Economic and biological factors determining productivity in a young hedgerow planting of apples

Abstract

Data for the first eight years of a planting of Jonathan, Delicious and Granny Smith apples on MM.102, MM.104, MM.106 and Northern Spy (NS) rootstocks are considered. Spacings of 3.7 m (440 trees ha-') to 1.9 m (862) in steps of 0.15 m were used in rows 6.1 m apart. Trees were pruned to a central leader. Jonathan, Delicious and Granny Smith on NS and MM.106 rootstocks produced bigger trees at the wider spacings, as did Granny Smith on MM.104 and Delicious on MM.102; the size of Granny Smith and Jonathan trees on MM.102, and of Delicious on MM.104, was not affected by spacing ; Jonathan on MM.104 produced the biggest trees at the closer spacings. Yield per tree was not affected by spacing. Granny Smith gave highest yield over the period, followed by Delicious; for rootstocks the order was NS, MM.106, MM.104 with MM.102 last. Commercial quantities of fruit were produced after four years and a total of around 80 t ha-' was produced between ages four years and eight years from trees planted 3.7 m apart. Trees planted 1.9 m apart produced around 130 t ha-l over the same period. The quality of fruit from the trial was comparable with commercial fruit, and there were no apparent differences in quality between fruit from densely spaced and from widely spaced trees. After taking into account costs of production such as sprays, fertilizer and labour, and estimated market price, the approximate cumulative net returns per hectare over the five years were : $7420, $11,540 and $12,390 ¦ $440 for Jonathan, Delicious and Granny Smith cultivars. For rootstock net returns were $781 0, $831 0, $1 2,500 and $1 3,200 ¦ $500 for MM.102, MM.104, MM.106 and NS. Net returns increased by $326 ¦ $68 for each 0.1 5 m unit decrease in spacing. These results indicate that apples planted at higher densities than normal and pruned to a central leader are far superior to the current Australian apple plantings in yield per hectare and in productivity.