This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Bevington, J. M. Articles by Hoyle, M. C. Search for Related Content PubMed PubMed Citation Articles by Bevington, J. M. Articles by Hoyle, M. C. Agricola Articles by Bevington, J. M. Articles by Hoyle, M. C.

Articles

Phytochrome Action during Prechilling Induced Germination of Betula papyrifera Marsh ¹

Merrill C. Hoyle

Department of Biology, Moravian College, Bethlehem, Pennsylvania 18018, Northeastern Forest Experiment Station, Forest Service, U. S. Department of Agriculture, Durham, New Hampshire 03824, Forestry Sciences Laboratory, Durham, New Hampshire 03824

Seeds of paper birch (Betula papyrifera Marsh.) were induced to germinate by prechilling at 3 C or by red light. The light requirement was mediated by phytochrome and the action of phytochrome during prechilling was investigated. Red irradiation (R) prior to prechilling markedly enhanced the effectiveness of the prechilling treatment in inducing subsequent germination at 18 C. Reversal of this enhancement by far-red irradiation (FR) was more effective when FR was supplied after a 1-week prechill treatment than after a 2-week treatment. The R enhancement effect exhibited a sharp drop as prechilling temperature was increased from 5 to 7 C. This decline is consistent with a membrane phase transition at about 7 C where Pfr action is diminished by a loss in sensitivity of its receptor sites. Although phytochrome action was observed during prechilling treatments, the seeds failed to germinate at prechilling temperatures. Therefore, it was concluded that while potentiation of germination by Pfr occurred during prechilling, some other reaction(s) leading to radicle protrusion requires higher temperatures. In one seed source loss of germination potential was observed with protracted storage at 3 C. This was prevented by R supplied during the prechilling treatment. Taken collectively the data suggest that action of phytochrome during prechilling is accentuated in these seeds by two factors: (a) an increase in the sensitivity (or number) of Pfr receptor sites; and (b) preservation of Pfr by deferment of thermal reversion.

¹ Preliminary work was supported by a Grant-in-Aid of Research from the Society of Sigma Xi, a research grant from the American Philosophical Society, and a development award from the Moravian College Committee for Development and Research to J.M.B. A cooperative research agreement between the United States Forest Service and Moravian College supported much of this work.