BORON DOES NOT INCREASE HAZELNUT FRUIT-SET AND PRODUCTION

In a 3-year experiment in two drip-irrigated orchards on the Mediterra nean coast, boron (B) sprays applied at rates of 0.6 and 1.2 g per tre e and a soil B application of 12 g per tree did not increase fruit set or production of Corylus avellana L. 'Negret' and 'Pauetet' hazelnuts with mid to low foliar B levels (14.3 to 21.8 mu g.g(-1) dry mass). T he average fruit set and nut yields of the trials were, respectively, 66% and 3.54 kg per tree for 'Pauetet', and 50% and 4.54 kg per tree f or 'Negret'. The lack of response to B applications might be due to 1) initial fruit set levels mere high; 2) the current B recommendation g uidelines (25 to 30 mu g.g(-1) dry mass) might be adequate for fruit s et and yield; 3) the rates of B applied might be too low; and 4) weath er and soil conditions, cultivars, and biennial bearing may have maske d any response to foliar B application.