HERITABILITY OF PRODUCT FRACTIONS FROM WET-MILLING AND RELATED PROPERTIES OF MAIZE GRAIN

Wet milling is an important use of maize (Zea mays L.) grain produced in the USA, and commercial wet millers and hybrid seed companies are i ncreasingly interested in hybrids which have enhanced milling properti es. Because of the cumbersome nature of traditional laboratory wet-mil ling procedures, relatively little information is available regarding inheritance of wet-milling product fractions. In this study, the inher itance of maize wet-milling product fractions was evaluated in grain o f 40 full-sib families from a Design I mating (20 males; two females p er male) and a newly developed, rapid, laboratory milling procedure. T he narrow-sense heritability estimate of male-family means for the sta rch fraction was 0.73. Predicted gain from selection with a conservati ve heritability estimate was 7.4 g kg(-1) per cycle for the starch fra ction. Phenotypic and genetic correlation coefficients between the wet -milling starch fraction and initial starch concentration, measured by near-infrared reflectance, were significant (0.79 and 0.89, respectiv ely). Significant phenotypic and genetic correlation coefficients were observed between a wet-milling index and an index based on near-infra red reflectance. Relative rankings of check hybrids were significantly different between these two indices. Results from this study indicate d product fractions from maize wet milling are heritable, and thus mod ifiable through selection. Genetic correlation coefficients suggested that selection for increased starch extractability from wet milling co uld be accomplished by using near-infrared reflectance to measure star ch concentration. Changes in hybrid rank among met-milling and near-in frared reflectance indices suggested that final selections of candidat e hybrids for specific milling applications should be based on actual wet-milling evaluation.