Mycorrhizal fungi are ubiquitous in agroecosystems and form symbiotic associations that contribute to the phosphorus (P) acquisition of many plants. The impact of mycorrhizas is most pronounced in P-deficient soil and commonly involves modifications to the root morphology of colonised plants. However, the consequences of mycorrhizal colonisation on root acclimation responses to P stress are not well described. Five annual pasture legumes, with differing root morphologies, were grown to determine the effect of mycorrhizal colonisation on shoot yield, root morphology and P uptake. Micro-swards of each legume were established in pots filled with a topsoil layer that had been amended with five rates of P fertiliser. The topsoil overlaid a low-P subsoil that mimicked the stratification of P that occurs under pasture. Mycorrhizal colonisation improved P acquisition and shoot yield in the low-P soil treatments, but did not reduce the critical external P requirement of the legumes for near-maximum yield. The yield responses of the mycorrhizal plants were associated with reduced dry matter allocation to topsoil roots, which meant that the P acquisition benefit associated with mycorrhizal colonisation was not additive in the P-deficient soil. The contribution of the mycorrhizal association to P acquisition was consistent among the legumes when they were compared at an equivalent level of plant P stress, and was most pronounced below a P stress index of ~0.5. The intrinsic root morphology of the legumes determined their differences in P-acquisition efficiency irrespective of mycorrhizal colonisation.

菌根真菌在农业生态系统中无处不在，并形成共生共生体，从而促进了许多植物的磷（P）的获取。菌根在缺磷土壤中的影响最为明显，通常涉及定植植物根系形态的改变。但是，菌根定殖对根系对磷胁迫的适应性反应的后果尚未得到很好的描述。种植了五种具有不同根系形态的一年生牧草豆科植物，以确定菌根定植对枝条产量，根系形态和磷吸收的影响。在充满表土层的盆中建立每种豆类的微纤维，该表层已用五种磷肥进行了改良。表土覆盖了低磷的底土，模拟了牧场下磷的分层。在低磷土壤处理中，菌根定植改善了磷的获取和枝条产量，但并没有降低豆类接近最大产量的关键外部磷需求量。菌根植物的产量响应与干物质分配到表土根部的减少有关，这意味着与菌根定殖相关的磷获取益处在缺磷的土壤中无累加。当在相同水平的植物P胁迫下比较豆科植物时，菌根协会对P摄取的贡献是一致的，并且在P胁迫指数低于〜0.5时最为明显。豆科植物的内在根系形态决定了它们在磷获取效率上的差异，而与菌根定殖无关。但是并没有降低豆类接近最大产量的临界外部磷需求量。菌根植物的产量响应与干物质分配到表土根部的减少有关，这意味着与菌根定殖相关的磷获取益处在缺磷的土壤中无累加。当在相同水平的植物P胁迫下比较豆科植物时，菌根协会对P摄取的贡献是一致的，并且在P胁迫指数低于〜0.5时最为明显。豆科植物的内在根系形态决定了它们在磷获取效率上的差异，而与菌根定殖无关。但是并没有降低豆类接近最大产量的临界外部磷需求量。菌根植物的产量响应与干物质分配到表土根部的减少有关，这意味着与菌根定植有关的磷获取益处在磷缺乏的土壤中并没有累加。当在相同水平的植物P胁迫下比较豆科植物时，菌根协会对P摄取的贡献是一致的，并且在P胁迫指数低于〜0.5时最为明显。豆科植物的内在根系形态决定了它们在磷获取效率上的差异，而与菌根定殖无关。菌根植物的产量响应与干物质分配到表土根部的减少有关，这意味着与菌根定殖相关的磷获取益处在缺磷的土壤中无累加。当在相同水平的植物P胁迫下比较豆科植物时，菌根协会对P摄取的贡献是一致的，并且在P胁迫指数低于〜0.5时最为明显。豆科植物的内在根系形态决定了它们在磷获取效率上的差异，而与菌根定殖无关。菌根植物的产量响应与干物质分配到表土根部的减少有关，这意味着与菌根定殖相关的磷获取益处在缺磷的土壤中无累加。当在相同水平的植物P胁迫下比较豆科植物时，菌根协会对P摄取的贡献是一致的，并且在P胁迫指数低于〜0.5时最为明显。豆科植物的内在根系形态决定了它们在磷获取效率上的差异，而与菌根定殖无关。当在相同水平的植物P胁迫下比较豆科植物时，菌根协会对P摄取的贡献是一致的，并且在P胁迫指数低于〜0.5时最为明显。豆科植物的内在根系形态决定了它们在磷获取效率上的差异，而与菌根定殖无关。当在相同水平的植物P胁迫下比较豆科植物时，菌根协会对P摄取的贡献是一致的，并且在P胁迫指数低于〜0.5时最为明显。豆科植物的内在根系形态决定了它们在磷获取效率上的差异，而与菌根定殖无关。