The commercially important red macroalga Pyropia (formerly Porphyra) yezoensis is, in its natural intertidal environment, subjected to high levels of both photosynthetically active and ultraviolet radiation (PAR and UVR, respectively). In the present work, we investigated the effects of a plausibly increased global CO₂ concentration on quantum yields of photosystems II (PSII) and I (PSI), as well as photosynthetic and growth rates of P. yezoensis grown under natural solar irradiance regimes with or without the presence of UV-A and/or UV-B. Our results showed that the high-CO₂ treatment (~1000 μbar, which also caused a drop of 0.3 pH units in the seawater) significantly increased both CO₂ assimilation rates (by 35%) and growth (by 18%), as compared with ambient air of ~400 μbar CO₂. The inhibition of growth by UV-A (by 26%) was reduced to 15% by high-CO₂ concentration, while the inhibition by UV-B remained at ~6% under both CO₂ concentrations. Homologous results were also found for the maximal relative photosynthetic electron transport rates (rETR_max), the maximum quantum yield of PSII (F_v/F_m), as well as the midday decrease in effective quantum yield of PSII (YII) and concomitant increased non-photochemical quenching (NPQ). A two-way ANOVA analysis showed an interaction between CO₂ concentration and irradiance quality, reflecting that UVR-induced inhibition of both growth and YII were alleviated under the high-CO₂ treatment. Contrary to PSII, the effective quantum yield of PSI (YI) showed higher values under high-CO₂ condition, and was not significantly affected by the presence of UVR, indicating that it was well protected from this radiation. Both the elevated CO₂ concentration and presence of UVR significantly induced UV-absorbing compounds. These results suggest that future increasing CO₂ conditions will be beneficial for photosynthesis and growth of P. yezoensis even if UVR should remain at high levels.

商业上重要的红色大藻Pyropia（原紫菜）条斑紫菜是在其天然环境潮间带，经受高水平的光合有效和紫外辐射的（分别为PAR和UVR）。在目前的工作中，我们调查了可能增加的全球CO ₂浓度对光系统II（PSII）和I（PSI）的量子产率以及在自然太阳辐照下生长的yezoensis光合速率和生长速率的影响。或不存在UV-A和/或UV-B。我们的结果表明，高CO ₂与约400μbarCO _2的环境空气相比，处理（约1000μbar，也导致海水中的pH值下降了0.3个单位）显着提高了CO ₂同化率（增加了35％）和生长（增加了18％）。。在高CO ₂浓度下，UV-A对生长的抑制作用（降低了26％）降低到15％，而在两种CO ₂浓度下，UV-B的抑制作用都保持在6％左右。对于最大相对光合电子传输速率（rETR _max），PSII的最大量子产率（F _v / F _m），也发现了同源的结果。），以及PSII（YII）的有效量子产率的午间下降和伴随的非光化学猝灭（NPQ）的增加。双向ANOVA分析显示，CO ₂浓度与辐照度质量之间存在相互作用，反映出在高CO ₂处理下，UVR诱导的生长和YII抑制均得到缓解。与PSII相反，PSI（YI）的有效量子产率在高CO ₂条件下显示出较高的值，并且不受UVR的存在显着影响，表明它受到了良好的保护，免受了这种辐射。升高的CO ₂浓度和UVR的存在均显着诱导了紫外线吸收化合物。这些结果表明，未来CO _2的增加即使UVR保持在较高水平，这些条件也将有利于夜蛾假单胞菌的光合作用和生长。