Possibility of Wild Blueberry Shashanbo (Vaccinium bracteatum Thunb.) as a Rootstock for Cultivation of Northern Highbush Blueberry in Warm Region

Abstract

The possibility of using wild blueberry Shashanbo (Vaccinium bracteatum Thunb.) as a rootstock for cultivating northern highbush blueberry in a warm region was investigated. The survival ratios of three different cultivars ('Berkeley', 'Bluecrop', and 'Earliblue') grafted on 3-year-old seedlings of Shashanbo plants were 85.7 to 100%. Furthermore, 41 cultivars included in highbush blueberries and rabbiteye blueberries were successfully grafted on seedlings of Shashanbo rootstock. There were no signs of incompatibility even four years after grafting, and anatomical observations of graft unions supported this result. The shoot growth and fruit weight of 'Earliblue' grafted on seedlings of Shashanbo rootstock were significantly higher than those of plants on their own roots. However, the shoot growth of 'Earliblue' grafted on rooted cuttings of rabbiteye blueberries ('Homebell' and 'Tifblue') was significantly higher than that of those on seedlings of Shashanbo rootstock. In addition, there were no differences in concentrations or component ratio of sugars and organic acids on any rootstock. These findings suggest that Shashanbo has graft compatibility with blueberry and that seedlings could be used as a rootstock for cultivating northern highbush blueberries in southern Kyushu. Key Words：graft compatibility, organic acids, soil adaptability, sugars キーワード：接ぎ木親和性，糖，土壌適応性，有機酸 緒 言 ブルーベリー（Blueberries）は，ツツジ科（Ericaceae）ス ノキ属（Vaccinium）に分類される北アメリカ原産の，落葉 性 お よ び 常 緑 性 の 低 木 ま た は 半 低 木 性 の 果 樹 で あ る （Vander Kloet, 1988） ．これらは 6 種に大別されるが，通常， 栽培ブルーベリーと呼ばれるのはハイブッシュブルーベ リー（Vaccinium corymbosum L.）とラビットアイブルーベ リー（V. ashei Reade）の 2 種であり（Eck・Childers, 1966） ， 前者は，低温要求量の多少と樹高により北部，南部および 半樹高の 3 グループに分けられる． 現在栽培されているブルーベリーは，主に米国で育成さ れたものであるが， 我が国にも 19 種のスノキ属植物が自生 している（玉田，1996） ．これまで，日本に自生しているス ノキ属植物は， 栽培や品種改良に利用されてこなかったが， 近年になって小松ら（2003）はクロマメノキ（V. uliginosum 2005 年 7 月 25 日 受付．2006 年 4 月 18 日 受理．