Yazen Al-Salman

Introduction Stomata are small, adjustable pores flanked by two specialized cells (guard cells) that regulate leaf CO2 and water vapor exchange. This function is pivotal for plants, as there is a trade-off between CO2 entry into the leaves for photosynthesis and water vapor loss, which drives nutrient uptake and leaf cooling.

Contents Summary 1 I. Introduction 1 II. The evolution and physiology of C4 photosynthesis 2 III. Limitations of C4 photosynthesis under climate change 4 IV. Stomatal conductance and leaf traits under climate change 8 V. Scaling iWUE to WUEp in C4 crops 10 VI. Improving iWUE in C4 crops under climate change 11 VII. Conclusions and future directions 12 Acknowledgements 13 References 13 I.

Original Article This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as doi:10.1111/tpj.16346. SUMMARY Most studies assume midday gas exchange measurements capture the leaf's daytime performance.