Relative Storability of High-Oil and Bt Corn Hybrids Compared to Conventional Hybrids

The objectives of this study were to compare relative storability for five pairs of normal–oil content and high–oil content corn (Zea mays) hybrids, and for five pairs of conventional and Bt corn hybrids, stored at 20.C (68.F) and at two different moisture values (19% and 22%, wet basis). Paired hybrids had similar parent genetics. Carbon dioxide production by corn samples was used to calculate dry matter loss (DML), and time to 0.5% DML was used as the primary indicator of storability. Change in the fat acidity content of normal–oil and high–oil corn hybrids was determined and used as another possible indicator of relative storability. The mean adjusted times to 0.5% DML for normal–oil and high–oil corn hybrids were significantly different at a 0.05 probability level for all five hybrid pairs at 19% moisture, but time to 0.5% DML was significantly different for only two hybrid pairs at 22% moisture. The deterioration rate for high–oil corn was faster than for normal–oil corn in most hybrid pairs at both 19% and 22% moisture. Fat acidity values were significantly different at a 0.05 probability level for all hybrid pairs at both moisture levels, both before and after storability tests. Fat acidity values for high–oil corn hybrids were much higher than for comparable normal–oil content corn hybrids after the test. There was a strong positive correlation between oil content and fat acidity after storability tests at both moistures. In general, the high–oil corn hybrids had higher levels of damaged kernels (DKT) at the end of the storability tests, at both 19% and 22% moisture. Fat acidity and DKT results indicate that, at a given moisture content, some high–oil corn hybrids might not store as well as normal–oil content corn. For conventional and Bt corn hybrids, the mean adjusted times to 0.5% DML were significantly different at a 0.05 probability level for three hybrid pairs at 19% moisture and for four hybrid pairs at 22% moisture. In some cases, time to 0.5% DML was greater for the conventional hybrid, and in other cases, time to 0.5% DML was greater for the Bt hybrid. Differences in fungal counts and DKT values after storability tests were small for comparable hybrid pairs of conventional and Bt corn at both moisture levels. These results do not allow any conclusions to be drawn about the relative storability of Bt corn hybrids compared to conventional hybrids.