New disease-resistant hazelnut varieties allow for European hazelnut (Corylus avellana) production in the northeastern US where eastern filbert blight (EFB) previously hindered commercial growing. While these EFB-resistant hazelnuts are adapted to a wide area, their male flowers (catkins) can be damaged by frosts in colder regions, limiting pollen-shed and reducing yields. Fortunately, reports suggest wild American hazelnut (Corylus americana) may be cross-compatible with European hazelnut and is much less susceptible to catkin frost damage. In this study, a systematic approach will be used to determine the feasibility of American hazelnuts as pollenizers in European hazelnut orchards. Previous work at Rutgers identified multiple selections of frost tolerant, catkin-dense wild hazelnuts with pollen-shed spanning most of the bloom season, increasing the likelihood of pollination. These plants were sourced from diverse geographical backgrounds spanning the native range of C. americana. Pollen collected from these American hazelnuts (n=15) will be evaluated for viability and used in controlled crosses on Rutgers breeding selections slated for release in 2019. Pollen tube length and germination percentage will be determined using an in vitro agar-plate method. Incompatibility testing will be performed using fluorescent microscopy with collaborators at Oregon State University. Crosses will be harvested in September, with fruit set, physical qualities, and defect percentages analyzed for each pollen source and with respect to the female parent. This study will determine the use of the wild parents as pollenizers and select clones or seed sources for release to the emerging industry.
Project objectives from proposal:
1. Examine the in vitro germination percentage of cold hardy wild American hazelnut pollen, as well as determine incompatibility alleles (s-alleles) for the 15 wild American hazelnuts used in this study.
2. Determine germination percentage (percent fruit set) of American hazelnut pollen with European hazelnut female flowers from controlled crosses, and evaluate the resulting nut and kernel qualities and characteristics from successful crosses.