Do stomata optimize turgor-driven growth? A new framework for integrating stomata response with whole-plant hydraulics and carbon balance

Aaron Potkay, Xue Feng

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


Every existing optimal stomatal model uses photosynthetic carbon assimilation as a proxy for plant evolutionary fitness. However, assimilation and growth are often decoupled, making assimilation less ideal for representing fitness when optimizing stomatal conductance to water vapor and carbon dioxide. Instead, growth should be considered a closer proxy for fitness. We hypothesize stomata have evolved to maximize turgor-driven growth, instead of assimilation, over entire plants' lifetimes, improving their abilities to compete and reproduce. We develop a stomata model that dynamically maximizes whole-stem growth following principles from turgor-driven growth models. Stomata open to assimilate carbohydrates that supply growth and osmotically generate turgor, while stomata close to prevent losses of turgor and growth due to negative water potentials. In steady state, the growth optimization model captures realistic stomatal, growth, and carbohydrate responses to environmental cues, reconciles conflicting interpretations within existing stomatal optimization theories, and explains patterns of carbohydrate storage and xylem conductance observed during and after drought. Our growth optimization hypothesis introduces a new paradigm for stomatal optimization models, elevates the role of whole-plant carbon use and carbon storage in stomatal functioning, and has the potential to simultaneously predict gross productivity, net productivity, and plant mortality through a single, consistent modeling framework.

Original languageEnglish (US)
Pages (from-to)506-528
Number of pages23
JournalNew Phytologist
Issue number2
StatePublished - Apr 2023

Bibliographical note

Funding Information:
AP and XF acknowledge the support from the National Science Foundation CAREER award DEB‐2045610. We thank Antoine Cabon and Gerard Sapes for commentating on an early version of the manuscript. We are grateful to Tom Buckley and two other anonymous reviewers who provided suggestions and insights to improve the manuscript.

Publisher Copyright:
© 2022 The Authors. New Phytologist © 2022 New Phytologist Foundation.


  • dynamic optimality
  • nonstructural carbohydrates
  • source–sink dynamics
  • stomatal optimization
  • tree growth
  • tree hydraulics
  • turgor-driven expansion

PubMed: MeSH publication types

  • Journal Article
  • Research Support, U.S. Gov't, Non-P.H.S.


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