Influence of canopy density on fruit growth and flower formation

A study was carried out to assess if some degree of pruning might improve productivity of hazelnut trees in 'Tonda di Giffoni' and 'Tonda Romana' cultivars in central Italy. The pruning of increasing quantities of woods and shoots reduced leaf area index (LAI) and leaf area per tree. As for reducing canopy density, the LAI ranged from 9.5 to 5.4 in 'Tonda di Giffoni' and from 7.8 to 4.8 in 'Tonda Romana'; the incident photosynthetic photon flux density absorbed by leaves and recorded at the base of the canopy ranged from 92% to 87% in 'Tonda di Giffoni' and from 91% to 89% in 'Tonda Romana'. Canopy reduction effected yield per tree slightly in 'Tonda di Giffoni' and more in 'Tonda Romana'. Nut size increased in the trees where the canopy was less dense. Female and male inflorescence densities were highest in the trees with the largest leaf area in both cultivars. The sucker number increased in the most heavily pruned trees of 'Tonda Romana'. Hazelnut trees benefit from a canopy with LAI ranges around 7 probably because this density forms a high leaf area per tree with an incident photosynthetic photon flux absorption of about 90-91%, which can improve productivity and flower formation.