Inheritance of phosphorus concentration in maize grain: Gene action and correlated traits

Maize (Zea mays L.) hybrids with a concentration of total phosphorus in the grain (P-Gr) that more closely matches the dietary needs of beef cattle (Bos taurus) for this element are needed in the USA. This research was undertaken to determine the type of gene action controlling this trait and the correlation of P-Gr to other traits. Partial dominance for low P-Gr was observed in crosses between S, families selected for high and low P-Gr. However, high P-Gr values of all entries evaluated in this research relative to the desirable level of P-Gr suggested a need to breed for low P-Gr on both sides of the pedigree. Positive phenotypic (0.54) and genotypic (0.65) correlations were observed between P-Gr and the concentration of protein in the grain (Pro-Gr) among 177 unselected S-1 families evaluated across two years. The presence of outliers suggested that P-Gr Could be lowered while maintaining or increasing Pro-Gr. Strong associations were not observed between P-Gr and concentration of P in aboveground plant tissue at several stages of growth. High P-Gr S, families had significantly better seedling vigor scores than low S-1 families, but the difference was only 0.6 on a 9-point scale. A negative association was observed between grain yield and P-Gr. However, on a percentage basis, the difference in yield between high and low P-Gr groups was less than the difference in P-Gr. The results of this research indicated that improving maize grain as a feed for cattle by reducing P-Gr while not adversely affecting grain yield or Pro-Gr should be possible.