In Spain, hazelnut is mainly cultivated in Catalonia, a region in the northeast. The province of Tarragona accounts for 88% of the total Spanish area planted to hazelnut. Almost 80% of the production in Tarragona is of the local cultivar Negret, with others cultivated to a lesser extent. Minor cultivars are only sporadically present in older orchards, farm yards and gardens, and have been collected for preservation. In this work, 16 SSR markers were used to fingerprint 18 minor hazelnut cultivars from northeastern Spain. Their microsatellite profiles were combined with those of 15 Spanish cultivars characterized in a previous work, and used to study the genetic diversity in 33 genotypes including local Spanish germplasm. The SSR analysis allowed development of unique profiles of each of the 18 cultivars, and no new case of synonymy was detected. A high level of genetic diversity (mean H e = 0.7) was observed in 33 genotypes, although a high number of them showed a close genetic relationship. The dendrogram generated by UPGMA cluster analysis placed the 33 accessions into nine main groups, related to their putative pedigrees or geographical area of cultivation. All investigated Negret-type cultivars were found to be distinct from Negret, and only a few cultivars within this germplasm appeared to be seedlings of Negret. The results will be useful in the conservation of hazelnut germplasm and in the selection of parents for use in breeding.
Paolo Boccacci, Roberto Botta and Mercè Rovira
Mercè Rovira, Juan Francisco Hermoso and Agustí J. Romero
Eleven hazelnut (Corylus avellana) cultivars, four Spanish (Clon La Masó, Negret N-9, Negret Primerenc, and Pauetet), four Italian (San Giovanni, Tonda Italiana, Tonda di Giffoni, and Tonda Romana), and three cultivars from Oregon State University’s (OSU) breeding program (Clark, Lewis, and Willamette), were evaluated in northeastern Spain over a period of 15 years (2001–14). The trial was planted at the Institute of Agriculture and Food Research and Technology (IRTA)-Mas de Bover Station (Constantí, Spain) in 2001, using own-rooted material, in single-trunk, 6 × 3.5-m spacing, and fitted with drip irrigation. Tree vigor, sucker production, early bearing, and total crop were recorded during the first 9 years. Nut traits were studied over 7 years and nutritional composition analyzed in 3 years. The best agronomic performance was observed in ‘San Giovanni’, ‘Pauetet’, ‘Clon La Masó’, and ‘Tonda Italiana’ that scored the highest total crop and canopy volume, but ‘San Giovanni’ and ‘Clon La Masó’ produced a high number of suckers. The best industrial value of the kernel was given by ‘Tonda di Giffoni’, ‘Negret N-9’, ‘Willamette’, and ‘Clark’ with high roasting aptitude and high fat content, although ‘Negret N-9’ was a little poor in monounsaturated fatty acids. The three cultivars from the Oregon breeding program had good agronomic behavior and industrial potential, but were not an improvement on the traditional Mediterranean cultivars.