title: Phototropism, adaptation, and the light-growth response of Phycomyces.
abstract: Phototropic bending can be initiated without the transient changes in growth speed that characterize a light-growth response. The conditions required are a change from a symmetric to an asymmetric illumination pattern while the cell receives a constant radiant flux. Phototropism is thus basically a steady state process. It cannot be founded on differential light-growth responses as in Blaauw's theory. A possible model system for the unequal partition of growth during steady bending is discussed. The fact that light-growth responses show adaptation while phototropic bending does not follows from the different natures of the two responses.
mesh_terms: D000222:Adaptation, Physiological; D005658:Fungi; D008027:Light; D008954:Models, Biological; D008962:Models, Theoretical; D010775:Photic Stimulation; D018524:Phototropism; D010800:Phycomyces
keywords: FUNGI; LIGHT