Ríos-Rojas Liliana, Morales-Moraga David, Alcalde José A, Gurovich Luis A
a Pontificia Universidad Católica de Chile ; Santiago , Chile.
Plant Signal Behav. 2015;10(2):e976487. doi: 10.4161/15592324.2014.976487.
The electrical response of plants to environmental stimuli can be measured and quantitatively related to the intensity of several stimulating sources, like temperature, solar radiation, soil water content, evapotranspiration rates, sap flow and dendrometric cycles. These relations can be used to assess the influence of different environmental situations on soil water availability to plants, defined as a steady state condition between leaf transpirative flow and soil water flow to plant roots. A restricted soil water flow due to soil dryness can trigger water stress in plants, if the atmospheric evaporative demand is high, causing partial stomata closure as a physiological response to avoid plant dehydration; water stressed and unstressed plants manifest a differential electrical response. Real time plant electrical response measurements can anticipate actions that prevent the plant reaching actual stress conditions, optimizing stomata gas exchange and photosynthetic rates. An electrophysiological sensor developed in this work, allows remote real-time recording information on plant electrical potential (EP) in the field, which is highly related to EP measurements obtained with a laboratory Keithley voltmeter sensor used in an highly controlled experimental setup. Our electrophysiological sensor is a wireless, autonomous devise, which transmits EP information via Internet to a data server. Using both types of sensors (EP electrodes with a Keithley voltmeter and the electrophysiological sensor), we measured in real time the electrical responses of Persea americana and Prunus domestica plants, to induced water deficits. The differential response for 2 scenarios: irrigation and water restriction is identified by a progressive change in slope on the daily maximal and minimal electric signal values in stressed plants, and a zero-slope for similar signals for well-watered plants. Results show a correspondence between measured signals obtained by our electrophysiological sensor and the EP electrodes connected to the Keithley voltmeter in each irrigation stage. Also, both sensors show a daily cyclical signal (circadian cycle).
植物对环境刺激的电响应可以被测量，并与多种刺激源的强度建立定量关系，如温度、太阳辐射、土壤含水量、蒸散速率、液流和树木生长周期。这些关系可用于评估不同环境状况对植物可利用土壤水分的影响，土壤水分可利用性被定义为叶片蒸腾流与土壤向植物根系的水流之间的稳态条件。如果大气蒸发需求较高，土壤干燥导致的土壤水流受限会引发植物水分胁迫，从而引起部分气孔关闭，这是一种避免植物脱水的生理反应；水分胁迫和未受胁迫的植物表现出不同的电响应。实时测量植物电响应可以预测预防植物达到实际胁迫条件的措施，优化气孔气体交换和光合速率。在这项工作中开发的一种电生理传感器，能够在田间远程实时记录植物电势（EP）信息，这与在高度受控实验装置中使用实验室吉时利电压表传感器获得的EP测量值高度相关。我们的电生理传感器是一种无线自主设备，它通过互联网将EP信息传输到数据服务器。使用这两种类型的传感器（带有吉时利电压表的EP电极和电生理传感器），我们实时测量了鳄梨和李子树对诱导水分亏缺的电响应。通过受胁迫植物每日最大和最小电信号值斜率的逐渐变化，以及浇水良好植物类似信号的零斜率，识别出灌溉和水分限制这两种情况下的差异响应。结果表明，在每个灌溉阶段，我们的电生理传感器获得的测量信号与连接到吉时利电压表的EP电极之间具有对应关系。此外，两种传感器都显示出每日周期性信号（昼夜节律周期）。
