Photosynthetic rapid light curves (RLC) of Thalassia testudinum exhibit diurnal variation
Photosynthetic rapid light curves (RLC) of Thalassia testudinum exhibit diurnal variation
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DOI：
10.1016/j.jembe.2006.10.056
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发表时间：
2007-04-16
影响因子：
2
通讯作者：
Blum, J. E.
中科院分区：
文献类型：
--
作者：
Belshe, E. F.;Durako, M. J.;Blum, J. E.
在美国佛罗里达湾，采用脉冲幅度调制荧光法（PAM）和快速光变曲线法（RLC）对海扁藻（Thalassia testudinum）的生理状况进行了景观尺度的监测。PAM荧光测定法提供了关于光合作用状态的快速、非侵入性和定量的生理信息。然而，以前的有效和最大量子产率的研究表明，当从生物体尺度到景观尺度扩展测量时会出现问题，主要是由于时间和辐照引起的生物生理学变化。本文利用RLC分析了10个流域和两个年度间光合特性的日变化和空间变化。由于RLC测量的是光化辐照度变化范围内的有效量子产额，因此我们假设响应参数对昼夜光历史效应的敏感性较低。我们的研究结果表明，RLC参数，α和ETR（最大值），显着的昼夜变化，如先前发现的最大和有效的量子产率，但昼夜模式是可变的10个盆地。这两个跨流域和年间的比较混淆的昼夜变化和统计分析比较上午，中午和下午的时间段无法明确辨别一天中的哪个时间是最适合评估的T testudinum的相对生理状态。然而，池RLC数据在流域尺度上显示，在这个海草与流域级形态变化一致的流域差异和景观规模的趋势。因此，PAM荧光法可能是有用的景观尺度监测工具在一定的限制。当在大的空间和时间尺度上使用这种方法时，必须考虑日变化。(c)2006 Elsevier B.V.保留所有权利。
The use of pulse-amplitude-modulated fluorometry (PAM) and rapid light curves (RLC) were evaluated for monitoring the physiological condition of the seagrass, Thalassia testudinum, at the landscape scale in Florida Bay, USA. PAM fluorometry provides rapid, non-invasive, and quantitative physiological information on the state of photosynthesis. Yet, previous studies of effective and maximum quantum yields have shown that problems arise when expanding measurements from the organismal scale to the landscape scale, mainly due to temporal and irradiance-induced changes in photophysiology. Here, the magnitude of diurnal and spatial variation of photosynthetic characteristics among 10 sample basins and between two sample years was investigated using RLCs. Because RLCs measure effective quantum yields over a range of changing actinic irradianccs, we hypothesized that the response parameters might be less sensitive to diurnal light history effects. Our results indicate that the RLC parameters, alpha and ETR(max), significantly changed diurnally, as was previously found for both maximum and effective quantum yields, but the diurnal patterns were variable among the 10 basins. Both among-basin and between-year comparisons were confounded by diurnal variation and statistical analyses comparing morning, mid-day, and afternoon time periods were unable to definitively discern which time of day was best suited for assessing the relative photophysiological status of T testudinum. However, pooling RLC data at the basin scale revealed among-basin differences and landscape scale trends that were consistent with basin-level morphometric variation in this seagrass. Thus, PAM fluorometry may be useful as a landscape scale monitoring tool within certain constraints. When using this approach over large spatial and temporal scales, diurnal variability must be considered. (c) 2006 Elsevier B.V. All rights reserved.