Canola, borage and coriander were grown in a growth chamber with treatments of increasing rates of added nitrogen. Dry matter yield was measured at the early-flowering stage. Both borage and coriander had a lower potential dry matter yield and a corresponding lower nitrogen requirement than canola. Based on this experiment, borage and coriander fertilizer nitrogen could be recommended at about 30% less than the rates for canola. All of the crops responded strongly to added nitrogen up to their maximum yield
potential. Measurements of leaf tissue nitrate, using an anion resin exchange membrane extraction, proved to be an accurate predictor of potential plant growth and a potential tool for fertilizer management.