Hormones - Research Article from Macmillan Science Library: Plant Sciences

This encyclopedia article consists of approximately 7 pages of information about Hormones.
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Major Effects of the Principal Plant Growth Hormones

Gibberellins (Gas).

Produced in young leaves, developing seeds, and probably in root tips, the biologically active GAs, such as GA1 and GA3, move in shoots without polarity and at a slower rate than IAA down the stems where they cause elongation. In roots they show root-tip toward root-base polar movement—the opposite of IAA. Their effect on stem elongation is particularly striking in some plants that require exposure to long days in order to flower. In such plants the stem elongation that precedes flowering is caused by either long days or active GAs and is so fast that it is called bolting. A similar association of light effects and active GAs is found in seeds that normally require light or cold treatment to germinate. GAs can substitute for these environmental treatments. In cereal seeds, GA, produced by the embryos, moves...

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This section contains 2,098 words
(approx. 7 pages at 300 words per page)
Buy the Hormones Encyclopedia Article
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Macmillan Science Library: Plant Sciences
Hormones from Macmillan Science Library: Plant Sciences. Copyright © 2001-2006 by Macmillan Reference USA, an imprint of the Gale Group. All rights reserved.
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