Abstract The present work aimed to isolate plant growth-promoting bacteria from forest soil and to study their effect on the development of Pinus oocarpa. Strain C2 was selected from 35 isolated soil bacteria for its high phosphate solubilization index (2.40) in solid media. Its ability to solubilize different sources of phosphate (calcium, aluminum, or iron) was studied in liquid medium at different pH, 5 and 7. Maximum P released was 118.44 mg/L (tricalcium phosphate). Strain C2 was also able to produce up to 45 mg/L of indoleacetic acid-homologous compounds (IAAs) at different initial pH, glucose, and tryptophan (as IAAs precursor) concentration. Strain C2 was identified as Enterobacter hormaechei subsp. xiangfangensis and was periodically inoculated on P. oocarpa seedlings during 180 days (nursery stage, double-transplanting system). It was observed that the mineral content in P. oocarpa inoculated with E. hormaechei (strain C2) increased, especially nitrogen in roots and phosphorus in stems. The Dickson quality index (DQI) of inoculated plants was higher in comparison with the control ones.

中文翻译：

---

从森林土壤中分离的具有植物生长促进活性的细菌对松树幼苗的磷酸盐增溶和吲哚类化合物的产生

摘要 目前的工作旨在从森林土壤中分离出植物促生长菌，并研究它们对松果生长的影响。菌株 C2 是从 35 种分离的土壤细菌中挑选出来的，因为它在固体培养基中具有高磷酸盐溶解指数 (2.40)。在不同 pH 值、5 和 7 的液体介质中研究了其溶解不同来源的磷酸盐（钙、铝或铁）的能力。释放的最大 P 为 118.44 mg/L（磷酸三钙）。在不同的初始 pH、葡萄糖和色氨酸（作为 IAA 前体）浓度下，菌株 C2 还能够产生高达 45 mg/L 的吲哚乙酸同源化合物 (IAA)。菌株 C2 被鉴定为 Enterobacter hormaechei subsp。在 180 天期间（苗圃阶段，双移系统）定期接种香芳树幼苗。据观察，接种 E. hormaechei（菌株 C2）的 P. oocarpa 的矿物质含量增加，尤其是根中的氮和茎中的磷。接种植株的 Dickson 质量指数 (DQI) 高于对照植株。