COS 72-4
Effects of density and sowing pattern on weed suppression and grain yield in three varieties of maize under high weed pressure
We tested the hypothesis that improved weed suppression by maize can be achieved through increased crop density and spatial uniformity. Field experiments on three varieties of maize sown at three densities (5, 7 and 10.5 seeds m-2) and in two spatial patterns (grid pattern and rows) under very high weed pressure from a local weed, Brachiaria brizantha, were performed in Colombia in 2012 and 2013. We measured weed biomass one month after sowing and at harvest, and grain yield at harvest.
Results/Conclusions
Density, variety and sowing pattern all had strong and significant effects on both weed biomass and yield. On average, weed biomass was reduced (by 71.48% in the first year and 58.15% in the second year) and grain yield was increased (by 48.10% and 43.54%) at the highest density in the grid pattern in comparison with standard sowing practices (medium density in the row pattern), and there was a significant density x variety interaction, showing that there are genetic differences in the response of the varieties to density. The variety that suppressed weeds best at high density had the lowest variation in the angle of insertion of the first leaf, consistent with the hypothesis that reduced phenotypic plasticity may be advantageous for weed suppression under high density and spatial uniformity. We conclude that increased density and uniformity can contribute to weed management in maize in many cases, reducing the need for herbicides or mechanical weed control.