• Circadian basis for the photoperiodic response in the male blackheaded bunting (Emberiza melanocephala)

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    • Keywords


      Blackheaded bunting; photoperiod; circadian; rhythm; light; dark cycle; external coincidence model

    • Abstract


      Short day (6 hr light in a 24 hr cycle (ld 6 ∶ 18)) inhibits growth and development of the testes in male blackheaded buntings, whereas the same (6 hr) nonstimulatory photoperiods in a 36 hr cycle (ld 6 ∶ 30) induce complete testicular recrudescence and development. In another experiment of 24 hr cycles, using the same (6 hr) main photoperiod, testes were stimulated when the dark period was interrupted by light at 12 to 13 hr after the onset of basic photoperiod (ldld 6 ∶ 6 ∶ 1 ∶ 11). The results appear to conform to the tenets of the external coincidence model.

    • Author Affiliations


      Vinod Kumar1 P D Tewary1

      1. Department of Zoology, Banaras Hindu University, Varanasi - 221 005, India
    • Dates


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