New Zealand Journal of Crop and Horticultural Science abstracts
Effect of hand pinching and plant growth regulators
on seed production of field grown hybrid dahlia
S. PHETPRADAP*
J. G. HAMPTON1
M. J. HILL
Seed Technology Centre
Department of Plant Science
Massey University
Palmerston North, New Zealand
*Present address: Maejo Institute of Agricultural Technology, Chiangmai,
Thailand.
Abstract The effects of hand pinching above node four on the
main stem and the application of the plant growth regulators paclobutrazol and
chlormequat chloride on seed production of field grown hybrid dahlia `Unwins
Mixed' were investigated over two seasons at the same site. Pinching reduced
the spread of flowering and resulted in seed heads at approximately the same
height above ground level because of the promotion of lateral branch length,
but did not increase seed yield. Seed yield per plant was significantly
increased following the application of chlormequat chloride at 1.5 kg a.i./ha
at stem elongation in the first season, and by paclobutrazol applied at 1.0 kg
a.i./ha at the appearance of the first visible flower bud in both seasons, the
former through the production of more seed heads/plant, and the latter through
a significant increase in seeds/seed head in one season and seed heads/plant in
the following season. Other seed yield components did not differ among
treatments. Plant growth retarding effects were transitory and floral
development and flower numbers were not altered by the plant growth regulators.
Although results were inconsistent, chemical manipulation of this hybrid dahlia
shows promise for seed production and warrants further investigation.
Keywords dahlia; Dahlia pinnata x Dahlia
coccinea; seed production; plant growth regulators; paclobutrazol;
chlormequat chloride; hand pinching
New Zealand Journal of Crop and Horticultural Science, 1994, Vol. 22:
313-320
0114-0671/94/2203-0313 $2.50/0 (c) The Royal Society of New Zealand
1994
PDF file of entire paper: medium quality (567K); (scanned from paper original: notes about this process)
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