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Drought responses of two gymnosperm species with contrasting stomatal regulation strategies under elevated [CO2] and temperature
journal contributionposted on 2023-05-19, 05:45 authored by Duan, H, Anthony O'GradyAnthony O'Grady, Duursma, RA, Choat, B, Huang, G, Smith, RA, Jiang, Y, Tissue, DT
Future climate regimes characterized by rising [CO2], rising temperatures and associated droughts may differentially affect tree growth and physiology. However, the interactive effects of these three factors are complex because elevated [CO2] and elevated temperature may generate differential physiological responses during drought. To date, the interactive effects of elevated [CO2] and elevated temperature on drought-induced tree mortality remain poorly understood in gymnosperm species that differ in stomatal regulation strategies. Water relations and carbon dynamics were examined in two species with contrasting stomatal regulation strategies: Pinus radiata D. Don (relatively isohydric gymnosperm; regulating stomata to maintain leaf water potential above critical thresholds) and Callitris rhomboidea R. Br (relatively anisohydric gymnosperm; allowing leaf water potential to decline as the soil dries), to assess response to drought as a function of [CO2] and temperature. Both species were grown in two [CO2] (Ca (ambient, 400 μl l−1) and Ce (elevated, 640 μl l−1)) and two temperature (Ta (ambient) and Te (ambient +4 °C)) treatments in a sun-lit glasshouse under well-watered conditions. Drought plants were then exposed to a progressive drought until mortality. Prior to mortality, extensive xylem cavitation occurred in both species, but significant depletion of non-structural carbohydrates was not observed in either species. Te resulted in faster mortality in P. radiata, but it did not modify the time-to-mortality in C. rhomboidea. Ce did not delay the time-to-mortality in either species under drought or Te treatments. In summary, elevated temperature (+4 °C) had greater influence than elevated [CO2] (+240 μl l−1) on drought responses of the two studied gymnosperm species, while stomatal regulation strategies did not generally affect the relative contributions of hydraulic failure and carbohydrate depletion to mortality under severe drought.
Publication titleTree Physiology: An International Botanical Journal
Department/SchoolSchool of Natural Sciences
Place of publication202, 3994 Shelbourne St, Victoria, Canada, Bc, V8N 3E2
Rights statementCopyright 2015 The Author