Role of mycorrhizal inoculation in enhancing phosphorus nutrition of soybean in p-deficient soils

Abstract:

Arbuscular mycorrhizal fungi act as an underground extension cord for plant roots-plugging into phosphorus pools that roots alone can’t reach. This research evaluated the effect of inoculation with Glomus intraradices, Acaulospora laevis, and a mixed consortium on phosphorus uptake, growth, and grain yield of soybean (cv. Snowy) in a P-deficient red Chromosol (Colwell P 8.4 mg kg⁻¹) at the Murray-Darling Institute of Agriculture, Wagga Wagga, NSW, Australia, during 2022-23 and 2023-24. A randomized complete block design with four treatments and four replications was used. Mixed AMF inoculation produced the highest root colonization (71.3%), cumulative P uptake (64.8 mg plant⁻¹), shoot biomass (21.4 g plant⁻¹), nodule count (36.8 per plant), and grain yield (24.7 g plant⁻¹)-representing increases of 87.3%, 68.4%, 72.6%, and 69.2% over the uninoculated control. G. intraradices alone was the best single-species inoculant across all parameters. P uptake accelerated most between 45 and 75 days after sowing, coinciding with peak root colonization. These results confirm that AMF inoculation can partially substitute for P fertilizer in low-P Australian soils, with mixed consortia performing best.