The available carbon (C) to phosphorus (P) ratio in the soil is regulated by extracellular hydrolases for C and P acquisition by microbes and plants. However, the stoichiometric relationship between acquiring C and P in paddy rhizosphere and bulk soils remains unclear. The objective was to explore the underlying mechanisms of C and P acquisition stoichiometry in rhizosphere and bulk soils in response to P fertilization and cellulose addition. Amendment with either cellulose or P separately caused a significant increase in the maximal velocity (V_max) of C acquisition enzymes (β-1,4-glucosidase and β-cellobiohydrolase) but decreased that of P acquisition enzymes (acid and alkaline phosphomonoesterases) in bulk soil. In contrast, lower V_max values of C and P acquisition enzymes were observed in rhizosphere soil than in bulk soil. The co-application of cellulose and P increased the V_max of P acquisition enzymes in rhizosphere soil but decreased that of only alkaline phosphomonoesterase in bulk soil. Results show that P availability and labile-C content co-regulated the P/C acquisition ratio, and two inverse linear relationships were observed. Specifically, the P/C acquisition ratio was negatively related to both the dissolved organic C/Olsen-P ratio and the microbial biomass C/P ratio in rhizosphere soil. However, the P/C acquisition ratio was positively related to both the dissolved organic C/Olsen-P ratio and the microbial biomass C/P ratio in bulk soil. Overall, microbes mineralized less organic P to acquire P in paddy soil rhizosphere (i.e., containing higher labile-C) than in bulk soil (i.e., having lower labile-C contents).

中文翻译：

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化学计量理论影响水稻散装土壤中的酶动力学，但不影响根际土壤

土壤中的有效碳 (C) 与磷 (P) 的比率受细胞外水解酶调节，用于微生物和植物获取 C 和 P。然而，在水稻根际和大块土壤中获取 C 和 P 之间的化学计量关系仍不清楚。目的是探索根际和大块土壤中 C 和 P 获取化学计量的潜在机制，以响应 P 施肥和纤维素添加。分别用纤维素或 P 进行修正导致C 获取酶（β-1,4-葡糖苷酶和 β-纤维二糖水解酶）的最大速度 ( V _max ) 显着增加，但降低了 P 获取酶（酸性和碱性磷酸单酯酶）的最大速度 (V max )。大块土壤。相比之下，较低的V _max在根际土壤中观察到 C 和 P 获取酶的值高于在块状土壤中。纤维素和P的共同应用增加了V _max根际土壤中磷获取酶的含量降低，而块状土壤中仅碱性磷酸单酯酶的含量降低。结果表明，磷的有效性和不稳定的碳含量共同调节了磷/碳的获得率，并观察到了两个反线性关系。具体而言，P/C 获取率与根际土壤中溶解有机 C/Olsen-P 比和微生物生物量 C/P 比均呈负相关。然而，P/C 获取率与块状土壤中溶解有机 C/Olsen-P 比和微生物生物量 C/P 比均呈正相关。总体而言，与大块土壤（即具有较低的不稳定碳含量）相比，微生物在稻田土壤根际（即含有较高的不稳定碳）中矿化较少的有机磷以获得磷。