Influence of irrigation on nut traits, production and photosynthetic activity of hazelnut cultivar Tonda di Giffoni

The present trial, supported by the project FRU.MED. MIPAAF, has been carried out in 2006 in a experimental farm located in Caserta province, Southern Italy. Five year old plants of the local cv. Tonda di Giffoni were spaced 5 x 5m and trained to free vase. Starting from 2006, four treatments were applied: an unirrigated control and three different water levels, corresponding to the restitution of 50, 75, 100 % ETM by means of a drip irrigation system. The plant yield increased at the highest irrigation volumes. Nut fall at ripening was more concentrated in the unirrigated control in comparison whit the irrigated plants. Nut and kernel weight and size were greater in irrigated than in control plants, with the highest values observed in 100 % ETM treatment. The percentage of empty and defected nuts was higher in condition of limited water availability. The oil content in the kernel of unirrigated control and at 50 % ETM restitution was slightly higher than in the other treatments. Leaf assimilation rates during the summer 2006 showed low differences among treatments, with more uniform values during the day at 100 % ETM. In conclusion, considering all observations effected, water supply of 75 % and 100 % ETM could be valid irrigation levels to obtain high yield, good technological traits of the nuts and reducing the cost of irrigation.