Hj. Hawkins et al., Root respiratory quotient and nitrate uptake in hydroponically grown non-mycorrhizal and mycorrhizal wheat, MYCORRHIZA, 9(1), 1999, pp. 57-60
Oxygen and CO2 fluxes were measured in hydroponically grown mycorrhizal and
non-mycorrhizal Triticum aestivum L. cv. Hano roots. The NO3- uptake of th
e plants was used to estimate the amount of root respiration attributable t
o ion uptake. Plants were grown at 4 mM N and 10 mu M P, where a total and
viable mycorrhizal root colonisation of 48% and 18%, respectively, by Glomu
s mosseae (Nicol. and Gerd.) Gerd. and Trappe (BEG 107) was observed. The O
-2 consumption and NO3- uptake rates were similar and the CO2 release was h
igher in mycorrhizal than in nonmycorrhizal wheat. This resulted in a signi
ficantly higher respiratory quotient (RQ, mol CO2 mol(-1) O-2) in mycorrhiz
al (1.27 +/- 0.13) than in non-mycorrhizal (0.79 +/- 0.05) wheat. As the bi
omass and N and P concentrations in mycorrhizal and non-mycorrhizal wheat w
ere the same, the higher RQ resulted from the mycorrhizal colonisation and
not differences in nutrition per se.