Bt GENETICS EFFECT ON CORN HYBRID PERFORMANCE: A COMPARISON OF TWO NEAR ISOLINE CORN HYBRIDS
Kratochvil, Robert J
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Most corn (Zea mays L.) hybrids planted in the U.S. are the result of genetic modification that gives them a Bt gene or genes obtained from the bacterium, Bacillus thuringiensis (Berliner) (Bt), that express insecticidal proteins and enables these hybrids to be resistant to several insects. European corn borer (ECB) (Ostrinia nubilalis, Hübner) is the main Lepidopteran pest targeted by the Bt corn technology. All Bt events used in current corn hybrids provide 100% control of ECB. This has led to widespread use of Bt hybrids and has resulted in a drastic decrease in the ECB population. This raises the question whether it is still economically feasible to plant Bt hybrids that have higher seed costs in environments where the ECB pest level is low. The objectives of this study were: 1) compare the yield and agronomic performance of a pair of corn near-isoline hybrids with and without the ¬Bt traits; and 2) evaluate the agronomic and economic optimums for yield and nitrogen (N) rate for each near-isoline hybrids. A two-year study at three University of Maryland research farms in 2013-2014 examined each hybrid type for stalk damage due to ECB, yield performance, the optimum N rate for maximizing yield, and the economic returns the two hybrids provided. This study found minimal ECB stalk damage and no consistent agronomic or economic yield difference between the Bt and non-Bt hybrids. Neither hybrid type was determined to have a consistent nitrogen use efficiency (NUE) advantage. The results of this study indicate that producers should not have concerns over hybrid type choice, now that there is significant regional suppression of ECB below economic levels.