Yield, quality and genetic diversity of hybrid hazelnut selections in the Upper Midwest of the USA

The majority of hazelnut plantings in the Upper Midwest of the United States are planted with seedlings from crosses between American hazelnuts (Corylus americana) and European hazelnuts (C. avellana) that were initially made in the 1930’s. To evaluate the potential of this material to support a commercial industry, we have populated replicated field trials at five locations with clonal material of high performing accessions selected from these plantings. The hybrid plants in these trials were found to have high levels of genetic diversity when assessed at 10 microsatellite loci. Principal component analysis shows these Midwestern hybrids group genetically with American hazelnuts from the Upper Midwest region, but separately from European hazelnuts and hybrid hazelnuts developed elsewhere. We conclude that this pool of hybrids has sufficient genetic diversity for a breeding program to support a regional hazelnut industry. The average yield of the eight highest yielding of these genotypes, at ages six to 8 years, was 180 g m⁻² of canopy area at the most productive site, which in a production system with 50% of the land covered by the crop canopy would translate to 895 kg of kernel ha⁻¹. This compares favorably with expected yields of similarly aged European tree hazelnuts in Oregon. Though smaller than nuts from European cultivars, kernel quality of the top eight selections was deemed to be adequate for the processed nut market.