KERNEL CHANGES IN A SHRUNKEN2 MAIZE POPULATION ASSOCIATED WITH SELECTION FOR INCREASED FIELD EMERGENCE

Ten cycles of simple mass selection for increased field emergence and kernel weight in a population of shrunken2 (sh2) maize affected various kernel and seedling traits. Ten of 29 variables measured were intercorrelated and were included in the first principal factor of a principal component, factor analysis. The eight variables in factor 1 that increased with cycles of selection were: emergence and kernel weight (the two selection criteria), plant height 41 days after planting (a measure of seedling vigor), uniformity of stand, total starch content per kernel, total carbohydrate content per kernel, concentration of starch, and starch content per kernel. The two variables in factor 1 that decreased were: conductivity of electrolytes that leached from imbibing seeds and symptomatic infection of kernels by fungi. Factor 1 was a ''seed and seedling quality'' factor. The other 19 variables formed five principal factors that primarily were ''sugar,'' ''pericarp,'' and ''asymptomatic fungal infection'' factors. These five factors, and the variables from which they were formed, were not affected by selection. These results suggest that seed and seedling quality factors can be improved by selection in a sh2 population without affecting sweetness or tenderness. These results also suggest that although selection for increased emergence and kernel weight lowered the incidence of symptomatic infection by fungi, the population was not improved specifically for resistance to Fusarium moniliforme Sheldon.