Drought-induced shoot dieback starts with massive root xylem embolism and variable depletion of nonstructural carbohydrates in seedlings of two tree species

Jesús Rodríguez-Calcerrada, Meng Li, Rosana López, Francisco Javier Cano, Jacek Oleksyn, Owen K. Atkin, Pilar Pita, Ismael Aranda, Luis Gil

Research output: Contribution to journalArticlepeer-review

30 Scopus citations

Abstract

Combining hydraulic- and carbon-related measurements helps to understand drought-induced plant mortality. Here, we investigated the role that plant respiration (R) plays in determining carbon budgets under drought. We measured the hydraulic conductivity of stems and roots, and gas exchange and nonstructural carbohydrate (NSC) concentrations of leaves, stems and roots of seedlings of two resprouting species exposed to drought or well-watered conditions: Ulmus minor (riparian tree) and Quercus ilex (dryland tree). With increasing water stress (occurring more rapidly in larger U. minor), declines in leaf, stem and root R were less pronounced than that in leaf net photosynthetic CO2 uptake (Pn). Daytime whole-plant carbon gain was negative below −4 and −6 MPa midday xylem water potential in U. minor and Q. ilex, respectively. Relative to controls, seedlings exhibiting shoot dieback suffered c. 80% loss of hydraulic conductivity in both species, and reductions in NSC concentrations in U. minor. Higher drought-induced depletion of NSC reserves in U. minor was related to higher plant R, faster stomatal closure, and premature leaf-shedding. Differences in drought resistance relied on the ability to maintain hydraulic conductivity during drought, rather than tolerating conductivity loss. Root hydraulic failure elicited shoot dieback and precluded resprouting without root NSC reserves being apparently limiting for R.

Original languageEnglish (US)
Pages (from-to)597-610
Number of pages14
JournalNew Phytologist
Volume213
Issue number2
DOIs
StatePublished - Jan 1 2017

Keywords

  • carbon starvation
  • cavitation
  • die-off
  • forest decline
  • phloem failure
  • plant mortality
  • stem growth

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