Exploring optimal stomatal control under alternative hypotheses for the regulation of plant sources and sinks

• DOI: 10.1111/nph.17795
• Publication Date: 2021-10-13T01:39:31Z
• Authors: Roderick Dewar; Teemu Hölttä; Yann Salmon
• Keywords: Turgor pressure; Sink (geography)

Summary Experimental evidence that nonstomatal limitations to photosynthesis (NSLs) correlate with leaf sugar and/or water status suggests the possibility stomata adjust maximise through a trade‐off between CO 2 supply and NSLs, potentially involving source–sink interactions. However, mechanisms regulating NSLs sink strength, as well their implications for stomatal control, remain uncertain. We used an analytically solvable model explore optimal control under alternative hypotheses source regulation. assumed either concentration or potential regulates phloem turgor pressure unloading. All led realistic responses light, air humidity, including conservative behaviour intercellular‐to‐atmospheric ratio. Sugar‐regulated water‐regulated are distinguished by presence/absence of closure response changing strength. Turgor‐regulated sugar‐regulated unloading drought avoidance/occurrence negative turgor. Results from girdling experiments on Pinus sylvestris , Betula pendula Populus tremula Picea abies saplings consistent turgor‐regulated Our analytical results provide simple representation above‐ground below‐ground environmental factors activity.