Differential responses to two heatwave intensities in a Mediterranean citrus orchard are identified by combining measurements of fluorescence and carbonyl sulfide (COS) and CO2 uptake

Amnon Cochavi, Madi Amer, Rafael Stern, Fyodor Tatarinov, Mirco Migliavacca, Dan Yakir

Research output: Contribution to journalArticlepeer-review

16 Scopus citations

Abstract

The impact of extreme climate episodes such as heatwaves on plants physiological functioning and survival may depend on the event intensity, which requires quantification. We unraveled the distinct impacts of intense (HW) and intermediate (INT) heatwave days on carbon uptake, and the underlying changes in the photosynthetic system, in a Mediterranean citrus orchard using leaf active (pulse amplitude modulation; PAM) and canopy level passive (sun-induced; SIF) fluorescence measurements, together with CO2, water vapor, and carbonyl sulfide (COS) exchange measurements. Compared to normal (N) days, gross CO2 uptake fluxes (gross primary production, GPP) were significantly reduced during HW days, but only slightly decreased during INT days. By contrast, COS uptake flux and SIFA (at 760 nm) decreased during both HW and INT days, which was reflected in leaf internal CO2 concentrations and in nonphotochemical quenching, respectively. Intense (HW) heatwave conditions also resulted in a substantial decrease in electron transport rates, measured using leaf-scale fluorescence, and an increase in the fractional energy consumption in photorespiration. Using the combined proxy approach, we demonstrate a differential ecosystem response to different heatwave intensities, which allows the trees to preserve carbon assimilation during INT days but not during HW days.

Original languageEnglish
Pages (from-to)1394-1406
Number of pages13
JournalNew Phytologist
Volume230
Issue number4
DOIs
StatePublished - 1 May 2021
Externally publishedYes

Keywords

  • carbonyl sulfide
  • citrus
  • heatwave
  • leaf relative uptake
  • stress response
  • sun-induced fluorescence

ASJC Scopus subject areas

  • Physiology
  • Plant Science

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