Inoculation with ericoid mycorrhizal fungi alters fertilizer use of highbush blueberry cultivars

Abstract

Seven highbush blueberry cultivars were inoculated with one of three different isolates of ericoid mycorrhizal fungi (EMF) and grown in pots for 2 years with either inorganic or organic fertilizer. Root colonization of noninoculated plants was low (<15%) regardless of fertilizer source. Root colonization on inoculated plants was 15-30%. Colonization was typically higher when plants were grown with organic fertilizer. Inoculation generally increased plant growth but decreased root:shoot biomass ratios regardless of the type of fertilizer used. Inoculation also increased nutrient uptake and/or nutrient use efficiency in several cultivars, particularly when plants were fertilizer with organic fertilizer. Without inoculum, however, some cultivars fertilized with organic fertilizer had less growth and lower concentrations of N, K, S, and Cu than those fertilized with inorganic fertilizer. Cultivars that were genetically close in ancestry showed a high degree of variability in response to mycorrhizal fungi, while responses to fertilizer type were similar in closely related cultivars. Results suggest that nutrient availability may influence colonization and growth responses to EMF; however aspects of fungus-host specificity and inoculum availability also play a role in EMF colonization of roots in container production.