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Thermal Starch Properties in Corn Belt and Exotic Corn Inbred Lines and Their Crosses¹

¹Journal Paper J-17167 of the Iowa Agriculture and Home Economics Experiment Station, Ames, IA. Projects 3082 and 3396. ²Research geneticist, USDA-ARS Corn Insects and Crop Genetics Research Unit, Dept. Agronomy, Iowa State University, Ames, IA 50011. Corresponding author. E-mail: lmpollak@iastate.edu ³Professor, Dept. Food Science and Human Nutrition, Iowa State University.

More knowledge is needed about variability of starch functional traits in adapted and exotic germplasm and possible genetic effects of these traits before conducting rigorous inheritance studies and breeding programs for starch quality. We studied and compared the range of variability for starch functional traits in a set of Corn Belt inbred lines with a set of exotic inbred lines from Argentina, Uruguay, and South Africa. Reciprocal hybrids of some of the lines within each set were compared with their parents. Functional traits were examined by using differential scanning calorimetry on starch extracted from single kernels of genotypes. The set of Corn Belt lines had a wider range of values for most traits than did the set of exotic lines. For both sets of lines, the maximum value for peak height index was as high as that previously reported for the waxy endosperm mutant. Although the Corn Belt lines exhibited a wider range of values for range of retrogradation than the exotic lines, the exotic lines showed a wider range of values for percentage retrogradation. Hybrid values were not consistently higher, lower, midpoint, or similar with respect to the values of their parents. This was true regardless of germplasm type or functional trait. Reciprocal cross values showed trends suggesting reciprocal differences, although there was no trend suggesting greater effect of the female parent. These traits seem to be controlled by many modifying effects in addition to major effects. Results indicate that sufficient variability exists in Corn Belt germplasm to conduct breeding and inheritance studies effectively and that there should be potential for breeding for functional traits.