Corn Grain Density Characterized by Two Specific Gravity Techniques

Grain quality of corn (Zea mays L.) is an important breeding consideration, hindered by the limitations of visual selection. This exploratory laboratory study sought to develop preliminary information on two simple techniques for estimating kernel density, which is assumed to relate to grain hardness. The two are the floater technique (percentage of floating kernels in a salt solution) and the conventional technique (specific gravity as related to water). Kernel density increased with selection for low percentage floaters during early inbreeding. Narrow‐sense heritability of percentage floaters was 0.73. Density of F1 seed was closely related to that of the female parent; e.g., 19 crosses averaged 32.8% floaters and the 19 female parents as inbreds averaged 31.2% floaters, whereas the reciprocal crosses averaged 97.6% floaters and the common female parent averaged 99.8% floaters. Flat kernels averaged 31.6% floaters and round kernels averaged 43.0% in one experiment, and averaged 12.4 and 24.7% floaters, respectively, in another. Density of three grade sizes varied relative to genotype. A test solution of specific gravity 1.275 was satisfactory for general evaluation, but higher levels were useful for additional determinations. The two techniques were correlated at about −0.8 (P < 0.01)