Jason Satterwhite1, Kipling Balkcom2, Andrew J. Price2, Francisco Arriaga2, and Edzard Van Santen3. (1) Auburn Univ, Funchess Hall, Auburn, AL 36849, United States of America, (2) USDA-ARS, 411 S Donahue, Auburn, AL 36832, (3) Auburn Univ, Agronomy Dept, Auburn, AL 36849-5412
Corn (Zea mays L.) seeded in narrow row patterns can increase yields and accelerate canopy closure; however, costly equipment modifications make narrow rows impractical. Twin row patterns are a compromise to enhance the benefit of narrow rows with fewer equipment modifications. We compared yield, water content, and leaf area index (LAI) for a conventional and a glyphosate-tolerant hybrid across three plant populations (low 39000-44000; medium 64000-69000; high 79000-84000 plants ha-1) in two row patterns (single vs. twin) at four locations during the 2005 growing season. The experimental design was a RCB (r = 4) with a split-split plot restriction on randomization, where corn hybrids were assigned to main plots, row patterns to subplots and plant populations to sub-sub plots. A significant hybrid×population interaction was observed at three out of four locations. Grain yield for the conventional hybrid was 15% (8670 vs. 7370 kg ha-1), 12% (9940 vs. 8770 kg ha-1), and 16% (8680 vs. 7330 kg ha-1) higher than the glyphosate-tolerant hybrid at the medium population. However, yields did not always increase at high populations. Row pattern had inconclusive effects on grain yields and water content. There was minimal evidence to support more efficient use of water with increased populations and twin row patterns. At two locations, LAI values of the twin row pattern were 13% (3.1 vs. 2.7 m2 m-2) and 10% (3.3 vs. 3.0 m2 m-2) higher than the standard row pattern. Seeding corn in rotation with crops already utilizing twin row systems can maintain corn yields without increasing conversion costs; however, converting corn production to twin rows may not always increase corn grain yields.