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This article in CS

  1. Vol. 17 No. 5, p. 797-799
    Received: Feb 24, 1977



Red and Far-Red Light Effects on Climbing in Phaseolus vulgaris L.1

  1. Paul J. Kretchmer,
  2. J. L. Ozbun,
  3. Stuart L. Kaplan,
  4. D. R. Laing and
  5. D. H. Wallace2



Growth habit of some Phaseolus vulgaris L. lines is influenced by geographic and seasonal environment, complicating their geographical adaptation. This study was undertaken to determine if this morphological instability is a photoperiodic or photomorphogenic response. Three P. vulgaris L. lines that changed from indeterminate bush to indeterminate climbing under different environments in Columbia, South America, and one line that did not were grown in controlled environments. Photoperiods of 12 vs. 18 hours did not affect the time at which climbing occurred or the percentage of plants that climbed. However, plants climbed 2 to 4 days earlier and the percentage of climbing plants increased 4.5 to 20-fold when the dark period of either the 12 or 18-hourphotoperiod was interrupted with 15 rain of red light. This indicates that the change in morphology was due to the reddight interruption and not to the effective length of the dark periods that such an interruption created, implying a photomorphogenic rather than a photoperiodic response. The morphological instability caused by a night break of red light was nullified when the red light was followed by a far-red irradiation, suggesting that the morphological instability was controlled by phytochrome.

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