DETERMINATION OF OLIVE LEAF BORON CRITICAL LEVELS IN NORTHERN ITALY

Morainic soils of Lombardy are low in boron and olive tree standard
nutrition practices are frequently inadequate for optimal yield.
The aim of this work
was to develop leaf threshold values for boron nutrition and to study the effect of
boron and pollen treatments on fruit set.
The work was split in two different
experiments: olive trees with either low and good fruit set.
In the first case the trees
were able to bloom but not to set fruits, while in the second case there was a good
relationship between bloom and fruit set.
Two cultivars, ‘Leccino’ and ‘Casaliva’,
were assessed over three years in two olive orchards.
In the first experiment boron
treatments were applied either before and soon after flowering, while in the second
one the effect of different boron spray concentrations and the additive effects of
pollen application were tested.
Critical leaf boron concentration was cultivar
dependent: at the same boron contents ‘Casaliva’ set better than ‘Leccino’. Levels of
15-20 mg/kg of boron on dry weight seemed to be the critical threshold for fruit set
while 20-40 mg/kg seemed to be optimal.
When the leaf boron concentration
increased the fruit set decreased.
Pollen treatments resulted ineffective.

V International Symposium on Olive Growing

O. Failla, S. Pedò, D. Bassi, C. Gigliotti

foliar fertilization, fruit set, Olea europaea L.

https://doi.org/10.17660/ActaHortic.2008.791.116