不同土壤施磷和接种根瘤菌对大豆||玉米间作系统氮磷吸收的影响

Effects of phosphorus application and rhizobial inoculation on nitrogen and phosphorus uptake in soybean||maize intercropping systems in different soil types

通过在酸性与石灰性土壤进行大豆[Glycine max(L.)Merr.]||玉米(Zea mays L.)间作接种根瘤菌的盆栽试验,对比不同土壤类型不同施磷条件下根瘤菌接种对间作大豆、玉米的生长、氮磷吸收和根际理化性质的影响,为根瘤菌剂的田间应用提供参考。本试验以‘巴西十号’大豆品种和‘正甜68’玉米品种为试验材料,采用三因素试验设计:A因素为磷水平[施磷肥(+P)和不施磷肥(–P)];B因素为两类土壤[酸性(宁西和翁源土壤)土壤与石灰性(三坪和昌平土壤)土壤];C因素为两种接种处理[接种(+Ri)与不接种根瘤菌(–Ri)],大豆结荚期测定间作大豆根瘤性状以及间作大豆和玉米的植株干重、植株总吸氮/磷量与相关根际指标。结果表明,酸性土壤施磷条件下接种根瘤菌显著增加了间作大豆的总吸氮量;石灰性土壤无论是否施用磷,接种根瘤菌均改善了间作大豆的根瘤性状,增加了总吸氮量;并且石灰性土壤接种根瘤菌能够促进间作大豆磷吸收。两地的石灰性土壤接种根瘤菌后大豆植株总吸磷量显著增加,三坪石灰性土壤施磷条件下接种根瘤菌后大豆根际pH显著降低,根际酸性磷酸酶活性显著增加;昌平石灰性土壤施磷条件下接种根瘤菌后大豆及其间作玉米根际碱性磷酸酶活性均显著增加。石灰性土壤在间作大豆植株总吸氮/磷量增加的基础上,接种根瘤菌增加了植株干重;然而,接种根瘤菌对间作玉米植株干重和总吸氮/磷量的促进作用并不明显。综上,土壤pH和磷有效性显著影响根瘤菌接种的效果。酸性土壤施磷条件下接种根瘤菌增加了间作大豆的总吸氮量,石灰性土壤接种根瘤菌能够达到氮磷协同高效促进间作大豆的生长。石灰性土壤接种根瘤菌促进磷活化吸收主要是由于增强了间作大豆的根际过程。

A pot experiment was conducted to compare the effects of rhizobial inoculation on growth,nitrogen(N)and phosphorus(P)uptake,and rhizosphere chemical properties of soybean[Glycine max(L.)Merr.]and maize(Zea mays L.)intercropping systems with different P fertilizer applications in both acidic and calcareous soils,to provide a reference for the field application of rhizobial inoculants.The pot experiment with‘BX10’soybean variety and‘Zhengtian 68’maize variety as experimental materials adopted a three-factor experimental design,including factor A,P levels[with P fertilizer(+P)and without P fertilizer(–P)];factor B,two soil pH types(acid soils form Ningxi and Wengyuan,and calcareous soils form Sanping and Changping);and factor C,two inoculation treatments[with rhizobial inoculation(+Ri)or without rhizobial inoculation(–Ri)].The nodule traits of soybean,plant dry weight,total N and P uptake,and related rhizosphere traits of soybean and maize were determined at the pod stage of soybean.The results showed that inoculation with rhizobia increased the total N uptake of the intercropped soybean under P application in acidic soil,and inoculation with rhizobia improved nodule traits and increased total N uptake of the intercropped soybean regardless of P application and promoted total P uptake of the intercropped soybean in calcareous soil.In both calcareous soils,the total P uptake of the inoculated soybean plants increased significantly.In the calcareous soil of Sanping,the rhizosphere pH was significantly reduced and the rhizosphere acid phosphatase activity of the inoculated soybean significantly increased after rhizobial inoculation and P application.In the calcareous soil of Changping,the rhizosphere alkaline phosphatase activities of intercropped soybean and maize significantly increased after inoculation with rhizobia under P application.With increased total N and P uptake,rhizobial inoculation increased the plant dry weight of intercropped soybean in calcareous soil but had no effect on plant dry weight and total N and P uptake of intercropped maize.In conclusion,soil pH and P availability significantly influenced the effectiveness of rhizobial inoculation.In acidic soil,inoculation with rhizobia increased the total N uptake of intercropped soybean under P application.In calcareous soil,inoculation with rhizobia could promote the synergistic effects of N and P and further promote the growth of intercropped soybean.The promotion of P mobilization and acquisition by rhizobial inoculation might be attributed to the enhancement of rhizosphere processes in calcareous soil.