Suaeda fruticosa and S. monoica are important halophytes for ecological rehabilitation of saline lands. We report differential physio-chemical, photosynthetic, and chlorophyll fluorescence responses in these halophytes under 100 mM sodium chloride (NaCl), 50% strength (16.25 ppt) of seawater (SW)-imposed salinity, and 10% polyethylene glycol 6000 imposed osmotic stress at 380 (ambient) and 1200 (elevated) µmol mol^–1 CO₂ concentrations. SW salinity enhanced the growth in both species; however, compared with S. fruticosa, the S. monoica exhibited comparatively better growth and biomass accumulation under saline conditions at elevated CO₂. Results demonstrated better photosynthetic performances of S. monoica under stress conditions at both levels of CO₂, and this resulted in higher accumulation of carbon, nitrogen, sugar, and starch contents. S. monoica exhibited improved antenna size, electron transfer at PSII donor side, and efficient working of photosynthetic machinery at elevated CO₂, which might be due to efficient upstream utilization of reducing power to fix the CO₂. The δ¹³C results supported the operation of C₄ CO₂ fixation in S. monoica and C₃ or intermediate pathway of CO₂ fixation in S. fruticosa. Lower accumulation of reactive oxygen species, reduced membrane damage, lowered solute potential, and higher accumulation of proline and polyphenol contents indicated elevated CO₂-induced abiotic stress tolerance in Suaeda. Higher activity of antioxidant enzymes in both species at both levels of CO₂ help plants to combat the oxidative stress. Upregulation of NADP-dependent malic enzyme and NADP-dependent malate dehydrogenase genes indicated their role in abiotic stress tolerance as well as photosynthetic carbon (C) sequestration. Operation of C₄ type CO₂ fixation in S. monoica and an intermediate CO₂ fixation in S. fruticosa could be the possible reason for the superior photosynthetic efficiency of S. monoica under stress conditions at elevated CO₂.

Suaeda fruticosa和S. monoica是盐渍地生态修复的重要盐生植物。我们报告了这些盐生植物在 100 mM 氯化钠 (NaCl)、50% 强度 (16.25 ppt) 海水 (SW) 施加的盐度和 10% 聚乙二醇 6000 施加的渗透胁迫下的不同理化、光合和叶绿素荧光响应在 380（环境）和 1200（升高）μmol mol ^–1 CO ₂浓度下。西南盐度促进了两个物种的生长；然而，较S.紫穗槐，所述S.同丝水霉在升高的CO表现出盐水的条件下比较更好的生长和生物量积累₂. 结果表明，在两种 CO ₂水平的胁迫条件下，S. monoica 的光合性能更好，这导致碳、氮、糖和淀粉含量的积累更高。S. monoica表现出改进的天线尺寸、PSII 供体侧的电子转移以及光合作用机械在升高的 CO _{2 下的}有效工作，这可能是由于上游有效利用还原力来固定 CO ₂。δ ¹³ C 结果支持了在S. monoica和 C _{3 中}固定C ₄ CO ₂的操作或 CO _{2 的}中间途径固定在S. fruticosa 中。活性氧物质的较低积累、膜损伤减少、溶质电位降低以及脯氨酸和多酚含量的较高积累表明Suaeda提高了 CO ₂诱导的非生物胁迫耐受性。在两个 CO ₂水平下，两个物种中抗氧化酶的更高活性有助于植物对抗氧化应激。的上调NADP依赖性苹果酸酶和NADP依赖性苹果酸脱氢酶的基因在非生物胁迫耐受性以及光合碳（C）表示螯合的作用。C ₄型 CO ₂固定在S. monoica 中的操作S. fruticosa 中的中间 CO ₂固定可能是S. monoica在 CO ₂升高的胁迫条件下具有优异光合效率的可能原因。