Table 1.

Oxygen consumption per unit of elongation and volume expansion of unimpeded (0 kPa) and impeded (15 kPa) roots, using data from root growth and oxygen consumption experiments

Root characteristic	0 kPa	15 kPa	% increase
Extension rate (mm h−1)	1·1	0·3
O2 consumption of growing tissues* (µmol h−1)	200	100
O2 consumption per unit extension (µmol mm−1)	180	330	80
Rate of volume growth (mm3 h−1)	0·93	0·83
O2 consumption of growing tissues† (µmol h−1)	200	270
O2 consumption per unit volume growth (µmol mm−3)	215	325	50

^*0–10 mm in unimpeded roots (0 kPa); 0–4 mm in impeded roots (15 kPa).

^†0–10 mm zone in both treatments.