Interrelations among Protein, Lysine, Oil, Certain Mineral Element Concentrations, and Physical Kernel Characteristics in Two Maize Populations

The interrelationships among whole kernel protein, lysine, oil, P, K, Mg, Fe, and Zn concentrations and physical kernel characteristics were determined in a heterozygous opaque-2 population and a homozygous opaque-2 maize (Zea mays L.) population. Compared to normal kernels the opaque-2 kernels were higher in lysine, P, K, Mg, Fe, and Zn concentrations. However, on a kernel weight or kernel volume basis, the opaque-2 kernels were significantly greater only for lysine, K, and Zn. Our results indicated that the opaque-2 gene, or closely linked genes, had a direct influence on K and Zn content as well as on lysine content. The correlation of the differences between the normal and opaque-2 kernels for percent lysine and percent Zn was positive and significant. This relationship may indicate that modifier genes that are influencing the effect of the opaque-2 gene on lysine concentration may also be influencing the effect of the opaque-2 gene on Zn concentration in a similar manner. Several significant correlations were detected between percent lysine and the mineral element concentrations, but none were of sufficient magnitude to be of value as a selection criteria for lysine content. Percent lysine was not correlated with kernel weight or volume but was negatively correlated with kernel density. The coefficients for the correlation between percent lysine and percent protein were +0.50 and +0.70, respectively, for the normal and opaque-2 kernels in the heterozygous population and +0.83 for the homozygous opaque-2 population. The magnitude of these correlation coefficients indicated a rather strong tendency for lysine concentration to increase as protein concentration increased, especially in the opaque-2 kernels. Protein concentration was found to be the best selection criteria for lysine concentration except for possibly the lysine concentration per se.