New Zealand Journal of Agricultural Research abstracts
Tip growth patterns and growth rates of root hairs on ‘Tamar’ white clover
(Trifolium repens L.) in low ionic strength culture solution
D. A. Care
J. R. Crush
AgResearch
Ruakura Research Centre
Private Bag 3123
Hamilton, New Zealand
email: debbie.care@agresearch.co.nz
Abstract A flow-through, low ionic strength nutrient
solution system was used in four experiments to establish elongation rates,
time to maximum length of individual root hairs, and temporal changes in length
in small populations of root hairs in a genotype from a population of cv
‘Tamar’ white clover (Trifolium repens L.) previously selected for
long root hairs. Young root hairs showed pronounced pulsatile growth, with
relative extension rates increasing four-fold over the basal rate. In older
hairs the amplitude and frequency of the pulsatile growth declined as hairs
approached their full length. At the average root hair elongation rate over
all hairs and experiments (3.3 μm h–1) it would take 4.5 days
for the longest root hair observed (363 μm) to reach its final length, and
2.4 days to reach the population mean root hair length of 190 μm. Re-analysis
of the data using a Bayesian technique gave an estimate of 2.0 days for root
hairs to reach the population mean length. The results suggest that root tips
of this plant used in experiments on root hair demography should be at least
5 days old to ensure that representative root hair populations are being
used.
Keywords pulsatile growth; root hairs; tip growth; Trifolium
repens; ultradian rhythm; white clover
A03024; Received 14 April 2003; accepted 26 September 2003; online publication
date 26 February 2004
New Zealand Journal of Agricultural Research, 2004, Vol. 47: 67–73
0028–8233/04/4701–0067 © The Royal Society of New Zealand 2004
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