Increased food production and enhanced sustainability depend on improving nitrogen-use efficiency (NUE) of crops. Breeding for enhanced NUE can take advantage of doubled-haploid populations derived from parents differing in the trait. This study evaluated variation in photosynthetic parameters at various growth stages in 43 wheat genotypes (parents of the existing doubled-haploid mapping populations) under optimal and low (one-quarter of the optimal) N supply. For relative chlorophyll content, the genotype × N treatment interaction was significant at tillering, booting, pre-anthesis and anthesis. Genotypes with small differences in relative chlorophyll content between the two N supplies were CD87 at tillering and pre-anthesis, and Batavia at anthesis. Potential photochemical activity (Fv/Fm) was measured at tillering and anthesis. The genotype × N treatment interaction was significant in both growth stages. Based on net photosynthesis, stomatal conductance and intrinsic water usez efficiency, there was variable potential of the genotypes to cope with low N supply; significant differences were found among genotypes at ambient CO₂ and between N treatments at elevated CO₂ concentration (2000 µmol mol^–1) for all three parameters. Based on all studied parameters, a dissimilarity matrix was constructed, separating the 43 genotypes into four groups. Group 2 comprised 15 of the genotypes (Batavia, Beaver, Calingiri, CD87, Frame, Krichauff, Neepawa, Soissons, Spear, Stiletto, WAWHT2036, WAWHT2074, Westonia, Wilgoyne, Yitpi), characterised by small differences in relative chlorophyll content and Fv/Fm caused by different N supply at tillering and anthesis. These genotypes therefore appear to have relative tolerance to low N supply and a potential to be used in discerning the molecular basis of tolerance to low N supply.