HAZELNUT PRODUCTIVITY IN NORTHERN PORTUGAL: AN ECONOMETRIC APPROACH
Several commercial hazelnut cultivars located in northern Portugal were evaluated for growth and nut production from 1980 onwards. In a multistemmed trial containing eleven cultivars fruit production only became meaningful in the 6th year, when trees produced about 1.59 t/ha. Plant growth was very varied, the smallest bushes being Daviana and L. d'Espagne, which can be cultivated at 6 x 4 m under local conditions. The most vigorous cultivars were Segorbe and F. Coutard which require larger spacings at around 8 x 6 m. In this paper, we apply the Hodrick-Prescott filter to decompose the annual production of the eleven cultivars into their trend (long-run yield) and cyclical (fluctuations around the trend) components for the 1985-2001 period. The results suggest that the eleven cultivars could be classed into four groups: a first group that clusters the 6 most productive cultivars: Butler, F. de Coutard, Morell, Segorbe, Gunslebert and R. Piemont; a second that groups the medium-productive Grossal, L. dEspagn and M. Bollwiller; a third represented by the cultivar Ennis, evidencing a precocious decline in production, which may be a sign of lack of adaptation to local conditions; and a fourth, occupied by the pollinizer Daviana, which demonstrates a low rate of production and a marked cyclicity. The cyclical variation may have been due to variations in climatic conditions during pollination periods, which may also have caused different rates of blanks.
Santos, A., Correia, L. and Rebelo, J. (2005). HAZELNUT PRODUCTIVITY IN NORTHERN PORTUGAL: AN ECONOMETRIC APPROACH. Acta Hortic. 686, 547-556
Corylus avellana L., filbert, production, cultivars, detrending, time series