[Root morphological changes in maize and soybean intercropping system under different phosphorus levels].

A pot experiment was conducted to investigate the changes of root morphology and its relationship with P uptake under different P levels (0, 50 and 100 mg P2O5·kg-1, represented by P0, P50 and P100, respectively). The results showed that intercropping significantly changed root morphological parameters of both maize and soybean, and increased the root:shoot ratio in soybean under different P levels. Intercropping significantly increased root length, root surface area, root volume, and root dry weight of maize and soybean by 25.6%, 22.0%, 39.2%, 34.3% and 28.1%, 29.7%, 37.3%, 62.3%, respectively, but significantly decreased the average root diameter by 15.2% and 11.7% compared to corresponding monoculture. The phosphorus uptake equivalent ratio (LERP) was >1, showing P uptake advantage of intercropping and that the LERP were unaffected by P levels. The root morphological changes induced by intercropping were closely related to P uptake improvement. The increases of maize root surface area and soybean root length were the main mechanisms driving efficient P uptake in maize and soybean intercropping. Based on the regression equation, 10% increase of maize root surface area or soybean root length caused 5%-10% increase of phosphorus uptake. P uptake of intercropped maize was not declined under P50 level compared to that of monoculture supplied with P100 level. In conclusion, maize and soybean intercropping has the potential to maintain crop P uptake when reducing application of phosphate fertilizer.本研究通过盆栽试验,探讨不同磷水平(0、50、100 mg P2O5·kg-1,分别用P0、P50、P100表示)下玉米与大豆间作系统根系形态的变化及其与磷吸收的关系,以明确玉米-大豆间作系统促进磷吸收的作用机制。结果表明: 不同磷水平下,间作显著改变了玉米和大豆的根系形态参数,提高了大豆根冠比。与单作模式相比,间作使玉米和大豆的根长、根表面积、根体积、根系干重分别显著增加25.6%、22.0%、39.2%、34.3%和28.1%、29.7%、37.3%、62.3%,而平均根直径分别显著降低15.2%和11.7%。不同磷水平下,磷素吸收当量比(LERP)>1,玉米-大豆间作具有明显的磷吸收优势,且LERP不受磷水平调控。间作诱导根系形态改变与磷吸收增加密切相关,其中玉米根系表面积增大、大豆根系长度增加是驱动玉米-大豆间作系统磷高效吸收的主要机制。根据回归方程,玉米根表面积和大豆根系长度增大10%,磷吸收量提高5%～10%。因此,与中等施磷水平(P100)下的单作相比,玉米-大豆间作条件下磷肥减施1/2(P50)并未降低玉米的磷吸收量。综上,玉米-大豆间作体系在减施磷肥条件下具有维持作物磷吸收的潜力。.