濒危植物毛瓣金花茶与其同属广布种茶光合特性的比较

Comparison of photosynthetic characteristics between an endangered species Camellia pubipetala and its widespread congener C. sinensis

关键词:  毛瓣金花茶  茶  光合特性  光响应曲线  CO₂响应曲线

Key words:  Camellia pubipetala   C. sinensis  photosynthetic characteristics  light response curves  CO₂ response curves

摘要:

毛瓣金花茶为山茶科山茶属植物,该研究分别对野生种群和栽培种群的毛瓣金花茶及其同属广布种茶的光合特性进行了测定及差异比较。结果表明:在野生和栽培环境下,毛瓣金花茶的光补偿点(LCP)(分别为1.17和3.87 μmol·m^-2·s^-1)和光饱和点(LSP)(分别为395.8和423.6 μmol·m^-2·s^-1)均较低,最大净光合速率(P_max)(分别为4.25和3.91 μmol·m^-2·s^-1)较小,是典型的阴生植物; 而茶的LCP(分别为6.57和9.09 μmol·m^-2·s^-1)较低,LSP(分别为765.0和809.6 μmol·m^-2·s^-1)较高,P_max(分别为9.37和9.75 μmol·m^-2·s^-1)较大,为耐荫植物。野生和栽培的毛瓣金花茶的P_max、表观量子效率(AQY)、最大羧化速率(V_cmax)、最大电子传递速率(J_max)和潜在最大净光合速率(P_max)均显著低于茶(P<0.05),这表明毛瓣金花茶的光合能力和CO₂利用能力都比茶要弱。栽培的毛瓣金花茶叶片的Chla、Chlb、Chl(a+b)含量与茶相比无显著差异(P>0.05),表明毛瓣金花茶较低的光合能力与其叶绿素含量无关。野生和栽培的毛瓣金花茶的叶面积与茶相比无显著差异(P>0.05),而比叶重则显著高于茶(P<0.05),与茶相比,毛瓣金花茶对光强的适应范围狭窄,光合能力和CO₂利用能力低下,这可能是其分布狭窄的重要生理原因。

Abstract:

The photosynthetic characteristics of the endangered species Camellia pubipetala and its widespread congener C. sinensis in both wild and cultivated populations were studied. The results showed that the wild and cultivated C. pubipetala had low light compensation point(LCP)(1.17 and 3.87 μmol·m^-2·s^-1,respectively),light saturation point(LSP)(395.8 and 423.6 μmol·m^-2·s^-1,respectively),and maximum photosynthetic rate(P_max)(4.25 and 3.91 μmol·m^-2·s^-1,respectively)indicating that it was a shade plant,while C. sinensis had relatively low LCP (6.57 and 9.09 μmol·m^-2·s^-1,respectively),high LSP (765.0 and 809.6 μmol·m^-2·s^-1,respectively)and P_max (9.37 and 9.75 μmol·m^-2·s^-1,respectively)meaning that it was a shade tolerance plant. In comparison with C. sinensis,C. pubipetala had a significantly lower P_max,apparent quantum yield(AQY),maximum carboxylation rate(V_cmax),electronic transport rate(J_max)and potential maximum photosynthetic rate(Pmax)in wild and cultivated populations. The photosynthetic and CO₂ utilization capacity of C. pubipetala were significantly lower than those of C. sinensis. The contents of chlorophyll a,chlorophyll b and chlorophyll(a+b)in leaves of C. pubipetala were not significantly different from those of C. sinensis in cultivated population,which indicated that the low photosynthetic capacity of C. pubipetala had nothing to do with its chlorophyll content. There was no significant difference in single leaf area of the two plant species in both wild and cultivated population,while the leaf mass per area(LMA)of C. pubipetala was significantly higher than that of C. sinensis. Thus,it is inferred that in comparison with C. sinensis,the narrow adaptation range of light,low photosynthetic and CO₂ utilization capacity in C. pubipetala may be responsible for its narrow distribution.