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GrainGenes Reference Report: PGR-38-51

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Reference
PGR-38-51
Title
Effects of applying stem-shortening plant growth regulators to leaves on root elongation by seedlings of wheat, oat and barley: mediation by ethylene
Journal
Plant Growth Regulation
Year
2002
Volume
38
Pages
51-59
Author
Rajala A
Peltonen-Sainio P
Onnela M
Jackson M
Abstract
Summary: Several plant growth regulators (PGRs) commonly used in practical farming to restrict shoot height and control lodging were examined for their impact on root growth in naturally short or tall cultivars of barley (cvs. Kymppi and Saana), oat (cvs. Veli and Pal), and wheat (cvs. Mahti and Tjalve). The possible involvement of ethylene in the responses was also examined. Shoots were sprayed at the two-leaf stage with the gibberellin biosynthesis inhibitors Cycocel (chlormequat chloride) (CCC) or Moddus (Trinexapac-ethyl) (TE), or with the ethylene-releasing agent Cerone (ethephon) (ETH) at 0, 0.1, 1, 10 or 50 times the recommended agricultural rate (RR). Root elongation and ethylene production by roots or shoots were unaffected by CCC at all application rates or by TE at x0.1 or x1.0 RR. At x10 and x50 RR, TE was inhibitory to root extension but did not increase ethylene biosynthesis by these roots or the shoots. ETH at x0.1 or x1.0 RR did not affect root extension or ethylene production in roots or shoots. At all higher rates of application ETH stimulated ethylene production strongly in shoots and roots of all three species, while root elongation was retarded severely in barley, moderately in oat and only slightly in wheat. These differences in elongation response are attributed to differences in sensitivity to ethylene released by ethephon. Accordingly, root elongation in wheat was only slightly affected when ethylene gas was supplied at concentrations up to 100 ppm for 3 d. In contrast, root elongation in barley was strongly inhibited by ethylene, with oat demonstrating an intermediate responsiveness
Keyword
application rates
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