Soil Moisture, Temperature, and Drying Influence on Soybean Emergence

Abstract

AbstractSoybean [Glycine max (L.) Merr.] emergence is influenced by the interaction of initial seed zone soil water content and temperature. Stress due to soil water content that is great enough for seed imbibition but too low for radicle emergence from the testa reduces emergence. Previous research has not determined whether emergence is reduced by soil drying after the seeds have imbibed water. Our objective was to evaluate soybean emergence influenced by initial seed zone soil water content and soil drying at three day/night soil temperature regimes (17/8, 21/12, and 25/16°C) as the number of days of soil water deficit and temperature stress increased. The experiment was conducted under controlled temperature conditions using an incubator. Emergence depended on both initial seed zone soil water content and temperature. As the number of days of soil moisture deficit increased, soil drying reduced emergence at initial soil water contents of 0.07 and 0.09 kg kg−1. If the radicle had emerged from the testa and the soil water content was reduced below the initial soil water content due to drying, emergence was reduced. If seed imbibition occurred, but the initial soil moisture was too dry for the radicle to emerge from the testa, emergence decreased as the number of days of stress increased. The results show that the influence of seedbed drying on percent emergence depended on the initial soil water content and the number of days until adequate soil water content was restored.