不同种植密度下丛枝菌根真菌对玉米磷吸收的影响

Effect of arbuscular mycorrhizal fungi on P uptake of maize(Zea mays L.)under different growing density

【目的】利用土著丛枝菌根真菌(arbuscular mycorrhizal fungi,AM真菌)与作物形成互惠互利的共生关系提高作物对土壤磷的利用效率是解决农业生产中磷供需矛盾的主要途径之一,本研究在大田玉米不同种植密度条件下,研究AM真菌对玉米根系的侵染及磷吸收作用,为揭示集约化玉米高效获取磷的机理提供理论依据。【方法】以大田作物玉米的两种种植密度(5×104plants/hm2和9×104plants/hm2)体系为研究对象,在田间原位埋设PVC管装置,通过测定菌丝生长室中的菌丝密度和有效磷耗竭来确定不同种植密度体系条件下AM真菌对玉米磷吸收的作用。【结果】相对于低密度种植群体,高密度群体显著降低了玉米拔节期土壤有效磷的耗竭量,同时增加了玉米地上部的磷含量,即磷吸收效率,增幅达20%;在玉米拔节期,增加种植密度使根际的根外菌丝生物量(菌丝密度)降低了4%,而非根际土壤中的根外菌丝生物量(菌丝密度)增加了37%;高密度玉米种植密度群体中AM真菌的根外菌丝对土壤有效磷耗竭的贡献增加了22%。【结论】集约化玉米生产中土著AM真菌依然帮助植株从土壤中吸收有效磷;高密度体系下玉米对磷的吸收更加依赖于AM真菌。高密度种植增加AM真菌对玉米的侵染、根外菌丝量和对土壤有效磷的吸收。

【Objectives】Improving soil P utilization efficiency for crop by using arbuscular mycorrhizal symbiosis is one of effective ways to solve contradiction between supply and demand of phosphorus resource in the crop production. However,studies on mycorrhizal colonization and phosphorus uptake of maize with different growing density in field have been less concerned.【Methods】A field experiment was conducted with two planting densities（ 5 ×104plants / hm2 and 9 × 104 plants / hm2） of maize（ Zea mays L.）. PVC pipes were inserted around maize roots,and phosphorus depletion and hyphae length density of soil in the PVC compartment were determined to test effects of arbuscular mycorrhizal fungi on phosphorus uptake of maize. 【Results】At the V6 stage,the Olsen-P depletion was significantly reduced when the planting density was increased,while the increment of the shoot P content（ P absorption efficiency） was up to 20%. With the increase of the planting density,the extraradical hyphae length density in the rhizosphere was decreased by 4% at the V6 stage,while the hyphae density in the bulk soil was increased by 37%. The contribution of extraradical hyphae to Olsen-P depletion was significantly increased by 22%under the higher planting density condition. 【Conclusions 】These results indicated that P uptake of maize was dependent on AM symbiosis when the planting density was increased,because of the mycorrhizal colonization,extraradical hyphae density and P uptake were significantly enhanced,comparing to the low planting density.