Thirteen new top crosses between B73 inbred line with some American and Egyptian inbred lines were made in 2012 season and evaluated with two commercial varieties (SC Pioneer 3084 and SC 10) under low (30 Kg N/fed) and normal (120 Kg N/fed) nitrogen fertilization rates in 2013 season to study the relative superior over the best commercial varieties and phenotypic correlations for morpho-physiological traits of maize under low and normal N conditions. Results showed that N-treatments mean squares were highly significant for all studied morpho-physiological traits and biological yield per plant. Also, mean squares of crosses were significant or highly significant for all studied traits under both and across N fertilization rates. The N-treatments × crosses interactions mean squares were insignificant for all studied traits, except each of biological yield per plant (Bio.Y/P), relative potential photosynthesis for biological yield (RPPbio.y) and Relative potential photosynthesis for straw yield (RPPs.y), which were highly significant. There were some new crosses manifested significant or highly significant positive or negative (desirable direction) relative superior percentages over both two commercial hybrids (SC Pioneer 3084 and SC 10) under both low and normal Nitrogen fertilization in most studied traits. For biological yield per plant and relative potential photosynthesis for biological yield (RPP_BIO.Y), results showed that two crosses (B73X CML103 and B73X TZI8) recorded positive significant relative superior over both commercial hybrids SC Pioneer 3084 and SC 10 under both low and normal N conditions. The phenotypic correlation coefficients varied from moderate to strong correlations between grain yield plant^-1 and biological yield plant^-1 and most of studied morpho-physiological traits, suggesting that, in general, to increase grain yield plant^-1, selection should be carried out for these traits, especially; biological yield plant^-1, low ear leaf angle (erect leaf), stem diameter (thick stalks), as well as physiological traits i.e. relative potential photosynthesis for biological yield (RPP_BIO.Y) and straw yield (RPP_St.Y) under both low and normal N conditions. The two crosses B73X CML103 and B73X TZI8 exhibit improved morpho-physiological adaptation to low N fertilization and better management of its internal N under normal N rate, and consequently this study recommend these crosses for large scale evaluation and commercial production.