During
the light reaction, a surplus of nicotinamide adenine dinucleotide hydrogen phosphate (NADPH) is also
produced, which is not completely consumed during the assimilation of CO2. Nitrate reduction in leaves
represents a NADPH sink in addition to that mentioned in the paragraph above. This sink for NADPH
consumption is not available to plants supplied with ammonium (Fig. 2). As shown by Salsacet al.