Relations between lammas shoot elongation and flowering of male and female flowers in Pinus densiflora seedlings.

フラッシュを開始する前の2月20日, 3月2,12,22日の各日に, アカマツの1年生苗を最低温度を18℃に調整したガラス室へ搬入し, 5月21日に再び野外へ戻した。その後, これらの苗の頂端に形成された冬芽を対象に, 各区の土用芽の発生率, 12月下旬の冬芽長, 翌春の雄花と雌花の開花数を調べた。この結果, 土用芽は, 2月20日区などの加温開始時期の早い区において多く発生し, これらの区の個体では連鎖的に休眠期の冬芽長が大となった。さらに, これらの区の個体では翌春の雄花の数が野外のものよりも多くなったが, 雌花の数は少なくなった。このように, 土用芽の発生にともなう冬芽長の増大は雄花の分化を促進したとみられた。しかし, 過多に伸長した冬芽では雄花数が多くならなかった。また, いずれの区でも雄花と雌花の双方を着生した個体はほとんどみられなかった。Potted, two-year-old Pinus densiflora seedlings grown under outdoor condition were carried into the greenhouse, which had an adjusted minimal temperature of 18℃, on February 20th, March 2nd, 12th, and 22nd before budding. They were again returned to the outdoors on May 21st. Afterwards, we determined the percentages of lammas shoot formation, the lengths of winter buds at the end of December, and the numbers of male and female flowers in the next spring. As heating treatments in the greenhouse initiated earlier, the percentages of lammas shoots and the lengths of terminal buds became greater. The number of the male flowers in the heated seedlings became more abundant than that of outdoor seedlings, while the number of the female flowers became fewer. The elongation of the terminal buds as the result of the lammas shoot formation seemed to be related to the differentiation of the male flowers. However, the number of the male flowers was infrequent in excessively-elongated buds. Moreover, few seedlings had both male and female flowers in any treatment