Last Results in the Evaluation of 'Negret' Hazelnut Cultivar Grafted on Non-Suckering Rootstocks in Spain

`Negret'is the most widely planted hazelnut cultivar in Tarragona (Spain). One of the disadvantages of this cultivar is the high suckers'emission, causing high maintenance costs yearly. In 2000, a trial to select new and non-suckers emission rootstocks for hazelnut was established at IRTA-Mas de Bover. 'Negret-N.9' selection was grafted onto four clonal rootstocks (' Dundee'and ' Newberg', two open pollinated C. colurna seeds; the low suckers emission cultivar 'Tonda Bianca'and 'IRTA-MB.69'selection) and compared to the own-rooted 'Negret-N.9'. The trial was statistically designed by randomized complete block with ten replications, and one tree per replication and clonal rootstock. Vigor, suckers emission, production and nut characteristics have been evaluated during nine years. The last five years of the trial, kernel quality properties were added to the characterization. Results showed that some rootstocks have a strong influence on vigor and yield of 'Negret N.9'during the period 2003-2011. 'Dundee'and 'Tonda Bianca'rootstocks showed the highest vegetative growth, whereas 'Dundee', 'Newberg'and 'MB-69'showed the lowest suckers emission. Yield performance was highest in 'Dundee'and contrary to 'Tonda Bianca'that showed the lowest yield. Referring to kernel quality studies, rootstocks have a positive influence on oil stability and induces a brown light color in the kernel pellicle, in contrast with the brown dark color in own-rooted 'Negret N.9'. Kernel fatty acid composition was also influenced by the kind of material used (own-rooted or grafted trees).