|ISHS Acta Horticulturae 800: X International Pear Symposium
PERFORMANCE OF PEAR AND QUINCE ROOTSTOCKS WITH THREE CULTIVARS IN FOUR HIGH DENSITY TRAINING SYSTEMS IN THE NORTHEASTERN UNITED STATES
|Author: ||T.L. Robinson|
|Keywords: ||Pyrus communis, Cydonia oblonga, planting density, yield, fruit size, crop load, tree size|
A field trial at Geneva, New York State, United States compared four training systems/densities [Central Leader (598 trees/ha), Vertical Axis (1281 trees/ha), Tall Spindle (2243 trees/ha) and Super Spindle (5382 trees/ha)] on 6 rootstocks (seedling, OHF97, OHF87, Pyrodwarf, Pyro 2-33 and Quince A) with 3 varieties (Bartlett, Bosc and Taylor’s Gold Comice). After four years, tree density had a significant negative effect on tree size as measured by trunk cross-sectional area for each rootstock with trees at the highest planting density being only 55% the size of the trees at the lowest planting density.
With Bartlett, the largest trees were on OHF97 followed by OHF87, Pyro 2-33, Pyrodwarf and the smallest trees were on Quince A. However, with Bosc and Taylor's Gold the largest trees were on OHF87 followed by OHF97, Pyro 2-33 and Pyrodwarf.
Trees of Taylor's Gold on OHF97 and on seedling were damaged in the winter of 2004/05 with 37% of the scions killed.
The damage was greatest in the central leader system which had the most vigorous trees.
None of the other rootstocks were damaged.
Tree density had a large positive effect on yield in the third and fourth years with ‘Bartlett’ on OHF87 or Bosc on Pyrodwarf achieving 60 t/ha in the fourth year.
In contrast, the lowest density system (central leader) had only 10% of the yield of the highest density system.
There was a significant interaction of rootstock and variety with OHF87 being the best rootstock for ‘Bartlett’ but Pyrodwarf performing best with Bosc and Taylor’s Gold Fruit size was negatively related to planting density with the super spindle system producing significantly smaller fruit size than either the vertical axis or the central leader.
Part of the effect was due to greater crop loads on the super spindle system.
However, when fruit size was adjusted for crop load there was still a negative effect of planting density on fruit size of ‘Bartlett’. With ‘Bartlett’, Quince A produced the largest fruit size while Pyrodwarf and seedling had significantly smaller size.
OHF97, OHF87 and Pyro 2-33 had intermediate fruit size.
With Bosc and Taylor's Gold, there was no difference in fruit size between the rootstocks.
The greatest yield efficiency with ‘Bartlett’ was with Quince, OHF87 and Pyro 2-33. OHF97 and Pyrodwarf were intermediate while seedling had the lowest yield efficiency.
However with Bosc, Pyrodwarf had the greatest yield efficiency followed by OHF87, and Pyro 2-33, while both OHF97 and seedling had significantly lower yield efficiency.
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