Abstract
When 14C-paclobutrazol, a gibberellin synthesis inhibitor, was applied to different parts of actively-growing M.26 apple rootstock shoots it was translocated acropetally when applied to the young stem and, to a lesser extent, from the youngest unrolled leaf. Paclobutrazol was not translocated out of leaf laminae, shoot tips or from one-year-old wood but translocation occurred out of a treated petiole into the attached leaf. No basipetal translocation was detected. This translocation pattern suggested movement through the xylem.
Localised application of paclobutrazol caused a reduction in shoot extension and leaf production when the young stem or shoot tip were treated; the effect decreased as older parts of the stem were treated. Treatment of laminae or petioles had only a slight effect on shoot extension and treatment of one-year-old wood was ineffective. Combined treatment of the shoot tip plus young stem was similar in effect to treatment of the complete shoot.
It is suggested that paclobutrazol exerts its effects on shoot growth by inhibiting gibberellin biosynthesis in the shoot tip and the expanding leaves.
The findings contribute to an understanding of the requirements for efficient orchard application of foliar sprays of paclobutrazol.
Similar content being viewed by others
References
Balasubramanyan S (1984) Diastereomers and enantiomers of paclobutrazol: Their preparation and biological activity. Pestic. Sci. 15:296–302
Barrett JE and Bartuska CA (1982) PP333 effects on stem elongation dependent on site of application. Hort Sci 17:737–738
Crafts AS and Yamaguchi S (1964) The autoradiography of plant materials. California Agricultural Experiment Station Extension Service Manual No. 35:143
Dicks JW (1980) Mode of action of growth retardants. In: Clifford DR and Lenton JR, eds. Recent Developments in the Use of Plant Growth Retardants. British Plant Growth Regulator Group Monograph No. 4:1–14
Graebe JE and Ropers HJ (1978) Gibberellins—Sites of formation. In: Letham DS, Goodwin PB and Higgins TJV, eds. Phytohormones and Related Compounds—A Comprehensive Treatise Vol. 1, pp 173–178. Amsterdam, Oxford, New York: Elsevier/North-Holland Biomedical Press
Hedden P, Ward DA, Andrews PR, Ward GC and James S (1983) Gibberellin metabolism and the mode of action of plant growth regulators. Rep. E. Malling Res. Stn for 1982, 147–148
Herrington PJ, Mapother HR and Stringer A (1981) Spray retention and distribution on apple trees. Pestic. Sci. 12: 515–520
Horrocks DL (1974) Applications of Liquid Scintillation Counting, p 182. New York: Academic Press
Lever BG, Shearing SJ and Batch JJ (1982) PP333—new broad spectrum growth retardant. Proceedings 1982 British Crop Protection Conference—Weeds 1: 3–10
McComb AJ (1964) The stability and movement of gibberellic acid in pea seedlings. Ann Bot 28: 669–687
Miller SS (1982) Growth and branching of apple seedlings as influenced by pressure-injected plant growth regulators. HortSci 17:775–776
Quinlan JD (1981) New chemical approaches to the control of fruit tree form and size. Acta Hort 120:95–106
Quinlan JD and Richardson PJ (1984) Effect of paclobutrazol (PP333) on apple shoot growth. Acta Hort 146:105–111
Sterrett JP (1985) Paclobutrazol: A promising growth inhibitor for injection into woody plants. J Amer Soc Hort Sci 110:4–8
Tukey LD (1983) Vegetative control and fruiting on mature apple trees treated with PP333. Acta Hort 137:103–109
Williams MW and Edgerton LJ (1983) Vegetative growth control of apple and pear trees with ICI PP333 (paclobutrazol) a chemical analog of Bayleton. Acta Hort 137:111–116
Zweig G, Yamaguchi S and Mason GW (1961) Translocation of C14-gibberellin in red kidney bean, normal corn and dwarf corn. Advanc Chem Ser 28:122–134
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Richardson, P.J., Quinlan, J.D. Uptake and translocation of paclobutrazol by shoots of M.26 apple rootstock. Plant Growth Regul 4, 347–356 (1986). https://doi.org/10.1007/BF00024934
Received:
Revised:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00024934