Nitrate induction in spruce: an approach using compartmental analysis

Abstract

Using 13NO(Formula presented.)-efflux analysis, the induction of nitrate uptake by externally supplied nitrate was monitored in roots of intact Picea glauca (Moench) Voss. seedlings over a 5-d period. In agreement with our earlier studies, efflux analysis revealed three compartments, which have been identified as surface adsorption, apparent free space, and cytoplasm. While induction of nitrate uptake was pronounced, NO(Formula presented.)fluxes in induced plants were decidedly lower and the induction response was slower than in other species. Influx rose from 0.1 μmol·g−1·h−1 (measured at 100 μM [NO(Formula presented.)o) in uninduced plants to a maximum of 0.5 μmol·g−1h−1 after 3 d of expos..