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THIRD POSITIVE (C‐TYPE) PHOTOTROPISM IN THE AVENA COLEOPTILE 1
Author(s) -
Blaauw O. H.,
BlaauwJansen G.
Publication year - 1970
Publication title -
acta botanica neerlandica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.871
H-Index - 87
eISSN - 1438-8677
pISSN - 0044-5983
DOI - 10.1111/j.1438-8677.1970.tb00178.x
Subject(s) - coleoptile , tonic (physiology) , phototropism , irradiation , chemistry , physics , optics , biology , endocrinology , biochemistry , blue light , nuclear physics
SUMMARY The third (C‐type) 1 response results from a tonic and a tropistic effect of the irradiation. The Bunsen‐Roscoe reciprocity law applies to the tonic as well as to the tropistic component. A simple dependence on the duration of the stimulus does not exist, but is simulated by the time interval required for effectuation of the tonic component. It is concluded that the C‐type curvature is identical with the first positive curvature, but is evoked by larger doses of unilateral light because of a desensibilisation of the coleoptiles by the tonic effect of the long unilateral irradiation itself. This desensibilisation process takes a minimum period of 4 resp. 15 minutes to be effective with red‐preirradiated or dark‐cultivated coleoptiles, respectively.