The effects of row orientation, tree height, time of year and latitude on light interception and distribution in model apple hedgerow canopies

Abstract

A computer model was used to calculate light interception and distribution within apple hedgerow canopies at different times of the year, at row spacings of 2, 3 and 4 m, at latitudes of 51.3, 40 and 30°N, for tree heights from 0.5–4 m, with row orientation N–S or E–W and at constant leaf area density. The effect of row orientation was complex and depended on the other factors. In mid-summer, N–S rows intercepted more light than E–W rows with larger differences at lower latitudes and at the wider spacings. At the equinox, E–W rows intercepted more light than N–S rows at higher latitudes Iput there was little difference at 30°N. Light interception was not affected by row orientation when hedge height was less than 1 m, or at 2 m row spacing on days with low solar altitudes. Light distribution was improved with wider spacings in N–S rows, but this was only the case for E–W rows when solar altitudes were low. Light distribution was better in N–S rows in mid-summer at the time of floral initiation but this was reversed at 51.3°N at the equinoxes.