Soybean Seedling Emergence Influenced by Days of Soil Water Stress and Soil Temperature

Abstract

Abstract Soybean [ Glycine max (L.) Merr.] producers often plant into a dry seed bed rather than waiting until soil water conditions are optimum for germination and emergence. In some cases, there is sufficient water for imbibition, but not enough for germination. Producers need to know how long seeds can remain viable under this type of stress. Our objective was to evaluate, under controlled conditions, the influence of soil temperature, soil water content, and duration of stress on soybean emergence and seedling development. Our experiment consisted of a factorial combination of (i) three temperatures regimes (low, 17/8°C day/night; medium, 21/12°C, and high, 25/16°C), (ii) four gravimetric soil water contents (0.07, 0.09, 0.11, and 0.13 kg kg −1 ), and (iii) three stress durations (0, 6, and 12 d). Soil water content influenced seedling development and emergence, and there was a significant temperature ✕ soil water interaction for both traits. Length of stress also influenced seedling development and emergence. In general, emergence was poor after 12 or more days of soil water conditions that allowed seeds to imbibe water, but were too dry to allow the radicle to emerge from the testa. Under these conditions, seedling emergence decreased as soil temperature increased. Producers can use this information regarding the length of stress interval at a given seed stage as indication of when replanting would be necessary.