THERMAL PROPERTIES OF STARCH FROM EXOTIC BY ADAPTED CORN (ZEA MAYS L.) LINES GROWN IN FOUR LOCATIONS

Authors: LENIHAN, ELIZABETH - ISU; Pollak, Linda; WHITE, PAMELA - ISU

Submitted to: Cereal Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/21/2005
Publication Date: 9/1/2005
Citation: Lenihan, E., Pollak, L.M., White, P. 2005. Thermal properties of starch from exotic by adapted corn (Zea mays L.) lines grown in four locations. Cereal Chemistry. 82:683.689.

Interpretive Summary: We conducted a study using four growing locations to investigate the effect of environment on corn starch quality in inbred lines that we developed using exotic and adapted germplasm. The objective was to determine the thermal properties of starch, which affect cooking and storage characteristics, from four of our lines plus two Corn Belt lines grown in four different environments. We then used this information to further understand how growing conditions affect the starch quality; whether the growing conditions affect the lines in a similar fashion, and whether starch from the lines with exotic germplasm react similarly to Corn Belt lines to environmental conditions. Two of our lines, containing germplasm from Cuba, performed very well in all locations, and may be useful to improve the Corn Belt lines for their agronomic characteristics. The growing environment affected starch quality similarly for both our lines and the Corn Belt lines. The warmer location, in Missouri, produced starch with different cooking qualities than the cooler location, in Illinois. This was true for all genotypes. The other two locations, in Iowa, were very close to each other but differed in planting dates, soil type, and soil quality. One was located in a river bottom, where temperatures are often warmer than upland locations, plus planting date was later exposing the developing ear to warmer temperatures. The warmer location in Iowa produced starch with cooking qualities similar to Missouri for all lines, whereas the cooler Iowa location produced starch with cooking qualities similar to Illinois. These results are important to farmers growing specialty starch hybrids, the specialty starch industry, and their food industry clients, in that understanding environmental influences on corn starch may lead to targeting production locations for their ability to influence corn starch cooking quality. The results are also important to corn breeders and the seed industry in that the results can influence how breeders modify their selection and evaluation procedures when developing these specialty hybrids.

Technical Abstract: The effect of four growing locations (Ames, IA (2), Clinton, IL, and Columbia, MO) on the thermal properties of starch from 5 exotic by adapted corn inbred lines (Chis37, Cuba34, Cuba38, Dk8, Dk10) and two control lines (B73 and Mo17) were studied by using differential scanning calorimetry (DSC). The variations in thermal properties within locations were similar for the exotic by adapted lines and control lines. Missouri was the warmest location and generally produced starch with the greatest gelatinization onset temperature (ToG), the narrowest range of gelatinization (RG), and the greatest enthalpy of gelatinization ('HG). Illinois was the coolest location and generally resulted in starch with the lowest ToG, widest RG, and lowest 'HG. These differences were attributed to higher temperatures in Missouri during grain-filling months either increasing the amount of longer branches of amylopectin or perfecting amylopectin crystalline structure. The Ames 1 farm produced starch with thermal properties most similar to those of Illinois, whereas the Ames 2 farm produced starch with thermal properties most similar to those of Missouri. Ames 2, located near a river bottom where temperatures tend to be warmer, likely had temperatures most similar to those found in Missouri during grain-filling.