Respiration of field-grown loblolly pine roots as influenced by temperature and root type

Respiration was determined manometrically for 136 samples of field-grown loblolly pine roots collected over a period of several months. Mean [Formula: see text] values ranged from 0.028 to 3.68, depending upon root size, type, mycorrhizal condition, and temperature. Roots with vigorous, active mycorrhizae respired more than twice as fast, on a dry weight basis, than roots with less vigorous mycorrhizae or no mycorrhizae. Unsuberized root-tip meristems respired several times faster than roots of any other type.