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1)1954年から1958年にかけ, NAA散布によるりんごの摘果効果並びにその機構について実験調査するところがあった.2)供試材料には祝, 旭, 紅玉, ゴールデンデリシヤスが用いられ.NAAは三共製薬のα-ナフタレン酢酸ソーダ塩が用いられ.濃度は10〜20ppmで, 散布には小型手押噴霧器が用いられた.3)NAA散布によって摘果効果のあがる時期は開花期で, 蕾期および幼果期ではやや濃度を高めなければ効果が得られない.4)NAA散布による摘果程度は対照区の1/2〜1/3が適当と考えられるが, この程度の成績をうるための濃度は一般的に次の様であった.祝-15ppm, 旭-20ppm, 紅玉-30ppm, ゴルーデンデリシヤス-40ppm.5)NAAの影響は樹勢の強い場合には現われず, 弱い場合に現われた.6)3年枝花叢は2年枝花叢よりNAA散布による花叢そのものの落下は少なかったが花叢内果実の落果は多かった.7)花叢中の中心果と側果との落果率の比率は常に前者に少なく, 後者に大であるが, NAA散布によってもこの傾向は変らなかった.8)旭, 紅玉についての摘果効果を示すNAAの実用的濃度20ppm溶液散布では旭では1果をとどめるものが80〜90%, 2果をとどめるものが10〜20%であり, 紅玉では1果をとどめるものが60%, 2果をとどめるものが30%であった.9)落果の波相には2つの山が見られ, 第1の山は6月上旬, 第2の山は6月中旬で, NAA散布区の山は第1の山の現われが対照区より幾分おくれるが常に山が高い.10)人工発芽床における花粉の発芽試験では, NAA添加によって置床当初数時間の発芽は抑制されたがその後の発芽はよく, 花粉管の伸長もよく, 対照区におとらなかった.11)NAA散布により果実の発育は散布後10日間位はやや緩漫となり, そのまま発育せず落果するものと, 対照区の果実と同様に発育

1) The influence of fruit thinning with NAA sprays on apple fruit production and the thinning mechanisms caused by NAA were studied from 1954 to 1958. 2) For these tests, New Summer Permain, McIntosh, Jonathan, and Golden Delicious aplles were used. As a thinner, NAA- sodium salt of α-naphthalene acetic acid was employed at concentrations of 10-40 ppm applying by handy sprayer on flowers or young fruits. 3) Best thinning results were obtained when NAA applied just in bloom and slightly higher concentrations were needed to use at the pink stage or young fruit stage. 4) Fruit thinning up to half or one third of fruits of unthinned trees was favorable. For this adequate thinning, NAA sprays at 15 ppm on New Summer Permain, 20 ppm on McIntosh, 30 ppm on Jonathan, and 40 ppm on Golden Delicious were cnsidered to be beneficial. 5) It was observed that NAA treatment had a marked thinning effects on trees of poor vigor and not on vigorous trees. 6) The dropping of 3-year-old clusters by NAA spraying was fewer than that of the clusters of 2 years old but dropping flowers in a cluster of 3 years old occurred highly. 7) Dropping percentage of the center fruits in a cluster was always not higher than that of lateral fruits in a cluster, and this findings was also observed after treatments of NAA. 8) By applying NAA at a concentration of 20 ppm on McIntosh and Jonathan varieties, it was found in McIntosh apples that one fruit in a cluster was produced by 80-900f a total fruit set and two fruits in a cluster was odtained by 10-20%.0 In Jonathan variety it was observed that 601024730130f a total fruit set had one fruit in a cluster and 30-0.000000or two fruits in a cluster. 9) Variations of fruit dropping in the season was noticed ; the first peak of dropping occurred in early June, and the second one appeared in middle June. By applications of NAA the first fruit dropping in early June occurred little later but dropping rate was always higher than that of unsprayed controls. 10) By addition of NAA solution to agar-sugar germi

source:The technical bulletin of Faculty of Horticulture, Chiba University