Articles
WORLD-WIDE DEVELOPMENT OF HIGH DENSITY PLANTING IN RESEARCH AND PRACTICE
Theoretical analysis has shown the volume of well-illuminated canopy to increase with the proportion of ground surface shaded and the maximum volume of well illuminated canopy to be most efficiently achieved when the foliage is evenly distributed over the orchard surface by use of evenly spaced dwarf trees or horizontal or angled trellis systems.
With such trees an LAI of 2 can intercept more than two thirds of the available light with minimal within-tree shading.
Economic analysis shows the dominant importance of fruit quality, which is only achieved in well-illuminated zones of trees, and of planting costs if high density systems are used – in which case early heavy crops are essential to repay these costs.
Control of shoot growth above and external to the cropping zone is essential to maintain fruit light exposure and quality.
Results with specific systems over the last 20 years show an ever more widespread relative advantage of high-density, shallow canopy systems.
This is a result of improvements in tree management and pruning, especially to give precocious cropping and good fruit quality at maturity.
In particular slender spindle and axe systems are now proving advantageous with a much wider range of varieties and in more countries than hitherto.