(371) Hydroponic Inoculation of Cranberry with Ericoid Mycorrhizal Fungus

Abstract

Cranberry (Vaccinium macrocarpon) plants colonized with ericoid mycorrhizal fungi are capable of utilizing organic nitrogen sources that are unavailable to non-mycorrhizal plants. Despite the importance of mycorrhizal colonization in the nitrogen nutrition of wild cranberry, almost all measurements of cranberry nitrogen uptake and assimilation have been carried out with non-mycorrhizal plants. We have found that cranberry can be inoculated directly in solution culture. We cultured the ericoid mycorrhizal fungus Hymenoscyphusericaein liquid culture, harvested and rinsed hyphae, and added ≈200 mg fresh weight hyphae per rooted cranberry cutting (cv. Stevens) growing in a modified Johnson's solution. After 6 weeks, newly developed roots were most heavily colonized. We examined the effects of NH4+ concentration (5, 10, 20, 50, 100, and 500 μm NH4+) in solution on colonization rates. Colonization (% root length) increased with increasing ammonium concentration in solution, with maximum colonization at 50 and 100 μm NH4+; colonization was much lower at 500 μm NH4+. Cranberry inoculated with H. ericaein solution culture will be used for analysis of the effects of mycorrhizal colonization on uptake kinetics of NH4+, NO3-, and amino acids.