New Zealand Journal of Botany abstracts

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Flowering Responses to Daylength and Temperature in Dactylis glomerata L.

D. Wilson and R. G. Thomas*

Grasslands Division and Plant Physiology Division, Department of Scientific and Industrial Research, Palmerston North

Abstract Flowering responses of three clones of Dactylis glomerata L. to different day-length and temperature combinations and sequences were studied. These showed that:

(i) Induction was brought about by natural short days (lOh 10m, to 12h 30m) at all temperatures tested, but was more effective at day/night temperatures of 11.0/15.5°c than at 10.5/7.5°c or 18/15.5°c. Lower temperatures, averaging about 7.5/4°c, during short days, prevented later flowering altogether in one clone.

(ii) 18-hr days did not lead to induction.

(iii) Competence attained during induction at 10.5/7.5°c was lost in short days at temperatures of 18/15.5°c even though such conditions also led to competence.

(iv) Cool short days (10.5/7.5°c) led to both induction and strong initiation.

(v) Panicle initiation occurred in long days at both 10.5/7.5 and 18/15.5°c, but more proliftcally at the former temperature.

To explain these results an hypothesis is proposed that the development from the vegetative to the reproductive state involves a gradual progression from induction to initiation rather than two distinct stages. On this basis, warm long days destroy the early stages of induction and warm short days the later stages of induction.

(Received 11 June 1969) New Zealand Journal of Botany 9: 307-21.

PDF file of entire paper: medium quality (740K); (scanned from paper original: notes about this process)

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