B007-06
Detailed evaluation of the responses of sun-induced chlorophyll fluorescence and photosynthesis to large-scale drought events
Monday, 7 December 2020: 05:50
Virtual
Benjamin Dechant1, Youngryel Ryu2, Philipp Koehler3, Bolun Li4 and Jongmin Kim2, (1)Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul, South Korea, (2)Seoul National University, Seoul, Korea, Republic of (South), (3)California Institute of Technology, Pasadena, CA, United States, (4)Seoul National University, Research Institute of Agriculture and Life Sciences, Seoul, Korea, Republic of (South)
Abstract:
Extreme drought events are a threat to natural ecosystems as well as global food security and tend to occur with both higher frequency and severity due to global climate change. Therefore, finding suitable approaches to detect early indications of plant stress as well as quantify reductions in photosynthesis is of great importance. Sun-induced chlorophyll fluorescence (SIF) has been identified as promising tool to monitor early drought responses as it contains not only information on the canopy structural changes but also a physiological signal that is expected to be more sensitive to drought. Previous studies indeed reported an earlier and stronger response of SIF to drought compared to other approaches for individual drought events. However, a detailed analysis of the responses of the structural and physiological components to drought stress has not been reported so far. Here, we attempted to conduct such an analysis for a collection of major large-scale drought events.
We confirmed that SIF rather consistently showed an earlier and stronger response to drought compared to variables that capture only the canopy structural response. This more sensitive response of SIF was caused by the physiological component which showed early decreases that coincided with those of estimated photosynthetic light use efficiency. Moreover, part of the structural response even showed increases during drought and therefore normalizing for this component further improved the drought sensitivity of SIF. While SIF showed good performance for early drought detection, its response differed considerably from that of global photosynthesis products. In particular, SIF showed considerably smaller and shorter decreases compared to estimated photosynthesis for most drought events, while it even showed a stronger response in other events. This suggests that SIF might be more useful for monitoring certain aspects of vegetation stress rather than actual photosynthesis during drought events.
