Development of arbuscular mycorrhizal (AM) fungi and their influences on the absorption of N and P of maize at different soil phosphorus application levels

ObjectivesExploring the infection and reproduction of AM fungi and the effects of different AM fungi on the growth, the absorption of N and P of maize at different phosphorus (P) levels will help toscreen efficient and resistant to high phosphorus AM fungi.

MethodsA pot experiment was conducted using maize as test materials. A completely randomized block design with a two factors of AM fungi strains × phosphoruslevels of treatments was established. There were six AM fungi strains and four phosphorus applied levels (0, 50, 200, 500 mg/kg) in total, using no-mycorrhizae addition as controls. The growth and nutrient uptake of maize, and the infection rate, spore number, mycelium density of AM fungi were investigated.

ResultsAt P50 level, the infection rate, the arbuscular structure in root, the spore number, mycelia density of AM fungi were significantly higher than that of the treatment without P and P200 and P500 levels of P, and infection ability and growth of AM fungi was significantly decreased at high P level. AM fungal Funneliformis mosseae had the higher infection rate reached 75% and the higher mycelium density being 240 m/g than that of the other five AM fungi. The mycorrhizal infection of AM fungi C.c, R.a and G.et was the second, followed by D.s and C.eb. At P200 and P500 levels of P, F. mosseae had only the highest infection and fungi biomass. Inoculation with F.m, R.a and D.eb significantly reduced the N concentration of maize at the P0 and P50 levels. At P0 level, the inoculation with AM fungi significantly promoted the P concentration of maize plants, that of F. mosseae only at P50 level. At P0, P50 and P200 levels, the inoculation with AM fungi decreased the N/P ratio of maize. The N/P ratio of fungi inoculated with F. mosseae was significantly lower than that of other treatments.

ConclusionsRelatively low P concentration of 50 mg/kg in soilis more suitable for infection and growth of AM fungi. F.m, a strain resisted the higher P level in soil, shows the highest infection ability, following are C.c, R.a, C.et in turn. The inoculation of AM fungi is able to adjust the N and P balance in the plant roots, improve the plant nutrition status and promote the growth of maize.