Effects of density,rectangularity and row orientation on apple trees,measured in a multiv ariated experimental design

A single-plant-plot design was found very suitable for a study of growth and yield effect of tree density, rectangularity and row orientation on a wide range of intra and inter-row planting-distances.Densities from about 250 to 40 000 trees per hectare were studied in 2 apple cultivars on 2 weak-growing rootstocks over a period of 8 years. On unpruned trees a maximum yield of 80 tons per hectare of ‘James Grieve’ and about 95 tons of ‘Spartan’ was recorded. At the highest densities these yields were reached 2–3 years after planting.As early as the second to third year the growth was restricted at densities over about 1000 trees per hectare. A higher yield per tree at medium densities than at lower densities for the first fruiting-years is supposed to be an effect of growth resulting in earlier fruiting.A high rate of rectangularity reduced the yield only on densities of 1200–1550 trees per hectare. The lack of a significant effect on lower and higher densities is discussed.The growth and yield of rows oriented North—South were 17% higher than of those oriented East—West.