Alnus acuminata in dual symbiosis with Frankia and two different ectomycorrhizal fungi (Alpova austroalnicola and Alpova diplophloeus) growing in soilless growth medium

In this stud), we investigated the capacity of Andean alder (Alnus acuminata Kunth), inoculated with Frankia and two ectomycorrhizal fungi (Alpova austroalnicola Dominguez and Alpova diplophloeus ([Zeller and Dodge] Trappe and Smith), for nodulation and growth in pots of a soilless medium that contained vermiculite or a mixture of ground basalt rock and vermiculite. The seedlings were inoculated with Frankia suspensions prepared from root nodules of A. acuminata, followed by inoculation with spores of either one of the two Alpova species. The seedlings were grown in a greenhouse for 12 months. The seedlings grown in the vermiculite-based growth medium containing large (1-3 mm) basalt particles and Alpova austroalnicola or medium-sized (0.5-1 mm) basalt particles and A. diplophloeus had the heaviest shoot and root nodule dry weights and abundant ectomycorrhizal colonization. Ectomycorrhizas formed by A. acuminata with Alpova austroalnicola is described here for the first time. Growth of Alnus acuminata inoculated with ectomycorrhizal fungi and Frankia in the soilless primary minerals indicates that Andean alder can alter resource supply by tapping an otherwise unavailable nutrient source.