Row spacing, plant density, and hybrid effects on corn grain yield and moisture

Producing corn (Zea mays L.) in narrow row spacings has been attempted over the last several decades with varying degrees of success. The objectives of this study, are to determine: (i) if there is a different optimum plant density or (il) if hybrids of varying relative maturity respond differently for corn grown in narrow row spacings (38 cm) compared with conventional row widths (76 cm). These studies were conducted at six locations across Iowa over 3 yr. Averaged across years, locations, and plant densities, corn grown in 76-cm row spacings produced higher yields than that grown in 38-cm rows (10.5 vs. 10.3 Mg ha(-1), respectively). Harvest moisture content of corn grown in 38-cm row spacings was significantly less than that of corn grown in 76-cm row spacings (160 vs. 161 g kg(-1), respectively). Averaged across years and locations, there was no statistically significant (P < 0.05) yield difference between the two row spacings for four of the six hybrids tested. Hybrid MAX23 yielded significantly more grain in 76-cm row spacings (9.4 vs. 8.9 Mg ha(-1)) while 'MAX454' yielded more grain in 38-cm row spacings (10.0 vs. 9.8 Mg ha(-1)). It is thus concluded that optimum plant densities for narrow-row corn production are similar to those required to produce maximum yields for conventional wide-row corn production. In addition, a strong hybrid x row spacing interaction among the six hybrids tested here suggests that certain hybrids may perform better at prescribed row spacings.