Plant Growth Regulation

, Volume 38, Issue 1, pp 51–59

Effects of applying stem-shortening plant growth regulators to leaves on root elongation by seedlings of wheat, oat and barley: mediation by ethylene

Authors

  • Ari Rajala
    • Department of Plant Production, Section of Crop HusbandryUniversity of Helsinki
  • Pirjo Peltonen-Sainio
    • Department of Plant Production, Section of Crop HusbandryUniversity of Helsinki
  • Marko Onnela
    • Department of Plant Production, Section of Crop HusbandryUniversity of Helsinki
  • Michael Jackson
    • IACR – Long Ashton Research Station, Department of Agricultural SciencesUniversity of Bristol, Long Ashton
Article

DOI: 10.1023/A:1020924307455

Cite this article as:
Rajala, A., Peltonen-Sainio, P., Onnela, M. et al. Plant Growth Regulation (2002) 38: 51. doi:10.1023/A:1020924307455

Abstract

Several plant growth regulators (PGRs) commonly used in practicalfarming to restrict shoot height and control lodging were examined for theirimpact 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. Shootswere sprayed at the two-leaf stage with the gibberellin biosynthesis inhibitorsCycocel (chlormequat chloride) (CCC) or Moddus (Trinexapac-ethyl) (TE), or withthe ethylene-releasing agent Cerone (ethephon) (ETH) at 0, 0.1, 1, 10 or 50times the recommended agricultural rate (RR). Root elongation and ethyleneproduction by roots or shoots were unaffected by CCC at all application ratesorby TE at ×0.1 or ×1.0 RR. At ×10 and ×50 RR, TE wasinhibitory to root extension but did not increase ethylene biosynthesis bytheseroots or the shoots. ETH at ×0.1 or ×1.0 RR did not affect rootextension or ethylene production in roots or shoots. At all higher rates ofapplication ETH stimulated ethylene production strongly in shoots and roots ofall three species, while root elongation was retarded severely in barley,moderately in oat and only slightly in wheat. These differences in elongationresponse are attributed to differences in sensitivity to ethylene released byethephon. Accordingly, root elongation in wheat was only slightly affected whenethylene gas was supplied at concentrations up to 100 ppm for 3d. In contrast, root elongation in barley was strongly inhibitedbyethylene, with oat demonstrating an intermediate responsiveness.

BarleyEthyleneOatsPlant growth regulatorsRoot growthWheat
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© Kluwer Academic Publishers 2002