Plant protecting and regulating compositions – Plant growth regulating compositions – Stunting or dwarfing agent
Patent
1994-05-12
1996-07-02
Clardy, S. Mark
Plant protecting and regulating compositions
Plant growth regulating compositions
Stunting or dwarfing agent
504182, 504299, 504320, 504348, 504353, A01N 3708, A01N 4308, A01N 4500
Patent
active
055322069
DESCRIPTION:
BRIEF SUMMARY
This application is a continuation (filed under 35 USC 371) of PCT application PCT/AU92/00426, filed Aug. 14, 1994.
This invention relates to a method of treating plants or plant tissues (including cuttings, roots, bulbs, corns, tubers, rhizomes and seeds) in order to induce a desired tissue morphology and/or a desired physiological state.
Numerous phytoactive substances are known which are used in agricultural and horticultural practice in order to promote desired physiological effects in higher plants. Such effects include promotion of flowering, weed control, inhibition of stem elongation (dwarfing), improvement of hardiness, promotion of rooting and inhibition of root or shoot growth in germinating seeds. Many available phytoactive substances have undesirable side effects and may give rise to toxic residues which tend to pollute the environment.
Naturally occuring gibberellins have found extensive use in agriculture and horticulture and can, for example, be used as components of compositions for promoting flowering. The so-called effector gibberellins (GAs), including GA.sub.1 and GA.sub.3, produce stem elongation in many plants and while this may in certain circumstances be desirable, often the converse is the case and it is preferable to retard stem elongation in order to produce dwarf plants. The control of flowering and stem elongation of higher plants is economically desirable for a number of reasons, including, but not restricted to enhancing earliness of flowering, ensuring uniformity of flowering, increasing the number of flowers produced, and reducing the height of the plant, thereby making it more resistant to falling over, or breakage, and also making it easier to train (i.e. orchard trees).
The literature makes it apparent that certain members of the gibberellin class of molecules will effectively promote flowering in many, but not all higher plants. However a major drawback to the use of those gibberellins which have been reported to promote flowering is the increased shoot and stem growth (elongation) caused by application of such gibberellins. Further, these overt side effects may make the plant more susceptible to being damaged, or falling over (being lodged) as a result of rain, hail or snow or simply as a result of sheer overgrowth. Additionally, it is known that application of many gibberellins to woody angiosperm species is known to be deleterious to next year's flowering. That is to say application of a gibberellin in order to enhance fruit set or fruit quality may inhibit the following year's flower crop.
Reducing the shoot growth in a flowering plant is extremely useful in many circumstances. First it makes the plant more resistant to adverse weather conditions in the field, such as wind, rain, hail and snow. Secondly, it makes the plant more compact, more stocky, and more resistant to falling over (technically known as "lodging") as a result of the aforementioned weather conditions and/or as a result of heavy fruit or seed or grain production. Thirdly, in orchard situations a more compact nature of the shrub or tree is extremely valuable for a variety of reasons, including ease of tending the tree, picking the fruit, applying other treatments and reducing the necessity to prune the tree or shrub. Also, shoot growth resulting either from the presence of high levels of endogenous gibberellins, or induced by gibberellins applied to the plant, can compete with growth and development of fruit, seed or grain, thereby reducing the final yield.
A high concentration of endogenous effector gibberellins can be undesirable in plants which have been subjected to conditions likely to cause physiological damage. Thus the presence of effector gibberellins such as gibberellins GA.sub.1 and/or GA.sub.3 in recently transplanted trees and woody shrubs can give rise to reduced hardiness resulting in diminished survival.
We have now developed a procedure for promoting a desired tissue morphology and/or physiological state in a higher plant, which comprises applying to the plant an amount of a C-16,17
REFERENCES:
Crozier et al "The biological activity of 26 gibberrellins . . . " Can. J. of Bot. 48: 867-877. 1970.
Phinney et al "Dwarf Mutants in Maize--The Gibberrellin Biosynthetic Pathway" in M. Bopp, ed. Plant Growth Substances 1985.
Sponsel, V. "Gibberellin Biosynthesis and Metabolism", in P. Davies, ed. Plant Hormones and their Role in Plant Growth and Development. 1987.
Mander, L. "The Chemistry of Gibberellins: an Overview" Chem Rev. 92: 573-612. 1992.
Evans Lloyd T.
King Roderick W.
Mander Lewis N.
Pearce David W.
Pharis Richard P.
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