ISHS Acta Horticulturae 658: I International Symposium on Rootstocks for Deciduous Fruit Tree Species
PEAR CULTIVARS USED AS INTERSTEMS SHOW PROMISE AFTER EIGHT YEARS IN TWO OREGON LOCATIONS |
| Authors: | E.A. Mielke, D. Sugar |
| Keywords: | Pyrus communis, 'Old Home x Farmingdale', interstem, canopy volume, cumulative yield, fruit weight, yield efficiency |
| Abstract:
Size controlling rootstocks are available for a number of tree fruits, but are not widely available for pear. Interstems have been shown to reduce tree size, increase productivity and fruit size, and delay the flowering period in a number of tree fruits. The objective of this trial was to determine if the use of pear cultivars as interstems would reduce tree size, and improve fruit size and production. Interstems significantly affected the trunk cross sectional area (TCSA) measured fifteen cm above the lower bud union. Trees grown in Hood River were approximately twice as large as those grown in Medford. In both locations trees with ‘Bosc’ interstems had the largest TCSA, and trees with ‘Bartlett’ interstems had the smallest TCSA. Interstem and cultivar significantly affected the TCSA measured five cm above the upper bud union. ‘Comice’ trees with ‘d’Anjou’ and ‘Bartlett’ interstems exhibited larger TCSA above the upper bud union indicating overgrowth was occurring. Interstem also affected tree height, spread, and thus canopy volume (CV). Trees with ‘Conference’ interstems generally were the shortest, had the narrowest spread, and the smallest CV. TCSA and CV did not follow the same pattern and gave different impressions of tree size. Cumulative fruit production in Hood River was approximately twice as large as in Medford, the differences between interstems were larger in Hood River, and generally followed the pattern observed in TCSA. Trees with ‘Bosc’ interstems produced a greater number of fruit and had a greater yield than the non-interstemmed controls. Neither fruit numbers nor yield on trees with interstems was significantly different from the non-interstemmed controls. If tree density were corrected for size, trees with ‘Conference’ interstems exhibited the highest production. Fruit size was significantly affected by interstem. Fruit size was not correlated with total yield. In Hood River trees with ‘Bosc’ interstems produced the largest sized fruit, while in Medford trees with ‘d’Anjou’ interstems produced the largest sized fruit. Yield efficiency (YE) was affected differently in the two locations. In Medford, interstemmed trees had less YE than the non-interstemmed controls; however, in Hood River the non-interstemmed control was intermediate in YE. Crop density was greater in trees with ‘Bartlett’ or ‘Conference’ interstems than in the non-interstemmed controls. | |
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