Background and aims

Cereal/legume intercropping can enhance phosphorus (P) uptake compared with monocultures. However, the mechanisms through which arbuscular mycorrhizal fungi (AMF) and phosphate solubilizing bacteria (PSB) contribute to the advantages in biomass and P uptake by cereal/legume intercropping remain elusive.

Methods

We first analyzed P cycling-related soil microbiome and the associated genes in a long-term low P (LP) and high P (HP) input field experiment. Then we conducted two mesocosm experiments by establishing with two root compartments with the planting patterns of maize monoculture and maize/faba bean intercropping. One compartment of monocultured maize and intercropped faba bean was inoculated with AMF (donor), and the suspensions of LP or HP soils or water was added to the other compartment (receiver) in experiment I to test the legacy effect of soil microbiome conditioned by different field P fertilization, and the following experiment was to detect the effect of specific organic or inorganic PSB on intercropping interactions and advantages.

Main results

The abundance and structure of total P cycling-related microbes and genes were comparable between LP and HP soils. The addition of bacterial suspensions significantly enhanced shoot biomass but not P content of receiver maize regardless of the AMF presence or not. With AMF, single inorganic PSB and the mixed inorganic and organic PSB increased the shoot biomass and P content of receiver maize than single organic PSB regardless of monocultured or intercropped receiver maize. However, only the mixed inorganic and organic PSB established intercropping advantages in shoot biomass and P content of receiver maize.

Conclusion

The hyphae from faba bean stimulate the cooperation between organic and inorganic PSB to improve the growth and P content of maize in maize/faba bean mixture. Our study emphasized that maintaining the diversity of AMF and PSB communities in soil is important for the overyielding and P uptake by intercropping.

中文翻译：

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增磷细菌而不是丛枝菌根真菌推动玉米/蚕豆间作的优势

 背景和目标

与单一栽培相比，谷物/豆类间作可以提高磷 （P） 的吸收。然而，丛枝菌根真菌 （AMF） 和磷酸盐溶解菌 （PSB） 通过谷物/豆类间作促进生物量和 P 吸收优势的机制仍然难以捉摸。

 方法

我们首先在长期低 P （LP） 和高 P （HP） 输入田间试验中分析了 P 循环相关的土壤微生物组和相关基因。然后，我们进行了两个中宇宙实验，建立了玉米单作和玉米/蚕豆间作的种植模式的两个根室。在实验 I 中，用 AMF（供体）接种单作玉米和间作蚕豆的一个隔室，并将 LP 或 HP 土壤或水的悬浮液添加到另一个隔室（接收器）中，以测试受不同田地 P 施肥条件的土壤微生物组的遗留效应，接下来的实验是检测特定有机或无机 PSB 对间作相互作用和优势的影响。

 主要结果

LP 和 HP 土壤中总磷循环相关微生物和基因的丰度和结构相当。无论是否存在 AMF，添加细菌悬浮液都会显著提高接收玉米的地上部生物量，但不提高 P 含量。使用 AMF，无论单作还是间作接收玉米，单一无机PSB和无机有机混合PSB都比单一有机PSB增加了接收玉米的地上部生物量和P含量。然而，只有无机和有机混合 PSB 在接收玉米地上部生物量和 P 含量方面建立了间作优势。

 结论

蚕豆菌丝刺激有机和无机 PSB 之间的合作，以提高玉米/蚕豆混合物中玉米的生长和 P 含量。我们的研究强调，保持土壤中 AMF 和 PSB 群落的多样性对于间作的超产量和 P 吸收很重要。