A microcomputer method for continuous measurement,recording and control of ion activity during nitrate uptake byLolium perenne

A microprocessor controlled apparatus is described which can measure, control and record nitrate uptake byLolium perenne in nutrient solution, comparing seven selection lines in duplicate. Nutrient solution flowed at 1 min⁻¹, and linear response was found from 10⁻¹ to 10⁻⁴ M NO ₃ ⁻ . Uptake rates for Lolium were between 10⁻⁵ and 10⁻⁴ M NO ₃ ⁻ , plant⁻¹, h⁻¹, which agreed with previous, manually determined, rates, ‘Overshoot’ in nitrate dosing, which was a problem with manual systems, was eliminated. Nitrate concentration was controlled (±3%) in modified Hoagland’s solution.