Long Term Evaluation of Hazelnut Response to Drip Irrigation

A long term evaluation of hazelnut plant response to irrigation is important in agronomic management, in areas where water availability is limited. Drought conditions are becoming common in the Mediterranean area, like in Latium and Campania, which are the most important regions for the hazelnut production in Italy. Hazelnut is a water stress-sensitive species, then the irrigation is an appropriate technique to improve plant growth and productivity, according to plant water balance. The trial examined the plant response in the cultivar 'Tonda Gentile Romana' subjected to three irrigation levels, over the period from 2001 to 2010, in an experimental orchard established in 1992, at the farm of the University of Tuscia. The volumes of irrigation corresponding to the restitution of 50, 75, 100% crop evapotranspiration (ETc), as calculated from class A evaporation pan, were applied by means of drip irrigation and compared with not-irrigated plants, used as control. Vegetative growth and yield characters were positively affected by irrigation. The highest yield was obtained at the 75% Etc level of irrigation for almost all years. Nut and kernel weight and size, and percent kernel were slightly greater in the irrigated treatments than in the control. The percentage of empty and defected nuts was higher under conditions of limited water availability. Taken all data, water supply of 75% ETc resulted to be a valid irrigation level for cultivar 'Tonda Gentile Romana', in areas characterized by insufficient rainfall during the year.