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CO2 refixation is higher in leaves of woody species with high mesophyll and stomatal resistances to CO2 diffusion
Tree Physiology ( IF 4 ) Pub Date : 2021-02-17 , DOI: 10.1093/treephys/tpab016
Diana Eckert 1 , Helle Juel Martens 2 , Lianhong Gu 3 , Anna Monrad Jensen 1
Affiliation  

The percentage of respiratory and photorespiratory CO2 refixed in leaves (Pr) represents part of the CO2 used in photosynthesis. The importance of Pr as well as differences between species and functional types are still not well investigated. In this study, we examine how Pr differs between six temperate and boreal woody species: Betula pendula, Quercus robur, Larix decidua, Pinus sylvestris, Picea abies, and Vaccinium vitis-idaea. The study covers early and late successional species, deciduous broadleaves, deciduous conifers, evergreen conifers, and evergreen broadleaves. We investigated whether some species or functional types had higher refixation percentages than others, whether leaf traits could predict higher Pr, and whether these traits and their impact on Pr changed during growing seasons. A/Ci-curves, measured early, mid and late season, were used to estimate and compare Pr, mesophyll resistance (rm), and stomatal resistance (rs) to CO2 diffusion. Additionally, light images and transmission electron microscope images were used to approximate the fraction of intercellular airspace and cell wall thickness. We found that evergreens, especially late successional species, refixed a significantly higher amount of CO2 than the other species throughout the entire growing season. In addition, rm, rs and leaf mass per area, traits that typically are higher in evergreen species, were also significantly, positively correlated with Pr. We suggest that this is due to higher rm decreasing diffusion of (photo) respiratory CO2 out of the leaf. Cell wall thickness had a positive effect on Pr and rm, while the fraction of intercellular airspace had no effect. Both were significantly different between evergreen conifers and other types. Our findings suggest that species with a higher rm use a greater fraction of mitochondria-derived CO2, especially when stomatal conductance is low. This should be taken into account when modeling the overall CO2 fertilization effect for terrestrial ecosystems dominated by high-rm species.

中文翻译:

叶肉和气孔对 CO2 扩散具有高抗性的木本植物的叶子中的 CO2 再固定更高

重新固定在叶子中的呼吸和光呼吸 CO 2的百分比( P r ) 代表用于光合作用的部分 CO 2P r的重要性以及物种和功能类型之间的差异仍未得到很好的研究。在这项研究中,我们研究了6 种温带和北方木本植物之间P r 的差异:桦木栎属植物落叶松樟子松冷杉牛痘. 该研究涵盖了早期和晚期演替物种、落叶阔叶树、落叶针叶树、常绿针叶树和常绿阔叶树。我们调查了某些物种或功能类型是否比其他物种或功能类型具有更高的再固定百分比,叶片性状是否可以预测更高的P r,以及这些性状及其对P r的影响是否在生长季节发生变化。使用早、中和晚季节测量的 A/Ci 曲线来估计和比较P r、叶肉抗性 ( r m ) 和气孔抗性 ( r s ) 对 CO 2扩散。此外,使用光图像和透射电子显微镜图像来近似细胞间隙和细胞壁厚度的分数。我们发现,在整个生长季节,常绿植物,尤其是晚期演替物种,重新固定的 CO 2量明显高于其他物种。此外,r mr s和单位面积叶片质量(常绿物种中通常较高的性状)也与P r显着正相关。我们认为这是由于较高的r m减少了(照片)呼吸 CO 2 的扩散从叶子里出来。细胞壁厚度对P rr m有积极影响,而细胞间隙的比例没有影响。两者在常绿针叶树和其他类型之间都有显着差异。我们的研究结果表明,具有较高r m 的物种使用更多比例的线粒体衍生的 CO 2,尤其是当气孔导度较低时。这应该建模总体CO时,可以考虑到2用于通过高主导陆地生态系统施肥效果- [R品种。
更新日期:2021-02-17
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