Maize Management Effects on Plant-to-Plant Variability and Grain Yield
Conditions within maize (Zea mays L.) fields can cause plant-to-plant variability (PPV) because of emergence, spacing, and mid-season growth non-uniformities. PPV has been associated with yield reductions in maize. Maize growers can influence field conditions and maize yields through management practices such as rotation and tillage. The objectives of this research were to determine the effect that tillage and crop rotation systems have on maize growth and PPV, and whether PPV is a mechanism for yield differences observed among management systems. Field experiments were conducted at the Elora Research Station in Ontario, Canada in 2010 and 2011, where maize was grown under various tillage and rotation treatments. Plant-level measurements were taken throughout the season. Diverse crop rotations and conventional tillage (CT) increased grain yields. Maize grown in no-tillage (NT) treatments had later seedling emergence, lower leaf numbers throughout the season, shorter plants at silking, later anthesis and silking, and lower plant grain yields compared to CT treatments. Rotations that incorporated alfalfa or cover crops had earlier silking dates and fewer plants that were developmentally delayed compared to mono-crop rotations. PPV was characterized using variance (s2) and the coefficient of variation (CV), but the two approaches did not drastically change the outcome of the study. Tillage more consistently altered PPV than rotation treatments. NT had higher variability in emergence, leaf number, silking date, plant spacing, anthesis-silking interval, and harvest index than CT. Higher variability in emergence, early-season leaf number, dry matter at silking,and harvest index were found to be mechanisms for lower yields in NT treatments. This research suggests that producers should take measures to limit variability in these parameters due to their associations with yield reductions, especially when growing maize in NT systems.