Improved maize yields under low nitrogen (N) fertility is desired for both low- input production systems and also for judicious application of fertilizer nitrogen for a sustainable and environment friendly production systems. A key question in breeding for tolerance to low-N fertility is to what extent the performance of maize hybrids can be predicted on the basis of performance of their inbred lines under low-N supply. Past studies showed varied degree of correlations between line and hybrid performance under low-N fertility, ranging from weak to fairly strong relationship. We attempted to examine the impact of low-N supply on relationship between morpho-physiological traits and grain yield measured on inbred parents, all advance generation lines, and their single cross progenies. Reactions of various morpho-physiological traits, except days to anthesis (male flowering), differ significantly at low- and optimal level of N-fertility. Superiority of hybrid progenies over parental lines declined under low-N stress, which indicates that hybrids were comparatively more affected than lines due to low-N supply. Data on individual contributions of heterosis and performance of mid-parent showed that per se performance of lines was relatively more important factor in determining the hybrid performance under both the levels of N-supply. Correlations between various secondary traits and grain yield under both low and optimal-N fertility were moderate to strong in case of both parental lines and hybrids. However, it was comparatively stronger in case of hybrid progenies under low-N stress. Correlations between morpho-physiological traits of lines and hybrids, except for ear rots, were fairly strong and significant under both the level of N supply. The relationship between grain yield of mid-parent and hybrids was comparatively stronger under low-N fertility. Our findings suggest that performance of hybrid progenies under low-N fertility can be predicted to some extent on the basis of advance generation elite inbred parents with proven performance across N-supply.