Effects of pollination method and growing location on starch thermal properties of corn hybrids

Starch gelatinization and retrogradation properties of corn were studied to determine the effect of controlled (self) pollination versus noncontrolled pollination on analytical determinations, and the potential to eliminate the expensive and time-consuming step of self-pollinating before research screening of corn genotypes. Twenty-four hybrids were grown in two Iowa locations, Story City and Ames. At Story City, all hybrids received three pollination treatments: self-pollination; small-plot, open-pollination (representing corn from small test plots); and large-plot, open-pollination (representing corn from a farmer's field). Self-pollinated and small-plot, open-pollinated corn were grown in replicated two-row plots, whereas large-plot, open-pollinated corn was grown in unreplicated plots of 12.8 m x 8 rows. At Ames, the small-plot, open pollination treatment was not done. Starch was extracted from samples of corn harvested from each plot, and gelatinization and retrogradation properties were determined using differential-scanning calorimetry (DSC). Hybrids exhibited different starch gelatinization and retrogradation properties. Significant differences (P less than or equal to 0.05) in starch gelatinization and retrogradation properties occurred among pollination methods and between locations. Pollination method did not influence gelatinization enthalpy values, but onset temperature values for gelatinization, and range values for retrogradation differed significantly among pollination methods. At Ames, treatments gave different values for retrogradation enthalpy and percentage of retrogradation. Because of differences in some starch characteristics associated with pollination methods, self-pollination is recommended when growing samples in small plots for research purposes.