Scion/Rootstock Interactions Determine Tree Size of Ten Asian Pear Scion Cultivars on Five Old Home x Farmingdale Rootstocks

Abstract

The influence of five Old Home x Farmingdale (OHF) clonal rootstocks, OHF 51, OHF 97, OHF 217, OHF 282 and OHF 333 on tree size with Asian near scion cultivars, ‘20th Century’ ‘Chojuro,’ ‘Hosui,’ ‘Kikusui,’ ‘Niitaka,’ ‘Okusankichi,’ ‘Seigyoku,’ ‘Shinko,’ ‘Shinseiki’ and ‘Tse Li’ was examined after 10 years in an experimental orchard in central Washington state. The effect of rootstock on tree size varied among scion cultivars. Within the cultivars, ‘Chojuro,’ ‘Hosui,’ ‘Niitaka’ and ‘Seigyoku,’ trunk cross-sectional areas (TCA) were similar regardless of rootstock, but ‘Hosui’ trees were significantly larger than ‘Niitaka’ and ‘Seigyoku’ trees, which were significantly larger than ‘Chojuro.’ Within ‘Tse Li,’ which had the largest TCAs, OHF 333 produced larger trees than OHF 282 and OHF 217. ‘Okusankichi’ trees, which were generally the same size as ‘Hosui,’ were significantly larger on OHF 217 and OHF 97 than on OHF 333. ‘Kikusui’ trees, which were generally similar in size to ‘Niitaka’ and ‘Seigyoku,’ were larger on OHF 217, OHF 97 and OHF 282 than on OHF 333. ‘20th Century,’ which was similar in size to ‘Chojuro’ and ‘Shinseiki,’ appeared to be the cultivar most sensitive to rootstock. ‘20th Century’/OHF 217 were significantly larger than trees on OHF 97 and OHF 282, which were larger than trees on OHF 51. ‘Shinseiki’/OHF 97 were larger than trees on OHF 333. Contrary to research with some European pear scions, consistent trends did not emerge from this research that would allow a general prediction of the relative influence of these 5 OHF clonal rootstocks on Asian pear tree size.