量、CO2补偿点(CCP)、CO2饱和点(CSP)等重要光合参数。结果表明:滇青冈叶片的Pn在PAR≤200μmol/(m2.s)范围呈直线上升趋势,随后逐渐增加至最大值,在PAR≥800μmol/(m2.s)后开始缓慢下降。滇青冈的Pn/Ci曲线显示:在Ci≤400μmol/mol时,Pn上升速度较快,此后随着Ci浓度的逐渐升高,Pn也逐渐接近饱和状态。滇青冈的LCP较低,LSP也并不高,表现出较强的阴生植物特征。此外,滇青冈的Vc、Jmax、Vcmax、Rubisco含量均较低,导致其较低的光合能力。对于滇青冈的造林种植管理,应主要利用滇中高原石灰岩地区的半阴坡、阴坡或其他形式的适当遮荫生境条件。

The photosynthetic characteristics and photosynthesis potential of Cyclobalanopsis glaucoides under conditions with different photosynthetic active radiation （PAR） and CO2 concentration （Ci） were studied by taking 14-year-old Cyclobalanopsis glaucoides grown on the campus of Southwest Forestry University as study objects, and the response curve of net photosynthetic rate （Pn） to photosynthetic active radiation （PAR） and CO2 concentration （ Ci ） were measured in situ by using a LI - 6400 portable photosynthesis system with 6400 - 02B LED light source and CO2 steel cylinder. The important photosynthetic parameters including the apparent quantum yield （ Q）, maxi- mum photosynthetic rate （Pmax）, dark respiration rate （Rd ）, light compensation point （LCP）, light saturation point （LSP）, apparent carboxylation efficiency （Vc）, maximum electron transport rate （Jmax）, light respiration rate （Rp）, Maximum carboxylation efficiency （Vcmax）, rubisco content （Rubisco）, CO2 compensation point （CCP）, CO2 saturation point （CSP） were fitted and estimated. The resuRs showed that the net photosynthetic rate（ Pn ） increased rapidly when the PAR value was under 200 μ moL/（ m2 s） , then the Pn grew slowly till reached the maximum value, afterwards it dropped slightly when the PAR value was above 800 μmol/（ m2 s）. The photosyn- thetic CO2 response （Pn/Ci） curves of C. glaucoides showed that Pn value increased fast when Ci was under 400 μmol/mol, then it grew gradually till it reached saturation status as Ci increased. Both of the LCP and LSP values of C. glaucoides were lower, indicating that this tree species was of shade tolerant characteristics. Moreover, the study showed that the photosynthetic capacity of C. glaucoides was lower because of the lower Vc, Jmax, Vcmax and Rubisco values. Based on the characteristics of this tree species, it was proposed that C. glaucoides should be plan- ted on the half shade slope, shade slope and/or other appropriate shade habitat conditions at limestone region in the middle area of Yunnan Province. Key words：Cyclobalanopsis glaucoides; photosynthetic characteristics; photosynthetic light response curve; photosynthetic CO2 response curve