Heterosis in compositional, physical, and wet-milling characteristics of hybrids from exotic introgressed by adapted inbred lines in corn

Abstract

Corn (Zea Mays L.) is the main crop in the United States and starch is the most important product derived from corn kernels. Use of corn by the processing industry has steadily increased and hybrids with high grain yield and higher starch, protein, or oil content are available to growers. However, utilization of exotic germplasm in maize breeding programs does not represent more than 3% of the genetic base currently in use to produce corn hybrids grown in the United States. In addition to yield trial evaluations to determine the agronomic performance of new corn cultivars, it is necessary to determine the physical, compositional, and milling characteristics that could provide added value for processing and increase the usefulness of new inbred lines and hybrids. The present study was conducted to determine whether Corn Belt lines introgressed with exotic materials from Argentina, Chile, Uruguay, Cuba, and Florida have appropriate wet-milling characteristics. Ten lines from the Germplasm Enhancement of Maize project with different starch content yields, three commercial inbred lines, and two public inbred lines (B73 and Mo17) were analyzed using both Near-Infrared Transmitance (NIT) and a 100-g wet-milling procedure. Statistical differences (P<0.05) were found for yield of the wet-milled fractions (starch, fiber, gluten, and germ). AR227 and CU562, two lines of exotic origin, had similar or better starch yield and starch recovery than B73 and the other adapted inbred lines, which indicates that these lines can potentially be used to improve the proportion of extractable starch present in the kernels of their hybrids. Residual protein levels in the starch and gluten fractions were in the range of 0.26-0.32% and 3845%, respectively. The starch yield of exotic corn lines from wet milling correlated positively with starch content and was negatively correlated with protein content of the corn kernels. Oil content in the germ varied from 50 to 60%. Our results indicate that the use of exotic germplasm to improve the wet-milling characteristics in a corn breeding program may enhance genetic diversity available for breeding.