Effect of Spacing and Sucker Removal on Precocity of Hazelnut Seedlings

Abstract

The effect of parentage, spacing, and sucker removal on precocity of hazelnut (Corylus avellana L.) seedlings was investigated. Wider spacing (1.2 vs. 0.6 m) within the row doubled the number of nuts per seedling in the 5th year but had no effect on nut count in the 3rd or 4th year, nor did it affect the percentage of seedlings bearing nuts in any of the three years. Differences among the four progenies were highly significant for number of clusters, number of nuts, and percentage of seedlings bearing nuts in all years and for number of years to first fruiting. The progeny `Barcelona' × OSU 55.097 had the most bearing seedlings in, the 3rd year but was outperformed by `Casina' × OSU 55.129 in the 4th and 5th years. Number of years to first fruiting varied from 4.3 for `Casina' × OSU 55.129 to 5.2 for `Tombul' × `Tonda di Giffoni'. Sucker removal increased both the percentage of seedlings bearing nuts and the number of nuts per seedlings, but the difference was not significant until the 5th year. Sucker removal reduced the length of the juvenile phase by 3 months. The use of precocious parents was more effective than sucker removal in shortening the juvenile period, while sucker removal and wide spacing within seedling rows increased the number of nuts produced by seedlings in the 5th year. Selection of seedlings for early initiation of bearing will shorten the breeding cycle, and the resulting new cultivars will be precocious when planted in commercial orchards.