Influence of Cultural Practice and Field Environment on Consistency of Corn Yields in Northern Areas1

Abstract

AbstractFour adapted corn hybrids (Zea mays L.) were grown in 76 cm and conventional rows at populations per hectare of 40, 50, 60, and 70,000 in 12 environments as provided by planting date and irrigation over a four−year period at two locations in Wisconsin. Analyses of variance were computed for yield within environments and at each hybrid‐cultural combination across environments. Attention was given to determining and interpreting optimum hybrid−cultural combinations within environments and consistency of performance across environments.Average overall grain yield was 6,394 kg/ha; and maximum yield was 11,441 kg/ha. Yield in conventional rows averaged 93.6% of yield in 76−cm rows, with greater differences for the dry year, late plantings, high populations, and late hybrid. In the favorable environments, first planted and irrigated, yields increased with population up to 60,000 while in the unfavorable environments, late planted and non−irrigated, yields were highest at the low population. Differences due to population were more pronounced in the unfavorable environments. Variance across environments averaged lowest for the 40,000 population and highest for the 70,000 population and for the late hybrid. Hybrid differences were greater for the first planting and in non−irrigated plots. Hybrid and population effects were small under irrigation. Coefficients of variability averaged highest for the unfavorable and lowest for the favorable environments.