NO 2 flux into leaves of nitrate reductase-deficient barley mutants and corresponding changes in nitrate reductase activity

Abstract

To investigate the role of nitrate reductase in determining the flux of NO 2, mutants of Hordeum vulgare L., which are deficient in nitrate reductase activity (NRA) to varying degrees, were exposed to NO 2. This resulted in an inhibition of NRA in shoots of most of the mutants tested. Furthermore, the flux of NO 2 into leaves, net water vapor loss from the leaves and stomatal conductance to water vapor were similar in the mutants tested despite significant differences in nitrate reductase activity. Fluxes of NO 2 appeared to be mainly dependent on stomatal conductance although some “internal” conductance to NO 2, representing the transfer of ions into the cell and between storage and metabolic pools, may also be involved.