|Authors: ||E.A. Mielke, D. Sugar|
|Keywords: ||Pyrus communis, 'Old Home x Farmingdale', rootstock breeding, canopy volume, cumulative yield, fruit weight, yield efficiency|
The Horner series of pear rootstocks (545 seedling rootstocks) was created through open pollination of five Old Home by Farmingdale clonal rootstocks in an isolated area in western Oregon.
The size of ‘d’Anjou’ trees on a range of these rootstocks, as measured by trunk cross sectional area (TCSA), ranged from 33.5 to 76.9 cm2, with all but two of the Horner rootstocks exhibiting TCSA smaller than the control (OHxF 97 rootstock). Tree height, spread, and canopy volume (CV) were significantly affected by rootstock.
Trees with H-14 rootstocks were the shortest, and trees with H-4 rootstocks were the tallest.
The canopy spread of all trees with Horner rootstocks was narrower than the controls.
Trees with H-14 rootstocks were the narrowest.
The CV of all trees with Horner rootstocks was smaller than the control.
Trees with two Horner rootstocks (H-4 and H-10) produced more cumulative fruit and cumulative yields than the controls, and out-yielded the control by 23.6 and 8.8 tons per ha, respectively.
If tree density were adjusted for tree size through to the eighth leaf, trees with H-4 and H-10 rootstocks out-yielded the control by 27.7 and 32.4 tons per ha, respectively.
Trees with H-1, H-4 and H-10 rootstocks produced fruit that was larger than the control.
Trees with H-53 and H-14 produced the smallest sized fruit.
The yield efficiency (YE) of trees with H-10 rootstocks was almost 50% greater than the YE in the controls.
The YE of trees with H-4 rootstocks was greater than that of the controls even though the TCSA of trees with H-4 rootstocks was approximately 20% larger than that of the control.
Crop density (CD) was significantly affected by rootstock.
Eight of the thirteen Horner rootstocks had CD greater than the control.
Trees with H-4 rootstocks exhibited the greatest crop density.
Different patterns were observed between YE and CD.
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