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The Initiation of an Endogenous Rhythm Affecting Flower Bud Formation in Pharbitis nil
Author(s) -
PARASKA JOHN R.,
SPECTOR CALVIN
Publication year - 1974
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1974.tb03727.x
Subject(s) - pharbitis nil , rhythm , endogeny , seedling , stimulus (psychology) , circadian rhythm , period (music) , biology , period length , photoperiodism , botany , neuroscience , psychology , medicine , physics , endocrinology , mathematics , discrete mathematics , acoustics , psychotherapist
When seedlings of Pharbitis nil are presented with an inductive dark period at varying times, they show a circadian fluctuation in the number of flower buds initiated. This study determines if this fluctuation is due to the plant's perception, at the time of the inductive dark period, of either a rhythmic, external, environmental stimulus or of an endogenous rhythm. Using experimental designs in which the time of planting, the time of seedling emergence from the soil, and the time at which the presentation of an inductive dark period are varied, this fluctuation in flower bud formation is shown to be due to an endogenous rhythm initiated or synchronized by some event associated with the emergence of the seedlings from the soil. The results are inconsistent with the hypothesis that the plants are responding to rhythmic external stimuli.