Responses of wheat to vernalization and photoperiod

Authors:
  • JDJl Davidson
    Jl Davidson
  • KCKr Christian
    Kr Christian
  • DJDb Jones
    Db Jones
  • PBPm Bremner
    Pm Bremner
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Abstract
The effects of vernalization and photoperiod on times from planting of seedlings to ear emergence were measured in 68 Australian and 49 overseas varieties of wheat, comprising a broad spectrum of genetic material, in a glasshouse in Canberra (latitude 35¦S). Vernalization was carried out by growing germinated seedlings in the dark at 1-2¦C for 6 weeks. Long photoperiods (16 h) separated unvernalized plants into two distinct groups, corresponding to commonly recognized spring and winter types. Responses to vernalization were generally small under natural photoperiods (11-15 h), but much more pronounced in long photoperiods, particularly with winter wheats. In a second experiment, 24 varieties of wheat gave widely different responses to vernalization treatments. With 8 weeks' vernalization and long photoperiods, all varieties reached ear emergence within 66 days, but in some winter wheats 4 weeks treatment had little effect and 6 weeks gave incomplete vernalization. Under the conditions of these experiments, Australian wheats showed a wide range of responses to photoperiod and a narrow range of responses to vernalization compared with overseas varieties. The need to investigate the control of flowering time in obtaining varieties suited to the high-rainfall zone of Australia is discussed.