Maximizing the symbiosis of tuber iyonii with carya illinoinensis
Hamilton, William Marshall
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Truffles are the culinary desirable ascocarps of the fungal genus Tuber. Tuber lyonii (pecan truffle) is a species of truffle endemic to North America and can also be found in pecan (Carya illinoinensis) orchards. Its proclivity to form ectomycorrhizae with pecan trees is the driving factor behind the research described here. The overall objective was to maximize colonization of pecan seedling roots by T. lyonii. Two varieties of pecan rootstock, ‘Elliott’ and ‘87Mx5-1.7’ were tested and both formed ectomycorrhizae with T. lyonii when grown in containers and exposed to greenhouse culture conditions. Inoculation with T. lyonii led to taller seedlings with larger stem diameter in both varieties of rootstock. Fertilization treatment influenced colonization percentages. The foliar inorganic application treatment had the highest mean T. lyonii colonization compared to a foliar organic and inorganic soil drench applications. Colonization percentages were higher in root samples collected from near the substrate surface as compared to samples from the lower portions of the root system. Vernalization and fungicide application did not influence T. lyonii colonization in pecan roots, which remained statistically similar in treated and untreated plants. Results show that pecan seedlings can be successfully grown in containers in symbiosis with T. lyonii with implications for nursery production and management of inoculated seedlings. While further optimization of the production system may be required, this work is a significant first step toward developing reliable methods for producing and managing pecan truffle inoculated pecan seedlings.