Salvatori Nicole, Giorgio Alberti, Muller Onno, Rascher Uwe, Peressotti Alessandro
Department of Life Sciences, University of Trieste, 34127, Trieste, Italy.
Department of Agricultural, Food, Environmental and Animal Sciences, University of Udine, Via delle Scienze 206, 33100, Udine, Italy.
Plant Methods. 2021 Jun 30;17(1):69. doi: 10.1186/s13007-021-00772-z.
Obtaining instantaneous gas exchanges data is fundamental to gain information on photosynthesis. Leaf level data are reliable, but their scaling up to canopy scale is difficult as they are acquired in standard and/or controlled conditions, while natural environments are extremely dynamic. Responses to dynamic environmental conditions need to be considered, as measurements at steady state and their related models may overestimate total carbon (C) plant uptake.
In this paper, we describe an automatic, low-cost measuring system composed of 12 open chambers (60 × 60 × 150 cm; around 400 euros per chamber) able to measure instantaneous CO and HO gas exchanges, as well as environmental parameters, at canopy level. We tested the system's performance by simulating different CO uptake and respiration levels using a tube filled with soda lime or pure CO, respectively, and quantified its response time and measurement accuracy. We have been also able to evaluate the delayed response due to the dimension of the chambers, proposing a method to correct the data by taking into account the response time ([Formula: see text]) and the residence time (τ). Finally, we tested the system by growing a commercial soybean variety in fluctuating and non-fluctuating light, showing the system to be fast enough to capture fast dynamic conditions. At the end of the experiment, we compared cumulative fluxes with total plant dry biomass.
The system slightly over-estimated (+ 7.6%) the total C uptake, even though not significantly, confirming its ability in measuring the overall CO fluxes at canopy scale. Furthermore, the system resulted to be accurate and stable, allowing to estimate the response time and to determine steady state fluxes from unsteady state measured values. Thanks to the flexibility in the software and to the dimensions of the chambers, even if only tested in dynamic light conditions, the system is thought to be used for several applications and with different plant canopies by mimicking different environmental conditions.
获取瞬时气体交换数据是了解光合作用信息的基础。叶片水平的数据是可靠的，但由于这些数据是在标准和/或受控条件下获取的，而自然环境极具动态性，因此将其扩展到冠层尺度很困难。需要考虑对动态环境条件的响应，因为稳态下的测量及其相关模型可能会高估植物的总碳（C）吸收量。
在本文中，我们描述了一种自动、低成本的测量系统，该系统由12个开放式气室（60×60×150厘米；每个气室约400欧元）组成，能够在冠层水平测量瞬时CO和HO气体交换以及环境参数。我们分别使用装有苏打石灰或纯CO的管子模拟不同的CO吸收和呼吸水平，测试了该系统的性能，并量化了其响应时间和测量精度。我们还能够评估由于气室尺寸导致的延迟响应，提出了一种通过考虑响应时间（[公式：见正文]）和停留时间（τ）来校正数据的方法。最后，我们通过在波动和非波动光照下种植一种商业大豆品种来测试该系统，结果表明该系统足够快，能够捕捉快速的动态条件。在实验结束时，我们将累积通量与植物总干生物量进行了比较。
该系统略微高估了总碳吸收量（+7.6%），尽管不显著，这证实了其在冠层尺度测量总体CO通量的能力。此外，该系统结果准确且稳定，能够估计响应时间并从未稳态测量值确定稳态通量。由于软件的灵活性和气室尺寸，即使仅在动态光照条件下进行了测试，该系统仍被认为可通过模拟不同环境条件用于多种应用和不同的植物冠层。
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