ISHS Acta Horticulturae 732: VIII International Symposium on Canopy, Rootstocks and Environmental Physiology in Orchard Systems
EFFECTS OF TREE DENSITY AND TREE SHAPE ON APPLE ORCHARD PERFORMANCE |
| Author: | T.L. Robinson |
| Keywords: | Malus × domestica, planting system, rootstock, pruning, training, light interception, light conversion efficiency, partitioning index |
| Abstract:
A replicated field trial compared 8 tree densities (range 598-5382 trees/ha) and two tree shapes (conic and V) with 4 apple cultivars ('Gala', 'McIntosh', 'Empire' and 'Fuji'). At the lowest 2 densities, trees were planted on 'M.7' rootstocks (598 trees/ha) and 'M.26' rootstocks (840 trees/ha). At all the higher densities, trees were planted on 'M.9'. After 7 years, there was a strong negative effect of tree planting density on trunk cross-sectional area. Among M.9 treatments, the highest planting density produced trees about 1/3 the size of the lowest planting density. The highest density system achieved a yield of 50 t/ha in the fourth year while the lowest density system never surpassed 25 t/ha. Tree density had a highly significant negative effect on cumulative yield per tree, but had a highly significant positive effect on yield per hectare. The cumulative yield of the highest tree density was 3 times greater than the lowest density. There was a significant interaction of tree shape and tree density on cumulative yield. At the higher tree densities, the V-shape had lower cumulative yield than the conic shape while at lower tree densities the V-shape was superior to the conic shape. Tree density had a strong effect on canopy light interception from year 2 through 7. The highest tree density achieved 60% canopy light interception by year 6. There was no effect of tree shape on light interception until year 4 after which the V-shape surpassed the conic shape at similar densities. Cumulative yield was a function of light intercepted. However, there was a significant interaction with tree shape. The V-shape intercepted more light, but at high tree densities, it had lower yield than the conic shaped trees. Increasing tree density had a negative effect on partitioning index of 'M.9'. At the highest tree density the partitioning index of 'M.9' was reduced to a similar level as 'M.7'. | |
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