Inoculation of green alder ([Alnus crispa]) with Frankia-Ectomycorrhizal Fungal Inoculant Under Commercial Nursery Production Conditions

Abstract

We examined the feasibility of producing container <i>Alnus crispa</i> (Ait.) Pursh (Betulaceae) seedlings (green alder) inoculated with a pure culture of <i>Frankia</i> sp., Brunchorst strain AvcI1 and an ectomycorrhizal fungus, <i>Hebeloma crustuliniforme</i> (Bull. ex st. Amans) Quél. in a commercial nursery setting. Alders are actinorhizal plants that fix atmospheric nitrogen in a symbiotic association with <i>Frankia</i> species and can also form mycorrhizal associations. <i>Frankia</i> inoculation significantly increased seedling biomass, number of nodule lobes, nodule weight, and plant nitrogen content of green alder at the end of nursery culture compared with control or “<i>Hebeloma</i> only” treatments. Improved seedling growth, root nodulation, and nitrogen nutrition achieved in this study was attributable to <i>Frankia</i> inoculation, suggesting <i>Frankia</i> inoculation in nursery may be beneficial for the production of superior alder seedlings to use in reclamation work. Actinorhizal plants have the potential to enhance plant establishment on disturbed sites and to improve soil fertility and stability. Seedlings inoculated with <i>Hebeloma</i> only or in combination with <i>Frankia</i> did not show any visible ectomycorrhizal colonization, suggesting <i>H. crustuliniforme</i> may not be compatible with green alder under these experimental conditions. This study demonstrated the suitability of producing large-scale inoculated alder seedlings in commercial nurseries without altering regular nursery operations.