In the GEFR and NCB populations, entries differed significantly (P < 0.0001) for ear rot, fumonisin concentration, and silk date.
In the GEFR population, GE440, the parent line that was selected on the basis of previous information indicating that it possessed some resistance to fumonisin concentration, differed significantly from the susceptible parent line, FR1064, for mean fumonisin concentration within and across environments (Table 1).
One family in the GEFR population had significantly greater fumonisin concentration and one family had significantly greater ear rot than the susceptible parent, FR1064, across environments (Table 1).
In both populations and within every environment, except for ear rot in the Plymouth 2003 environment for the GEFR population, the mean ear rot and fumonisin concentration of the 10 lines with lowest mean fumonisin concentrations was significantly lower than the overall population means.
Heritabilities on an entry mean basis were moderately high to high for fumonisin concentration in both the GEFR ([h.sup.2] = 0.75, SE = 0.03) and NCB ([h.sup.2] = 0.86, SE = 0.02) populations.
In the GEFR population, genotypic correlation was very high ([r.sub.G] = 0.96, SE = 0.07), whereas the phenotypic correlation was only moderate ([r.sub.P] = 0.40; SE = 0.03).
In the GEFR population, when comparing indirect selection to direct selection, we predicted C[R.sub.fum]/[R.sub.fum] = 0.76.
Heritability on an individual plant basis was almost zero in the GEFR population, but substantially greater (0.21) in the NCB population.
The estimate of heritability from the GEFR population is also appropriate for predicting response to selection among B[C.sub.1][F.sub.1:2] families, in the absence of epistasis.
Due to the silk dates being significantly different among genotypes in the GEFR and NCB populations and the small but significant positive correlation only between silk date and ear rot in the both populations, it seems that maturity plays a real but minor role in ear rot resistance.
The GEFR population had a lower phenotypic correlation between ear rot and fumonisin concentration than the NCB population.
Since families in the GEFR population are segregating, the families with the least ear rot or least mean fumonisin concentration could have high fumonisin concentrations in some individual plots (Fig.