Table 5.

Root extension and estimation of distance and time to the end of the growth zone or root hair emergence

			Onset of root hair emergence or end of growth zone
Plant species and root type	Growth conditions	Rate of tip extension (mm d−1)	Distance from tip (mm)	Time since tip arrival (d)
Wheat seminal root*	Loose, 15 °C	24·5	8·6	0·35
	Hard, 15 °C	8·16	1·4	0·17
Wheat seminal root†	Loose, 15 °C	35	5·15	0·15
	Loose, 7 °C	10·1	5·5	0·54
Maize‡	29 °C	69·6	12·5	0·18
	16 °C	25	12·3	0·5
Maize§	Vermiculite, moist (3·7 %; −0·03 MPa), 29 °C	74·4	10·5	0·14
	Vermiculite, Dry (0·1 %; −1·6 MPa), 29 °C	26·4	6	0·22
Arabidopsis primary root¶	Agar	8·6	1·3	0·15

^*Watt et al. (2003); onset of root hair emergence measured.

^†Refshauge (unpubl. res.); onset of root hair emergence measured.

^‡Pahlavian and Silk (1988); end of growth zone measured, length growth zone not related to extension rate.

^§Sharp et al. (1988); end of growth zone measured.

^¶van der Weele et al. (2003); end of growth zone from Fig. 3; see also their fig. 7 for other species.