The light growth response of Phycomyces

K. W. Foster, E. D. Lipson

Research output: Contribution to journalArticlepeer-review

46 Scopus citations


With the help of an automated tracking system we have studied the characteristics of the transient light growth response of Phycomyces. The response shows a sharply defined latency. The Q10 of the reciprocal latency is 2.4. Response patterns at different peaks of the action spectrum are the same. The gradual variation of response magnitude over a wide range of adapted intensities parallels that of phototropism. The responses to saturating stimuli exhibit a strong oscillation with a constant period of 1.6 min and variable damping. The growth responses to sinusoidally varying light intensities show a system bandwidth of 2.5 × 10-8 Hz. The linear dependence of phase shift on frequency is largely attributable to the latency observed with pulse stimuli. In the high intensity range a previously suspected increase of the steady-state growth rate with intensity has been confirmed. The light growth responses of mutants selected for diminished phototropism have been investigated. Many of these mutants have sizable but grossly distorted growth responses.

Original languageEnglish (US)
Pages (from-to)590-617
Number of pages28
JournalJournal of General Physiology
Issue number5
StatePublished - Nov 1 1973

ASJC Scopus subject areas

  • Physiology


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