Abstract
The objectives of this study were to determine whether there is variability in the protein–nutritional composition of grains among single-cross, triple-cross, and double-cross hybrids and OPVs and different sowing dates and to develop models for amino acid prediction based on the CP content. A total of 773 grain samples from four maize cross-types cultivated with ten sowing dates were evaluated by Near Infrared Reflectance Spectroscopy. Descriptive statistics were applied and simple linear regression models were developed for protein-nutritional traits for different cross-types and sowing dates. Principal component analysis was used to group data on the protein-nutritional composition of grains and meteorological variables, by cross-types and by sowing dates. Open-pollinated varieties of maize had the highest means of crude protein, lysine, methionine, cystine, threonine, tryptophan, valine, isoleucine, leucine, histidine and arginine in the grains, compared to single-cross, triple-cross and double-cross hybrids regardless of the sowing date. Methionine, cystine, threonine, tryptophan, valine, isoleucine, leucine, histidine and arginine in maize grains can be predicted from their crude protein with high precision in single-cross, triple-cross and double-cross hybrids and open-pollinated varieties.