Abstract
The opening and closing of stomata are controlled by the integration of environmental and endogenous signals. Here, we show the effects of combining elevated atmospheric carbon dioxide concentration (eCO2; 600 μmol mol-1) and warming (+2°C) on stomatal properties and their consequence to plant function in a Stylosanthes capitata Vogel (C3) tropical pasture. The eCO2 treatment alone reduced stomatal density, stomatal index, and stomatal conductance (gs), resulting in reduced transpiration, increased leaf temperature, and leading to maintenance of soil moisture during the growing season. Increased CO2 concentration inside leaves stimulated photosynthesis, starch content levels, water use efficiency, and PSII photochemistry. Under warming, plants developed leaves with smaller stomata on both leaf surfaces; however, we did not see effects of warming on stomatal conductance, transpiration, or leaf water status. Warming alone enhanced PSII photochemistry and photosynthesis, and likely starch exports from chloroplasts. Under the combination of warming and eCO2, leaf temperature was higher than that of leaves from the warming or eCO2 treatments. Thus, warming counterbalanced the effects of CO2 on transpiration and soil water content but not on stomatal functioning, which was independent of temperature treatment. Under warming, and in combination with eCO2, leaves also produced more carotenoids and a more efficient heat and fluorescence dissipation. Our combined results suggest that control on stomatal opening under eCO2 was not changed by a warmer environment; however, their combination significantly improved whole-plant functioning.
Highlights
Since the industrial revolution, anthropogenic activities have increased atmospheric carbon dioxide concentrations ([CO2]) from 270 μmol mol−1 to the more than 400 μmol mol−1 we see today (IPCC, 2018). [CO2] is expected to reach 600 μmol mol−1 by 2050 as modeled by the Representative Concentration Pathways (RCP; IPCC, 2018)
[CO2] Regulation of Legume Stomata elevated [CO2] coupled with the increased emissions of other greenhouses gases (GHG), such as methane (CH4) and nitrous oxide (N2O), will cause the global mean surface air temperature to rise by 2◦C by 2100 if the goals outlined in the Paris Agreement are not met (IPCC, 2018)
We explored the interacting effects of two opposing abiotic forcing factors on stomatal regulation of a tropical forage species grown in the field
Summary
Anthropogenic activities have increased atmospheric carbon dioxide concentrations ([CO2]) from 270 μmol mol−1 to the more than 400 μmol mol−1 we see today (IPCC, 2018). [CO2] is expected to reach 600 μmol mol−1 by 2050 as modeled by the Representative Concentration Pathways (RCP; IPCC, 2018). Because temperature and CO2 are important factors affecting plant physiological performance and stomatal control, understanding the impact of eCO2 and warming on plant performance and stomatal functioning in tropical pastures is vital to understanding the effect of climate change on the productivity of pastures in tropical and subtropical regions (Asner et al, 2004; Tubiello et al, 2007; Prado et al, 2016; Rojas-Downing et al, 2017)
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