S16 - Session P2 - Architecture and yield relationship in hazelnut tree

Authors: Francesca Grisafi *, Daniela Farinelli, Evelyne Costes, Frédéric Boudon, Jean-Baptiste Durand, Sergio Tombesi

Alternate bearing affects many fruit tree species, including hazelnut ( Corylus avellana) . Studying plant architecture could provide useful information for improving crop management, such as pruning, to reduce the impact of alternate bearing. This work aimed to compare the relationship between bud composition and shoot length in hazelnut shoots. The experiment was carried out in January 2020 and 2021 in Deruta, Perugia (Italy). In 2020 104-year-old shoots of C. avellana (cv. Tonda di Giffoni) (parental) were studied. In 2021, the same studies were performed on lateral and apical 1-year-old shoots (children) that burst from parental buds in spring 2020. For each shoot, shoot length, axillary and apical bud type composition, at each node, was recorded in 2020 and 2021. According to the shoot length, each shoot was classified into four different categories: short (Sh) when less than 5 cm, medium (Me) when between 5 and 20cm, long (Lo) when between 20 and 40cm, and very long (VLo) when more than 40cm. Four types of observation were recorded at each node: vegetative buds, blind nodes, catkins, and mixed buds (V, B, C, and M, respectively). It was observed that the length of lateral children, developed in 2021, was related to the length of the parent. Children lateral Sh shoots were the most frequent among all parental length categories while longer children shoots (Lo and VLo) were originated only from parental VLo shoots. The percentage of lateral mixed buds is slightly higher in Sh shoots than in longer ones while vegetative buds' percentage remains constant along the different lengths. Yield efficiency, computed as the ratio between the number of nuts and the number of mixed buds, was significantly higher in Lo and VLo shoots. Indeed, in hazelnut, buds frequency is different according to shoot length. Managing architecture, considering a good balance between long and sho rt shoots, could help in decreasing alternate bearing in hazelnut trees.