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Competency for graviresponse in the leaf-sheath pulvinus of Avena sativa: onset to lossThe development of the leaf-sheath pulvinus of oat (Avena sativa L. cv. Victory) was studied in terms of its competency to respond to gravistimulation. Stages of onset of competency, maximum competency and loss of competency were identified, using the length of the supertending internode as a developmental marker. During the early phases in the onset of competency, the latency period between stimulus and graviresponse decreased and the steady state response rate increased significantly. When fully competent, the latency period remained constant as the plant continued to develop, suggesting that the latency period is relatively insensitive to quantitative changes (e.g., in carbohydrate or nutrient availability) at the cell level within the plant. In contrast, the response rate was found to increase with plant development, indicating that graviresponse rate is more strongly influenced by quantitative cellular changes. The total possible graviresponse of a single oat pulvinus was confirmed to be significantly less than the original presentation angle. This was shown to not result from a loss of competency, since the graviresponse could be reinitiated by increasing the presentation angle. As a result of the low overall graviresponse of individual pulvini, two or more pulvini are required to bring the plant apex to the vertical. This was determined to occur though the sequential, rather than simultaneous, action of successive pulvini, since a given pulvinus lost competency to gravirespond shortly after the next pulvinus became fully competent.
Document ID
20040089922
Acquisition Source
Headquarters
Document Type
Reprint (Version printed in journal)
Authors
Brock, T. G.
(University of Michigan Ann Arbor 48109, United States)
Kaufman, P. B.
Date Acquired
August 21, 2013
Publication Date
November 1, 1988
Publication Information
Publication: American journal of botany
Volume: 75
Issue: 11
ISSN: 0002-9122
Subject Category
Life Sciences (General)
Funding Number(s)
CONTRACT_GRANT: NAGW-34
Distribution Limits
Public
Copyright
Other
Keywords
Non-NASA Center
NASA Discipline Plant Biology
NASA Discipline Number 40-10
NASA Program Space Biology Research Associates
NASA Discipline Number 40-99
NASA Program Space Biology

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