Summary
Photorefractory male yellow-throated sparrows (Gymnorhis xanthocollis) were subjected to six resonance light cycles, consisting of 6 h basic photophase coupled with scotophases of longer durations (in cycles of 12 (6L∶6D) h, 24 (6L∶18D) h, 36 (6L∶30D) h, 48 (6L∶42D) h, 60 (6L∶54D) h and 72 (6L∶66D) h). Termination of photorefractoriness was evident in cycles of 24, 48 and 72 h, but not in 12, 36 and 60 h. The results are consistent with the ‘external-coincidence’ model (Bünning hypothesis) and suggest that endogenous circadian rhythmicity is involved in the termination of photorefractoriness.
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This investigation was supported by a UGC grant to PDT and BHU to PMT.
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Tewary, P.D., Tripathi, P.M. Circadian periodicity in termination of photorefractoriness in the yellow-throated sparrow. Experientia 41, 1350–1351 (1985). https://doi.org/10.1007/BF01952090
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DOI: https://doi.org/10.1007/BF01952090