| 释义 |
‖ phototonus Bot.|fəʊˈtɒtənəs|
[mod.L., f. Gr. ϕῶς, ϕωτο- light (see photo-) + τόνος tension, tone.]
Name given by Sachs to the normal condition of sensitiveness to light in leaves and other organs, maintained by continued exposure to light, as opposed to the rigidity induced by long exposure to darkness. Hence phototonic |fəʊtəʊˈtɒnɪk| a., exhibiting phototonus; sensitive to light.
1875Bennett & Dyer tr. Sachs' Bot. 678 The power of movement in plants is lost when they have remained in the dark for a considerable time..; in other words, they become rigid by long exposure to darkness..; the exposure to light must continue for a considerable time..before the motile condition which I have termed ‘Phototonus’ is restored. Ibid. 790 Changes in the intensity of the light produce the same effect as irritants, but only on healthy phototonic plants; leaves which have become rigid from exposure to the dark show no irritability to variations in its intensity until they have again become phototonic from long-continued exposure to light. |