The effects of Fe₃O₄ nanoparticles (NPs) and Rhizobium inoculation on nodulation, nitrogen fixation and plant growth of common bean (cv. Red Guama, Phaseolus vulgaris) plants were investigated in growth chambers. Plants were exposed to: Fe₃O₄ NPs (2000 mg/L) (T1), Rhizobium inoculation (T2) and Fe₃O₄ NPs + Rhizobium inoculation (T3); non-treated plants were considered as controls. Harvested 35-day-old treated plants showed improved symbiotic performance including increased nitrogenase activity (51.2–90.7%), nodule leghaemoglobin (44.8–80.9%) and iron content (83.4–84.2%), number of active nodules per plant (58.7–122%) and nodule dry weight (40.2–70.6%). This resulted in enhanced symbiotic nitrogen fixation,and increased shoot (26.5–50.2%) and root (24.1–48.2%) total nitrogen content in treated plants in comparison with the controls. The best result was obtained using treatment T3. Furthermore, Fe₃O₄ NPs were taken up by bean plants in treatments T1 and T3, and these accumulated in their organs, including in nodules. All treatments led to an increase in root (51.9–79.8%) and shoot (27.5–52.7%) lengths, in leaf area (10.9–16.8%) and in root (10.1–17.8%), stem (9.8–12.7%) and leaf dry weight (8–17.3%) compared to control plants. Thus applied treatments have the potential to improve common bean plant growth through enhancement of nodulation and nitrogen fixation during vegetative growth.This study also provides strong evidence that the presence Fe₃O₄ NPs in nodules improves the symbiotic performance between Rhizobium (leguminosarum CF1 strain) and the common bean plant, due to enhanced nodulation and nitrogen fixation.

在生长室中研究了Fe ₃ O ₄纳米颗粒（NPs）和根瘤菌接种对普通豆（cv。Red Guama，菜豆）的结瘤，固氮和植物生长的影响。植物暴露于：Fe ₃ O ₄ NPs（2000 mg / L）（T1），根瘤菌接种（T2）和Fe ₃ O ₄ NPs + 根瘤菌接种（T3）；未处理的植物被认为是对照。收获的经过35天龄处理的植物表现出更好的共生性能，包括增加的固氮酶活性（51.2–90.7％），根瘤性血红蛋白（44.8–80.9％）和铁含量（83.4–84.2％），每棵植物的活动结节数（58.7– 122％）和结节干重（40.2–70.6％）。与对照相比，这提高了处理植物的共生固氮能力，并增加了芽（26.5–50.2％）和根（24.1–48.2％）的总氮含量。使用处理T3可获得最佳结果。此外，Fe ₃ O ₄在处理T1和T3中，豆类植物吸收了NP，这些NP积累在其器官中，包括结核中。所有处理均导致根长增加（51.9–79.8％）和枝条长（27.5–52.7％），叶面积（10.9–16.8％）和根（10.1–17.8％），茎（9.8–12.7％）增加与对照植物相比，其叶干重（8–17.3％）。因此，所应用的处理方法有可能通过营养生长过程中的结瘤和固氮作用来改善普通豆类植物的生长。这项研究还提供了强有力的证据，表明结核中Fe ₃ O ₄ NP的存在改善了根瘤菌（豆科植物CF1菌株）之间的共生性能。和普通豆类植物，因为其结瘤和固氮能力增强。