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Effect of Delayed Emergence on Corn Grain Yields

Lawles, Kyle Don
The purpose of this study was to determine corn grain yield reduction as a function of interplant competition arising from delayed emergence and to evaluate yield levels associated with 3 plant sequences, with and without delayed emergence. Delayed planting to simulate delayed emergence was used in this experiment to determine the adverse effects on final corn grain yield. When comparing 3 plant sequences, the results show that delayed emerging plants result in decreased corn grain yields. Over both sites and years, data showed that when the days of delayed planting was greater than 5 days there was almost always a significant yield reduction. When looking at the three plant sequences the delayed plant by 2,5, and 8 days continued to compete with the two non delayed plants. By 12 days these plants competed less with the two non delayed plants and that then tended to have higher by-plant yields. Results from this study will assist those groups interested in improving by-plant N fertilization by knowing how much a plant is delayed and how that ultimately affects final corn grain yields. This information will in turn be used to estimate N removal based on yield level (or projected yield decrease) based on how much each plant is or is not delayed versus neighboring plants. When evaluating both sites and years, for each day delay emergence (estimated using delayed planting), grain yield depression ranged from 225 kg ha-1 to 1379 kg ha-1.