The production of flowers, fruit and leafy shoots in pruned macadamia trees

Abstract

For 'Macadamia integrifolia' Maiden and Betche var. 849, we compared four limb removal strategies of varying style and severity over 4 years, in terms of effects on yield, on the distribution of light, and new vegetative shoots, racemes and fruit within the canopy. Limb removal reduced yields. The reduction corresponded with the severity of pruning, not with the style of pruning. Limb removal had little impact in the medium term on light penetration to the orchard floor. Within the canopy, shoot production and raceme production were inversely related. Shoot production was favoured by high light conditions; raceme production occurred predominantly in areas of heavy shade, with 49% of racemes produced at canopy locations receiving less than 2% full daylight, and 94% produced at locations receiving less than 16% full daylight. Most flowering appeared to occur on wood more than 3 years old. The capacity of different parts of the canopy to support fruit set and retention increased with proximity to the more irradiated parts of the canopy, but fruit production was still high deep within the lower part of the canopy, with 50% of fruit produced at canopy locations receiving less than 2% full daylight, and 90% produced at locations receiving less than 16% full daylight.