Figure 4.
Effect of nitrate on vacuolar pH in maize root segments following a switch to anoxia. A series of in vivo 31P NMR spectra were recorded before, during, and after a 2-h period of oxygen deprivation, and the vacuolar pH was inferred from the chemical shift of the vacuolar Pi signal. The growth and incubation conditions are defined in the legend for Figure 1, and each pH value is the mean of between three and six replicate measurements ±se. The switch to anoxia occurred at time zero, the dotted lines connect the normoxic and anoxic pH values, and the se values for the −/+ experiment are omitted for reasons of clarity.