Tip growth patterns and growth rates of root hairs on ‘Tamar’ white clover (Trifolium repens L.) in low ionic strength culture solution

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 mm 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