Diurnal and Seasonal Variations in the Photosynthetic Characteristics and the Gas Exchange Simulations of Two Rice Cultivars Grown at Ambient and Elevated CO2

Abstract

Investigating the diurnal and seasonal variations of plant photosynthetic performance under future atmospheric CO2 conditions is essential for understanding plant adaptation to global change and for estimating parameters of ecophysiological models. In this study, diurnal changes of net photosynthetic rate (Anet), stomatal conductance (gs), and photochemical efficiency of PSII (Fv′/Fm′) were measured in two rice cultivars grown in the open-top-chambers at ambient (∼450 μmol mol–1) and elevated (∼650 μmol mol–1) CO2 concentration [(CO2)] throughout the growing season for 2 years. The results showed that elevated (CO2) greatly increased Anet, especially at jointing stage. This stimulation was acclimated with the advance of growing season and was not affected by either stomatal limitations or Rubisco activity. Model parameters in photosynthesis model (Vcmax, Jmax, and Rd) and two stomatal conductance models (m and g1) varied across growing stages and m and g1 also varied across (CO2) treatments and cultivars, which led to more accurate photosynthesis and stomatal conductance simulations when using these cultivar-, CO2-, and stage- specific parameters. The results in the study suggested that further research is still needed to investigate the dominant factors contributing to the acclimation of photosynthetic capacity under future elevated CO2 conditions. The study also highlighted the need of investigating the impact of other environmental, such as nitrogen and O3, and non-environmental factors, such as additional rice cultivars, on the variations of these parameters in photosynthesis and stomatal conductance models and their further impacts on simulations in large scale carbon and water cycles.

Yield potentiality and photosynthetic parameters of some local and exotic elite rice genotypes

“…Meanwhile, significant mean squares due to the interaction between genotypes and seasons were significant for all studied traits indicated that genotypes behaved differently in both summer growing seasons. These results are in line with those obtained by several investigators [6,8,9,10,11,24,25,26,27].…”

Quantitative effects of environmental variation on stomatal anatomy and gas exchange in a grass model

“…Despite the consistent stomatal responsiveness in B. distachyon, we observed a significant influence of the time of the day on light-response stomatal kinetics. While diurnal variation on gas exchange has been well described for C 3 species (de Dios, 2017; Matthews et al, 2017;Miao et al, 2021;Roussel et al, 2009;Stangl et al, 2019;Vahisalu et al, 2008), the observed diurnal variation on stomatal responsiveness to changing light in the tightly regulated conditions of the IRGA chambers was compelling. Stomatal closure and opening speed were mainly affected by the time of the day and by steady-state g sw prior and/or after the change in light intensity.…”

Quantitative effects of environmental variation on stomatal anatomy and gas exchange in a grass model

“…Despite the consistent stomatal responsiveness in B. distachyon , we observed a significant influence of the time of the day on light-response stomatal kinetics. While diurnal variation on gas exchange has been well described for C 3 species (Matthews et al, 2017; Miao et al, 2021; Resco de Dios, 2017; Roussel et al, 2009; Stangl et al, 2019; Vahisalu et al, 2008), the observed diurnal variation on stomatal responsiveness to changing light in the tightly regulated conditions of the IRGA chambers was compelling. Stomatal closure and opening speed were mainly affected by the time of the day and by steady-state g sw prior and/or after the change in light intensity.…”