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Water content and the conversion of phytochrome regulation of lettuce dormancyIn an effort to determine which biological reactions can occur in relation to the water content of seeds, the regulation of lettuce seed dormancy by red and far red light was determined at various hydration levels. Far red light had an inhibiting effect on germination for seeds at all moisture contents from 4 to 32% water. Germination was progressively stimulated by red light as seed hydration increased from 8 to 15%, and reached a maximum at moisture contents above 18%. Red light was ineffective at moisture contents below 8%. Seeds that had been stimulated by red light and subsequently dried lost the enhanced germinability if stored at moisture contents above 8%. The contrast between the presumed photoconversion of phytochrome far red-absorbing (Pfr) to (Pr) occurring at any moisture content and the reverse reaction occurring only if the seed moisture content is greater than 8% may be explained on the basis of the existence of unstable intermediates in the Pr to Pfr conversion. Our results suggest that the initial photoreaction involved in phytochrome conversion is relatively independent of water content, while the subsequent partial reactions become increasingly facilitated as water content increases from 8 to 18%.
Document ID
20040089642
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Vertucci, C. W.
(Cornell University Ithaca, New York 14853, United States)
Vertucci, F. A.
Leopold, A. C.
Date Acquired
August 21, 2013
Publication Date
January 1, 1987
Publication Information
Publication: Plant physiology
Volume: 84
ISSN: 0032-0889
Subject Category
Life Sciences (General)
Distribution Limits
Public
Copyright
Other
Keywords
Non-NASA Center
NASA Discipline Number 40-10
NASA Program Space Biology
NASA Discipline Plant Biology

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