ISHS Acta Horticulturae 65: Symposium on High Density Planting
INITIAL AND MAXIMUM YIELDS IN SELECTED PLANTINGS AND THEIR RELATIONSHIP TO MAXIMUM DENSITY |
| Author: | A.D. Crowe |
| Abstract:
The capital cost of high tree density plantings of apples can only be justified if the whole orchard produces earlier and consistently gives higher yields than less dense plantings. Yields over periods of up to 40 years in 12 orchards containing over 20 scion clones and 24 stock clones at spacings of 48 to 2900 trees per acre (119 to 7165 trees/ha) showed initiation of yield was spasmodic rather than a steady progression. Based on studies of shade effects and light regimes, theoretical projection of tree canopy functional volume suggests leaf efficiencies must be greater by a factor of 2 to 3 in orchards spaced at 1.50 m compared with those at a 3 m spacing. While insufficient for proof, the 12-orchard data suggest such efficiencies may not be achievable. We therefore recommend planting at 14' x 20', 155 trees/acre (4.3 m x 6.1 m, 383 trees/ha). We are concentrating our research on methods to achieve consistent high early yield without tree losses and on identifying maximum mature yields. | |
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