森林立地54(1),1〜5 2012
Jpn J For Environ
54 (1), 1–5, 2012
Positive and negative phototropism in Schizophragma
hydrangeoides and Parthenocissus tricuspidata
Shogo Kato1, Toshinari Kanematsu1,
Nobumitsu Kawakubo1, Akira Komiyama1
1Faculty of Applied Biological Sciences, Gifu
University
We investigated phototropism in two liana species with different-climbing habits. The vines Schizophragma hydrangeoides and Parthenocissus tricuspidata use roots and adhesive-tendrils to climb, respectively. While these two species showed similar behaviors when exposed to light, illumination experiments detected very interesting responses when different stages of growth were studied. Short creeping shoots exhibited positive phototropism. Long creeping shoots appeared to show negative phototropism. This change in phototropism according to shoot length implies these climbing vines have adapted habits useful for climbing host trees. Soon after germination, their short shoots need to seek light for rapid growth, but their shoots need to explore the host trees after a certain period of growth. The base of a large host tree, the starting point for climbing, is usually in relatively dark forest floors. The vine’s ability to change from positive to negative phototropism would be an essential habit for both types of vines which climb the planar surfaces of their hosts.
Key words : adhesive-tendril climber, creeping shoot, phototropism, root climber, vine
加藤正吾，兼松俊成，川窪伸光，小見山章：イワガラミとナツヅタの正と負の光屈性．森林立地54:1-5,2012.
異なる登攀様式を示す，付着根型つる植物のSchizophragma hydrangeoidesと吸盤型つる植物のParthenosissus tricuspidata の光屈性を調べた。両種に側面から光を照射し，シュートの屈曲のようすを伸長とともに観察した。両種とも，光の照射に対して，シュート長が短いと正の光屈性を示し，シュート長が長くなると負の光屈性を示した。両種の短いシュートは，充分な光合成生産を行うために，正の光屈性を示す必要性があるかもしれない。しかしながら，シュートが伸長すれば林床で相対的に暗い支持ホストの根元を探索しなければならない。したがって，正から負の光屈性に変わることは，支持ホストの平面構造を主に登攀する付着根型と吸盤型のつる植物にとって重要な性質である。
キーワード：つる植物，吸盤型つる植物，光屈性，付着根型つる植物，匍匐シュート