Light use in relation to carbon gain in the mangrove, Avicennia marina, under hypersaline conditions
Light use in relation to carbon gain in the mangrove, Avicennia marina, under hypersaline conditions
复制标题
高盐条件下，白骨壤红树林的光利用与碳增益的关系
DOI：
--
复制
发表时间：
1999
期刊：
影响因子：
--
通讯作者：
M. Ball
中科院分区：
文献类型：
--
作者：
M. Sobrado;M. Ball
对红树林白骨壤(Avicennia marina(Forsk.)维耶尔。瓦尔澳大利亚(Astralasica(Walp.)莫尔登克，生长在相当于一倍和两倍海水(即35和60‰)的土壤盐度下。海水和高盐度站位的午间CO2同化速率平均值分别为7.6~0.7和4.3~0.3µmolm~(-2)S~(-1)。尽管有这种差异，但在两个地点，每个Chl和环氧化状态的叶黄素库大小是相似的。非光化学猝灭也表明颜料层有类似的能量耗散。根据荧光特性计算的电子传输速率也是相似的，超过了维持测量的同化速率的要求。然而，海水植物的细胞壁电导较低(75mmolm2 S-1)，而高盐植物的细胞壁电导下降到40mmolm-2 S-1。这将导致叶绿体(CC)中的二氧化碳浓度低于通过测量胞间二氧化碳浓度(Ci)而预期的浓度。在海水植物中，当Ci为245 mmoL-1时，Cc值为144µm ol-1，而在高盐度植物中，Cc和Ci分别为78和212 mmoL-1。CC的减少将提高光呼吸相对于同化的速率，较高的光呼吸速率足以解释明显的过剩电子传递速率。
Photosynthesis was studied in relation to light use in the mangrove, Avicennia marina (Forsk.) Vierh. var. australasica (Walp.) Moldenke, growing under soil salinities equivalent to one and two times seawater (i.e. 35 and 60‰). Midday CO2 assimilation rates averaged 7.6 0.7 and 4.3 0.3 µmol m–2 s–1 at the seawater and hypersaline sites, respectively. Despite this difference, xanthophyll pool sizes per Chl and epoxidation states were similar at both sites. Non-photochemical quenching also indicated comparable energy dissipation from pigment beds. Electron transport rates calculated from fluorescence characteristics were also similar and exceeded the requirements to sustain measured assimilation rates. However, cell wall conductance was low in seawater plants (75 mmol m2 s–1 ) and declined to 40 mmol m–2 s–1 in hypersaline plants. This would cause CO2 concentrations in chloroplasts (Cc ) to be lower than expected from measurements of intercellular CO2 concentrations (Ci ). In seawater plants, Cc was estimated to be 144 µmol mol–1 when Ci was 245 mmol mol–1, while values for Cc and Ci in hypersaline plants were 78 and 212 mmol mol–1, respectively. Reductions in Cc would enhance rates of photorespiration relative to assimilation, with the higher photorespiratory rates being sufficient to account for apparent excess electron transport rates.