Planting Date and Growing Season Effects and Interactions on Growth and Yield of Maize

Abstract Two maize (Zea mays L.) hybrids were planted on three dates from April 20 to May 24 each over an 8‐year period in Northern Virginia. All plots were harvested each year when the later hybrid in the latest planting had reached maturity. Data were obtained on yield of grain, days to silk, moisture in the grain at harvest, plant and ear height, and lodging. Significant planting date ✕ year interactions were found for yield, plant height, shank length, root lodging, and stalk lodging. The dominant factor affecting these traits was the rainfall amount and distribution as it related to the silking dates in the different plantings. There was very little difference in average yield between dates of planting, but the planting date ✕ year interaction was highly significant. Both the latest and the earliest planting dates were superior to the other two in different years. Plant height and shank length increased at successive planting dates in years of favorable rainfall, but both decreased at successive planting dates in years of severe late June‐July droughts. Ear height increased at each successive date of planting. Significant differences in root and stalk lodging occurred only in one year when, during a severe August storm, the early planting stalk lodged and the late planting root lodged most severely. Silking was delayed approximately ½ day for each day's delay in planting.