High-density orchards come into bearing early and have a greater yield per unit land area than conventional plantings. Individual trees have higher production efficiencies and reduced amounts of nonproductive wood. Cumulative yield per hectare is related to tree density during the initial life of the orchard. Thus, increasing planting density can, up to a point, increase total yield. However, besides cumulative yield, it is important to consider yield per tree and yield efficiency (yield per unit of trunk cross-sectional area) to more accurately compare different high-density systems. Although a slender spindle planting will have a greater cumulative yield during the initial years than a low trellis hedgerow with half as many trees per hectare, yield per tree and yield efficiency tend to be higher in the latter.
High-density systems have better fruit quality than low-density systems, and this is best expressed in terms of fresh fruit packout, which is a true measure of marketability and thus profitability. Improved tree canopy light interception results in a higher percentage of extra fancy and fancy grade fruit (Figure H2.1). The downgrading of fruit because of disease and insect damage is also reduced due to an improved environment within the tree and better spray coverage.
Central Trellis Slender
Leader Hedgerow Spindle
247 1,494 3,982
trees/ha trees/ha trees/ha
□ Extra Fancy/Fancy Packout
FIGURE H2.1. Tree density and training system effects on 'Golden Delicious' light transmission and packout (Source: Modified from Baugher et al., 1996.)
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