No‐Till Effects on Yield and Plant Density of Maize Hybrids 1

The use of no‐till practices for the culture of maize ( Zea mays L.) is increasing because it reduces time, fuel, and labor requirements for land preparation. Studies have indicated that minimum tillage practices can slow maize growth and reduce plant stand density and grain yield. Little information is available on hybrid adaptation to these tillage systems. Field experiments were conducted to determine how grain yield and plant density (plants/ha) were affected by conventional (plowing followed by discing) vs. no‐till practices in commercial maize hybrids. Four locations in Maryland were used, including sites on the coastal plain (Typic Hapludult and Aquic Hapludult) and piedmont (Typic Hapludalf). The split‐plot experiment had tillage (conventional vs. no‐till) as the main plots and commercial maize hybrids, varying in cold tolerance and maturity, as the subplots. Six hybrids were grown in 1982 and 12 hybrids were grown in 1983 and 1984. The hybrid × tillage method interaction was not significant for plant density and was inconsequential for grain yield except at the Beltsville location. No one hybrid performed consistently better under conventional tillage. In 1982 tillage did not significantly affect grain yield; however, in 1983 grain yields for the no‐till practice were 17 to 24% greater than yields for conventional tillage at three of the four locations. In 1984 one location showed a 19% increase in yield under no‐till. Changes in plants/ha due to tillage ranged from a 22% decrease to a 4% increase under no‐till. The analysis of covariance between grain yield and plants per hectare indicated that there was no significant correlation between these parameters. These results indicated that selection for genetic traits to improve grain yield under no‐till practices may not be necessary for this geographical area. These commercial maize hybrids would produce similar amounts of grain under either tillage practice.