Can light interception of intensive apple and pear orchard systems be increased with new approaches to tree design?
2016
Tustin, D. S. | van Hooijdonk, B. M.
Internationally, most intensive planting systems of apple and pear are grown as 'tall spindle' central leader trees or inclined-vee variations of central leader trees. Many studies of the production physiology of these planting systems over several decades show the upper limits of light interception to be approx. 65% of incoming radiation, achieving yields just exceeding 100 t ha-1 from the highest yielding systems. These metrics also demonstrate that the theoretical productivity of apple orchards at 90% light interception could be 170-180 t ha-1. The challenge to intercept 85-90% light cannot be achieved without departing from the 'tall spindle' tree and row alleys for large vehicles, if the appropriate canopy light relations for fruit quality are to be retained. We present new concepts for tree architecture in planting systems arrays designed to meet the physiological requirements for high quality fruit, combined with potential for greatly increased light interception and thus, productivity. In true systems approaches, the potential to increase biological efficiency using redesigned nursery trees from the outset is examined. New tree architecture concepts and the rationale when scaled up to the orchard planting system are discussed. Factors considered include the potential for increasing harvest index together with increased light utilisation and the future economic necessities of labour and capital efficiency, mechanisation and automation. Orchard canopy light interception at the end of the first year of growth was compared between the new 'super-orchard' planting systems and a same-aged comparator 3.0×1.5 m 'tall spindle' planting system.
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