Corn, Sunflower, and Soybean Emergence Influenced by Soil Temperature and Soil Water Content

The influence of soil temperature and initial soil water content on subsequent germination and emergence of corn ( Zea mays L.), sunflower ( Helianthus annuus L.), and soybean [ Glycine max (L.) Merr.] needs to be understood. Previous research has not determined whether emergence of corn and sunflower is reduced by soil water content that is high enough for seed imbibition but too low for radicle emergence from the testa. Our objective was to evaluate corn, sunflower, and soybean emergence influenced by initial seed‐zone soil water content of 0.05, 0.07, and 0.09 kg kg −1 and soil drying at three day/night (17/8, 21/12, 25/16°C) soil temperature regimes as the number of days of soil water deficit and temperature stress increased. A factorial experiment with two replicates was conducted under controlled temperature conditions in an incubator. This experiment was conducted using a Glyndon silty clay loam (coarse‐silty, frigid Aeric Calciaquolls). Corn emergence was >85% at all three initial soil water contents and temperature regimes. Sunflower emergence increased from 59% at the low initial soil water content to 90% at the higher initial soil water content. Soybean emergence was 22% after stress was imposed by a 0.07 kg kg −1 initial soil water content (high enough for seed imbibition but too low for germination). If soil water content is sufficient to imbibe seeds of soybean and sunflower, but too low for germination during the 6 d after planting, producers may need to replant, especially when soil temperature is above 21/12°C.