Photosynthetic light response curves were measured in four cultivars of Humulus lupulus L. (hop) at CO₂ concentrations of 415, 500, 600, and 700 μmol CO₂ mol⁻¹. Short-term elevated CO₂ increased net photosynthesis (A_n), light-saturated rates of photosynthesis, and quantum yield and decreased the light compensation point and leaf respiration. To illustrate the effects on canopy carbon gain, we used a rigorously validated physiologically-explicit canopy process model (MAESTRA). The cultivar-specific leaf-level physiological response parameters at 415, 500, 600, and 700 μmol CO₂ mol⁻¹ were extrapolated throughout the canopy to reproduce the cultivar-specific carbon gain under current and future atmospheric CO₂ conditions. Under sub optimal light conditions, the initial CO₂ increase of 415 to 500 μmol CO₂ mol⁻¹ resulted in the highest relative carbon gain increase (∼18%), whereas enrichment from 500 to 600 and 600 to 700 μmol CO₂ mol⁻¹ resulted in an additional carbon uptake of ∼16% and ∼12%. Ratios of A_n to increased CO₂ indicated that shaded leaves benefit more from elevated CO₂ than light saturated leaves. Estimated daily canopy carbon uptake increased ∼24% from 415 to 500 µmol mol⁻¹ CO₂. Daily carbon uptake increased by ∼17% from 500 to 600 µmol mol⁻¹ CO₂ and ∼18% from 600 to 700 µmol mol⁻¹. Thus, in comparison to leaves exposed to direct sunlight, hop canopy carbon gain in shaded diffuse light lower canopy layers may contribute a greater proportion of total canopy carbon in future atmospheric CO₂ conditions.

在415、500、600和 700 μmol CO ₂ mol ^{-1 的}CO ₂浓度下，在四个Humulus lupulus L.（啤酒花）栽培品种中测量了光合光响应曲线。短期升高的 CO ₂增加了净光合作用 (A _n )、光合作用的光饱和速率和量子产量，并降低了光补偿点和叶片呼吸。为了说明对冠层碳增加的影响，我们使用了经过严格验证的生理显式冠层过程模型 (MAESTRA)。在 415、500、600 和 700 μmol CO ₂ mol ^{-1 下}的品种特异性叶片水平生理反应参数外推整个冠层，以重现当前和未来大气 CO ₂条件下品种特定的碳增益。在次优光照条件下，初始 CO ₂增加 415 至 500 μmol CO ₂ mol ^-1导致最高的相对碳增益增加（~18%），而富集从 500 至 600 和 600 至 700 μmol CO ₂ mol ^{- 1}导致额外的碳吸收~16%和~12%。A _n与增加的 CO _{2 的}比率表明，与光饱和的叶子相比，阴影叶从升高的 CO _{2 中}获益更多。估计的每日冠层碳吸收量从 415 到 500 µmol mol 增加了约 24%^-1 CO ₂。每日碳吸收量从 500 到 600 µmol mol ^-1 CO ₂增加了约 17%，从 600 到 700 µmol mol ^-1增加了约18% 。因此，与暴露在阳光直射下的叶子相比，在阴影漫射光下的树冠层中啤酒花冠层碳的增加可能在未来大气 CO ₂条件下占总冠层碳的比例更大。