Departmental Bulletin Paper カキ新品種‘八秋’

薬師寺, 博  ,  山崎, 安津  ,  小林, 省藏  ,  東, 暁史  ,  杉浦, 裕義  ,  佐藤, 明彦

(1)  , pp.27 - 35 , 2017-03-30 , 国立研究開発法人 農業・食品産業技術総合研究機構 , National Agriculture and Food Research Organization (NARO)
1.‘八秋’は,独立行政法人農業・食品産業技術総合研究機構果樹研究所ブドウ・カキ研究拠点(現 国立研究開発法人農業・食品産業技術総合研究機構果樹茶業研究部門ブドウ・カキ研究領域)において,2005 年に‘平核無’成木の枝変わりとして発見された八倍体(2n =120 = 8x)のわい性で早生の不完全渋柿である.‘平核無’と‘中谷早生’を対照品種として特性調査を実施し,2013 年に‘八秋’(はっしゅう)と命名し,公表された.2015 年3月に種苗法に基づき,登録番号第23900 号として品種登録された.2. 果実の成熟期は早生であり,育成地では‘平核無’とほぼ同時期の10 月下旬であった.果実重は育成地では平均81 gと小さく,‘平核無’の約1/4 であった.果皮色は橙色である.CTSD 炭酸ガス脱渋で‘平核無’および‘中谷早生’と同様に容易に脱渋し,日持ちは10 日程度で‘平核無’と同程度であった.肉質は密で,果肉硬度は‘平核無’および‘中谷早生’と同程度に柔らかく,果汁の量は多い.育成地における脱渋後の平均糖度は16.3%であった.3. 種子形成力があり,果実当たり2.8 個の完全種子(種子重:1.2 g)を含有する.4. へたすきおよび条紋は発生しないが,果頂裂果は20%程度の果実で発生した.破線状および黒点状の汚損果が23%発生した.5. 樹勢は中で,樹姿は斜上性である.休眠枝は黄褐色で,短く,節間長も短い.開花期は‘平核無’と同時期であり,雌花は小さい.雌花の着生は多く,雄花は着生しない.葉の形は卵形であり,葉の大きさは小さい.早期落果は少なく,後期落果はほとんど発生しない.
‘Hasshu’ is a pollination-variant astringent (PVA) type of Japanese persimmon (Diospyros kaki Thunb.) cultivar released by Japan’s National Agriculture and Food Research Organization (NARO) Institute of Fruit Tree Science (NIFTS) in 2013. ‘Hasshu’, a dwarf bud sport that originated from‘Hiratanenashi’, was discovered in Akitsu, Higashihiroshima, Hiroshima Prefecture in 2005. It is octoploid (2n = 120 = 8x). The cultivar was registered in 2015 as No. 23900 under Japan’s Plant Variety Protection and Seed Act.The fruit ripens in late October, similar to ‘Hiratanenashi’, and about a month after ‘Nakataniwase’, at NIFTS (in Higashihiroshima city). The fruit is relatively flat, and averages 81 g in weight, which is about one-quarter the weight of ‘Hiratanenashi’. The skin is orange at harvest time. The shelf life of ‘Hasshu’ fruit after treatment with carbon dioxide gas to remove astringency, was 10 days, which is the same as that of ‘Hiratanenashi’. The flesh is as soft, dense, and juicy as ‘Hiratanenashi’ and ‘Nakataniwase’. The mean soluble solids content in the juice after removing the astringency is 16.3% (°Brix), which is comparable to those of ‘Nakataniwase’ and ‘Hiratanenashi’.‘Hasshu’ produced an average of 2.8 normal seeds (with a seed weight of 1.2 g) per fruit, versus none in the other cultivars. Although fruit cracking at the calyx end is rare, fruit cracking at the stylar end occurred in 20% of the fruits. The proportion of fruit with partly darkened skin averaged 23.3%, versus 6.7% in ‘Hiratanenashi’ and ‘Nakataniwase’. There were no shallow concentric cracks in the fruit’s skin.The tree is moderately vigorous, with a shape intermediate between spreading and upright. The shoot and internode lengths were significantly shorter than those of ‘Hiratanenashi’ but similar to those of ‘Nakataniwase’. The leaf shape was ovate and its leaf area was significantly smaller thanthose of ‘Hiratanenashi’ and ‘Nakataniwase’. ‘Hasshu’ bore many smaller female flowers than those of ‘Hiratanenashi’ and ‘Nakataniwase’ in late May. There was little physiological fruit drop in both the early stage (June to July) and the late stage (August and later).

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