Hybrids bred for nut production, intermediate in features between their parents.
USDA Hardiness Zone 4
RHS Hardiness Rating H7
Corylus heterophylla is the east Asian counterpart of the European C. avellana, and has long been utilised in China for nut production. The nuts are smaller and thick-shelled, but the plant is hardier. Cultivars of C. avellana (and/or C. maxima) have been cultivated in China since the start of the nineteenth century (Xie et al. 2005), but it was not until 1980 that attempts began at the Economic Forest Research Institute in Liaoning Provice to hybridise selected strains of native C. heterophylla with European fruiting hazels from Bulgaria, Albania and Italy (none of which were reliably hardy this far north in China). Compatibility was best when C. heterophylla was the seed parent. The five most promising strains were released in 1999 as ‘Pingdinghuan’, ‘Bokehong’, ‘Dawei’, ‘Jinling’ and ‘Yuzui’ (Molnar 2011). The general name for these hybrids in China is ‘ping-ou’, a portmanteau of ‘pingzhen’ (C. heterophylla) and ‘ouzhen’ (European hazels) (Wang et al. 2018). Four more hybrids, ‘Liaozhen 1’ to ‘Liaozhen 4’, were released in 2007–8, and 1200 ha of plantations were established in 2010 (Molnar 2011). The success of these orchards has led to a rapid expansion of commercial hazelnut production in northern China, centred on Liaoning and extending to 50,000 ha by 2016 (Wang et al. 2018).
A comparable breeding programme was begun by South Korea’s Rural Development Administration in 1975, but is less well documented. The selections ‘Poongsii’ and ‘Gaeam 1’ were released in the 1980s as hybrids of C. heterophylla (the selection ‘Ogyoo’ in the second case) with the old European clone ‘Butler’ (Molnar 2011).
Little genuine material of C. heterophylla has been available to western hazelnut growers interested in making similar hybrids. Open-pollinated seedlings from a plant in Quebec which was understood to be a hybrid of C. heterophylla have been selected by Ernie Grimo in Ontario and are sold as ‘Aldaro’ and ‘Andrew’. ‘Northern Blais’, originating at the Grimo Nut Nursery, has been selected in Quebec by Jacques Blais (Muehlbauer, Capik & Molnar 2021).