CORRELATIONS BETWEEN LEAF MINERAL CONTENT AND PRODUCTION AND QUALITY PARAMETERS, IN AN EXPERIMENTAL ORCHARD OF ´NEGRET´ HAZELNUT (CORYLUS AVELLANA L.)

A field experiment was set up in a mature cv. Negret hazelnut orchard in La Selva del Camp, Tarragona (northeast Spain), in order to study the effects of several different treatments on yield and nut quality. The experiment was conducted over six years (1998-2003). The field experiment was conducted applying the following quantities of general fertiliser: 50 kg N/ha, 70 kg P₂O₅/ha, and 110 kg K₂O/ha and irrigating according to local custom. This served as the reference treatment. Nitrogen treatments: 50, 100, 150 and 200 kg N/ha. Boron treatments: a foliar spray treatment of 2.5 l/tree with a solution of 500 mg B/l and another treatment applied to the soil at 50 g B/tree. A Boron foliar spray treatment was combined with an iron treatment applied to the soil at 30 g Fe/tree in chelate form (EDDHA): it contained 6.5% Fe. There were a further four irrigation treatments, two of which involved regulated deficit irrigation. Mineral leaf content correlated negatively with yield. After years of high yield, normal leaf levels were restored in the following year. The reference P leaf levels should be revised for ‘Negret’ hazelnut in Tarragona conditions and lower reference levels could be accepted. The nut quality parameters studied (kernel yield, kernel size and brown spots in kernel cavity) were not affected by low P leaf levels. The Mn leaf content (865 ppm) was very high in comparison with reference levels (250 ppm), however yield and nut quality were not affected.