Seasonal light interception and canopy development in hedgerow and bed system apple orchards.
Patterns of light interception, in both time and space, were measured during 1973 and 1974 in apple orchards. Several planting systems were investigated and the patterns of light interception were related to structural area (leaf area index, branch area index and fruit area index). Leaf area increased rapidly in May and June and then usually declined slowly until leaf-fall in October/November. The largest recorded light interception was just over 60% by a bed system of Cox's Orange Pippin during the beginning of September, 1973. All orchards showed a seasonal hysteresis when light interception was plotted against total structural area. This hysteresis was due to changes in canopy size and solar altitude. The bed systems of planting showed the largest seasonal changes in both canopy size and hysteresis. The results are discussed in relation to planting designs in orchards.