Conesa María R, Conejero Wenceslao, Vera Juan, Mira-García Ana Belén, Ruiz-Sánchez María Carmen
Irrigation Department, CEBAS-CSIC, Campus de Espinardo 25, 30100 Murcia, Spain.
Plants (Basel). 2023 Feb 17;12(4):907. doi: 10.3390/plants12040907.
This field experiment focuses on the effects of a heavy rainfall event (DANA, that occurred on 12-14 September 2019 (DOY, Day of the year, 255-257), in southern Spain on plant water status and the thermal response of nectarine trees. Two irrigation treatments were applied during the summer-autumn postharvest period (DOY 158-329): full-irrigated (CTL) and non-irrigated (DRY). Volumetric soil water content (θ), air temperature (Ta) and canopy temperature (Tc) were monitored in real-time and the crop water stress index (CWSI) was calculated. The difference in Tc between the DRY and CTL treatments (Tc' - Tc) is proposed as a new thermal indicator. Stem water potential (Ψ) and leaf gas exchange measurements were recorded on representative days. During the DANA event, only the Tc measured by the infrared radiometer sensors could be monitored. Therefore, the effects of the DANA forced the soil water content sensors to be switched off, which prevented Ψ and leaf gas exchange determinations from DOY 255 to 275. Before the DANA event, withholding irrigation caused a gradual decrease in the soil and plant water status in the DRY treatment. Significant differences appeared between treatments in the studied thermal indexes. Moreover, Tc' - Tc was more sensitive than Tc - Ta in assessing nectarine water stress. The effects of the DANA reduced these differences, suggesting different baselines for the calculation of CWSI. In this respect, the relationship Tc - Ta vs. VPD improved the coefficient of determination after the DANA event in full-irrigated trees. Similar values of Ψ and leaf gas exchange were found in both treatments after the DANA event, even though thermal indexes showed some significant differences. In addition, the strong relationship found between Tc - Ta and CWSI vs. Ψ worsened after DANA occurred, revealing a lower sensitivity of Ψ compared to canopy temperature to accurately assess nectarine water status in these saturated soil conditions. This research underlined the robustness of infrared thermography to continuously monitor plant water status under these extreme weather conditions.
该田间试验聚焦于2019年9月12日至14日（一年中的第255 - 257天）发生在西班牙南部的一场暴雨事件（达娜）对油桃树水分状况和热响应的影响。在夏秋收获后时期（一年中的第158 - 329天）采用了两种灌溉处理：充分灌溉（对照）和不灌溉（干旱）。实时监测土壤体积含水量（θ）、气温（Ta）和冠层温度（Tc），并计算作物水分胁迫指数（CWSI）。提出干旱处理与对照处理之间的Tc差值（Tc' - Tc）作为一种新的热指标。在代表性日期记录茎水势（Ψ）和叶片气体交换测量值。在达娜事件期间，只能监测红外辐射计传感器测量的Tc。因此，达娜事件的影响导致土壤水分含量传感器关闭，从而在一年中的第255天至275天无法进行Ψ和叶片气体交换测定。在达娜事件之前，停止灌溉导致干旱处理中土壤和植物水分状况逐渐下降。各处理在研究的热指标上出现显著差异。此外，在评估油桃水分胁迫方面，Tc' - Tc比Tc - Ta更敏感。达娜事件的影响减小了这些差异，表明计算CWSI的基线不同。在这方面，达娜事件后，充分灌溉树木中Tc - Ta与水汽压亏缺（VPD）的关系提高了决定系数。达娜事件后，尽管热指标存在一些显著差异，但两种处理中Ψ和叶片气体交换的值相似。此外，达娜事件发生后，Tc - Ta和CWSI与Ψ之间的强关系变差，表明在这些饱和土壤条件下，与冠层温度相比，Ψ在准确评估油桃水分状况方面的敏感性较低。这项研究强调了红外热成像技术在这些极端天气条件下连续监测植物水分状况的稳健性。
