THE EFFECTS OF SEASONAL VARIATION ON NUT FALL IN AUSTRALIA

Hazelnuts were picked up from the ground on a weekly basis at two field sites in the summers of 2000, 2001 and 2002. The field sites were at Orange in New South Wales and at Myrtleford in Victoria. Nut numbers and weights were recorded at each pick up time. At the Myrtleford site, the samples collected were also cracked to assess how kernel quality was influenced by time of nut fall. Periods of peak fall were noted for each genotype. The number of heat units accumulated to peak nut fall was determined from temperature data obtained from the automatic weather stations at each site. Daily heat units were calculated from mean daily temperature, subtracting 10°C. Regression analyses were carried out on the time of peak nut fall and accumulated daily heat units from 1 and 15 December each year. It was found that heat units had a significant (P=0.05) influence on the time of peak nut fall. On average, 927 accumulated heat units were recorded until nut fall for the cultivar ‘Barcelona’ over 102 days from the beginning of December.