ABSTRACT Quality protein maize (QPM) (Zea mays L.) is primarily used for food in countries of tropical and sub-tropical regions where maize is the main source of protein. Although its cultivation in temperate regions is hampered by residues of exotic germplasm, it could be beneficial for use in livestock feeds as it was shown that substitution of standard maize with QPM can improve livestock characteristics and decrease dietary lysine supplementation. The aim of this study was to test 11 QPM hybrids obtained by crossing adapted QPM inbred lines for their performance in field trials in 2 yr at four locations, as well as to determine their relevant biochemical components. The main reason for rejecting nine QPM hybrids was low grain yield, standard hybrids had higher yields on average for 37.8%. Hybrid ZPQPM6 had good agronomic characteristics, but its biochemical components were nonsignificantly different from the standard hybrid. Only hybrid ZPQPM13 met necessary criteria, grain yield comparable with standard hybrids, high tryptophan content in different environments (average 0.083%) and hard endosperm (average score 1.87). Lysine content, measured after mercantile production, was 0.44%. Quality index, although below the QPM threshold (which is 0.80%) was significantly higher (p < 0.05) in ZPQPM13 in comparison with standard hybrid, indicating improved nutritional quality of the protein. The results indicated that presence of exotic germplasm in these QPM hybrids is a consequential difficulty and that in their parental inbred lines at least one more backcross with temperate germplasm should be done to select better adapted QPM.

ABSTRACT A pilot experiment was undertaken in order to examine high oil populations of maize (Zea mays L.) to be used as pollinators in TopCross blends with commercial ZP341 standard hybrid. Five high oil populations (HOPs) from the Maize Research Institute (MRI) gene bank were chosen for this research, according to their high grain oil content, synchrony between silking of ZP341 and anthesis of the populations and good agronomic performances in 2012. Selfing of ZP341 and HOPs, as well as crosses of ZP341 cmsS sterile × HOPs were carried out in 2013. Oil content, fatty acid composition, protein and tryptophan content, and physical characteristics of the obtained kernels were measured. Four HOPs showed significant positive influence on the oil content in the TopCrosses (TC), 16.85 g kg−1 on average. Oleic acid, which is the principal monounsaturated fatty acid, was significantly lower in all HOPs and all TCs, while selfed ZP341 had almost twice the average value typical for standard maize. However, this decrease in TCs was in a narrow range from 1 % (in TC-3) to 5 % (in TC-4) and the oleic content of TCs was on average higher by 60 % compared to the typical standard maize. Different favorable and unfavorable significant changes were detected in fatty acid compositions, protein and tryptophan contents and physical kernel properties for each potential TC combination. Results indicate differences in gene effects present in different TC combinations and underscore the need to examine each potential TC blend by conducting similar simple experiments.