ウンシュウミカン'青島温州'の樹体内デンプン含量の時期的変化と冬季の根中デンプン含量による着花量予測(栽培管理・作型)  [in Japanese] Seasonal Changes in Starch Content and Forecasts of the Amount of Blossom based on the Content of Starch in the Root of Satsuma Mandarin cv. 'Aoshima Unshu' Trees(Crop Production & Cropping Type)  [in Japanese]

着果量の異なるウンシュウミカン'青島温州'について,秋季から春季の樹体内のデンプン含量(葉,枝,根)を調査したところ,いずれの部位も不成り年樹で成り年樹より高い値で推移した.また,根のデンプンは他の器官より早くから蓄積しはじめ,不成り年樹で11月から,成り年樹で収穫後の1月からそれぞれ含量が多くなった.着果量の違いが樹体内のデンプン含量に最も反映する部位と時期は,11〜2月の根であった.このことから,これが冬季の炭水化物の栄養状態を把握するために適する時期および部位と考えられた.デンプン含量が増加した原因を解明するため,光合成速度を測定した.その結果,ウンシュミカンは冬季においても光合成を行っていたことから,根中デンプン含量の増加は,光合成に起因していると考えられた.一方,生産現場における'青島温州'の冬季(12月)の根中デンプン含量と翌年の着花量との関係を調査したところ,根中デンプン含量と翌年の葉花比との間には負の相関関係がみられ,着花量の予測が可能と考えられた.

Seasonal changes in the starch contents of leaves, shoots and roots, and the photosynthetic rate of the alternate-bearing 'Aoshima Unshu' Satsuma mandarin were investigated from fall to spring. Off-year trees showed higher starch levels in the leaves, shoots and roots from fall to spring than on-year trees. Accumulations of starch were observed earlier in roots than in other organs. The starch contents in the roots of off-year trees increased from November and the starch contents of on-year trees increased from January in Shizuoka. The organs showing the strongest concentrations of starch were the roots, and the months were November to February. Photosynthetic activity of Satsuma mandarin was observed in winter, indicating that photosynthesis by the leaves plays a role in starch accumulation in the roots during winter. Relationships of the negative correlation were found between the starch content of the roots in December and the numbers of flowers (number of leaves/number of flowers) the following spring. These results show that the numbers of flowers can be forecast from the content of roots that were collected in the winter of the same season.