カキの生理的落果防止に関する研究 I : 落果波相および分離層形成について(農学部門)

カキの生理的落果を防止するための基礎的資料をえる目的で, 次郎および平核無成木を供試し1964年5月より11月にわたって, 自然落果および受粉の有無による落果状況を観察し, あわせて落果時の分離層の分化形成過程について調査した。1)その結果, 自然落果についてはほぼ3波相を示したが, 落果期前半にかなり多くの落果がみられ, 開花後ほぼ1ヶ月間の累積落果率は次郎で57%, 平核無では77%におよんだ。2)受粉は次郎では著しく落果を抑制したが, 平核無についても落果を軽減する効果が認められた。3)結果枝上の着果数の多少による落果状況は一定の傾向が認められなかった。4)落果時の分離層の形成については, 若い花蕾では未分化の状態であったが, 果梗と萼の接合部で開花期ごろより緻密な数層の小細胞からなる分離組織が接合部外側より内側に向って漸次分化しはじめ, 花後7日∿10日ごろには10数層の細胞からなる完全な分離層が形成された。この形成過程は受粉, 無受粉および受粉萼片除去の処理によって相違が認められなかった。果実と萼の接合部では分離層の形成が認められなかった。The studies were carried out to inquire the mechanism on the physiological dropping of Japanese persimmon fruit. This experiments were investigated on the time of fruit dropping and abscission layer formation in 1964. As the materials, the mature trees of Jiro and Hiratanenashi were used. The results of the experiments are summarized as follows : 1. The natural fruit dropping begins after petal fall, and continues to late July. After that time, the fruit dropping does not occur in Jiro and Hiratanenashi. In these performances of early dropping, the time of fruit dropping shows three times, but many fruit dropping were observed in former term of dropping season. Fruit dropping was controlled by the pollination, and the fruit dropping rate does not differ in bearing shoots which have been born different number of fruit. 2. Abscission layer was formed between fruit stalk and calyx. The differentiation begins from the outside between fruit stalk and calyx at the flowering time, and it was finished about one week after full bloom. Abscission layer formation was not concerned to the pollination, and the small cell arranges precisely in its layer. It seems that the fruit dropping occurs by the maceration of abscission layer cells. Otherwise, abscission layer was not formed between fruit and calyx