Evaluation of Tonda Gentile delle Langhe clones

‘Tonda Gentile delle Langhe’ is one of the most interesting Italian hazelnut cultivars. Its superior nut quality is widely recognized and appreciated by the food industry. The typical growing area is in northwest Italy, in a hilly area called ‘Langhe’ where the cultivar has been propagated mainly by farmers using suckers. Only recently has the need for selected and certified plant material become evident. Research to identify clones with high kernel percentage and high productivity was previously conducted and 23 clones of ‘Tonda Gentile delle Langhe’ were selected from different orchards in the growing. These clones were described and planted in 1991 in an orchard collection in Cravanzana (Cuneo) for further evaluation. The clones were observed for four years for the following traits: nut weight, kernel weight, number of blanks, percent kernel, diameter and uniformity of the kernels, and ease of pellicle removal. They were also evaluated for cumulative yield. No significant differences among clones were detected for most of the examined characteristics. However, four clones appeared particularly interesting in comparison with the standard of ‘Tonda Gentile delle Langhe’ for yield and percent kernel, one of the most important characters for processing. In addition, RAPD analyses using 22 decamer primers were performed on the 23 clones in order to compare the genetic profiles of the plants and detect any intra-varietal variability. The DNA analysis produced identical profiles for the 23 clones, thus indicating the trueness-to-type of the selected plant material and the substantial genetic uniformity within the observed clones of ‘Tonda Gentile delle Langhe’.