Aims

Sugars in soils play vital roles in soil aggregation and microbial activity, which is easily affected by environmental factors. Here, we investigated the accumulation of total sugars and monosaccharides in the rhizosphere soil of black locust seedlings exposed to the contamination of elevated atmospheric CO₂ (eCO₂) and cadmium (Cd) and its driving factors.

Results

Under eCO₂ + Cd compared to Cd, glucose, galactose, arabinose, mannose, and xylose concentrations in the rhizosphere soil increased and the increases were significant at 4.5 mg Cd kg⁻¹ (p < 0.05). Glucose was the most abundant sugar. The GM/AX ratio increased (p < 0.05) under eCO₂ + Cd relative to Cd, suggesting that sugars in rhizosphere soils might be mainly from microbial synthesis under eCO₂ + Cd. In addition, CO₂, Cd, and CO₂ + Cd influenced (p < 0.05) total sugar and monosaccharide concentrations and the (galactose + mannose)/(arabinose + xylose) (GM/AX) ratio. Sugars concentrations in rhizosphere soils were affected (p < 0.05) by responses of leaf and root biomass, Cd in roots, S in leaves, leaf C/N ratio, and pH and C in rhizosphere soils to eCO₂. However, the contribution of sugars in the roots to those in rhizosphere soils was not significant under elevated CO₂ + Cd exposure.

Conclusions

Elevated CO₂ stimulated sugar concentrations in the rhizosphere soil of black locusts exposed to Cd, which was helpful to understand the contribution of global change scenarios to sugar accumulation in the rhizosphere of plants grown in heavy metal-contaminated soils.

中文翻译：

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大气CO2升高普遍提高了镉暴露下刺槐幼苗根际土壤中的可溶性糖含量

宗旨

土壤中的糖类在土壤团聚和微生物活动中起着至关重要的作用，容易受到环境因素的影响。在这里，我们调查了暴露于大气 CO ₂ (eCO ₂ ) 和镉 (Cd)污染的刺槐幼苗根际土壤中总糖和单糖的积累及其驱动因素。

结果

在eCO ₂  + Cd 下，与Cd 相比，根际土壤中葡萄糖、半乳糖、阿拉伯糖、甘露糖和木糖的浓度增加，并且在4.5 mg Cd kg ^{-1 时}增加显着（p  < 0.05）。葡萄糖是最丰富的糖。GM/AX 比率 在eCO ₂  + Cd下相对于Cd增加（p < 0.05），表明根际土壤中的糖可能主要来自eCO ₂  + Cd下的微生物合成。此外，CO ₂、Cd 和 CO ₂  + Cd 影响（p < 0.05) 总糖和单糖浓度以及（半乳糖 + 甘露糖）/（阿拉伯糖 + 木糖）（GM/AX）比率。根际土壤中的糖浓度受 叶和根生物量、根中 Cd、叶中 S、叶 C/N 比以及根际土壤中的 pH 和 C 对 eCO ₂的响应的影响 ( p < 0.05) 。然而，在升高的CO ₂  + Cd 暴露下，根中的糖对根际土壤中的糖的贡献不显着。

结论

升高的CO ₂刺激了暴露于Cd 的黑蝗的根际土壤中的糖浓度，这有助于了解全球变化情景对重金属污染土壤中生长的植物根际糖积累的贡献。