First selection of non-suckering rootstocks for hazelnut cultivars

One of the problems of hazelnut growing is the suckering habit, which varies according to cultivar. Sucker removal is a major cost and, when done, using herbicides causes environmental pollution. Furthermore, rootstocks are more pest and disease resistant, drought-tolerant, and kernel quality is improved. The use of non-suckering rootstocks (Corylus colurna L.) has proved to be a solution in the Balkan countries, although it is currently based on seedlings. Some Italian nurseries have recently begun producing clonal rootstocks by in vitro propagation, starting from genotypes not selected for specific traits. A trial to select non-suckering rootstocks was carried out by comparing trees of the main Italian cultivars (‘Tonda Gentile’, ‘Tonda di Giffoni’, ‘Tonda Romana’ and the newest released ‘Tonda Francescana’®) grafted onto a population of C. colurna L. to self-rooted ones (Corylus avellana L.). After four years of study, a first selection of the rootstocks was performed, based on tree vigor, early bearing, and yield efficiency, which was higher or similar to the best control (self-rooted) trees of the same cultivar. The rootstock ‘TGF2P4’ performed the best for vigor and yield efficiency for ‘Tonda Giffoni’; ‘TRF7P5’, followed by ‘TRF5P1’ and ‘TRF6P3’ performed the best for higher yield and vigor for ‘Tonda Romana’; ‘TGLF2P17’ and ‘TGL2P20’ performed the best for higher yield for ‘Tonda Gentile’; ‘TFF7P16’ and ‘TFF718’ performed the best for vigor and yield for ‘Tonda Francescana’® similar to the control trees. These rootstocks will be in vitro propagated to obtain clonal rootstocks with improved agronomic traits.