Influence of Cultivar and Seed Characteristics on Vertical Weight Displacement by Soybean Seedlings

Abstract

Emergence of soybean [Glycine max (L.) Merr.] seedlings often is erratic, especially when soil crusts form after heavy rains. Information is limited on traits that may affect the ability of soybean seedlings to emerge through compacted soils. The objectives of this study were to determine the effect of cultivars, position of pods on the plant, position of seeds in the pod, and number of seeds per pod on displacement of a 65‐g weight by soybean seedlings at 25°C. Vertical displacement of a 65‐g weight by individual seedlings in a controlled environment chamber was used to measure hypocotyl exertion force of individual seedlings. Seed size, weight, and density also were measured to determine the association of these seed traits with seedling weight displacement. Fifteen soybean cultivars of Group V maturity were grown under irrigated conditions on a Captina silt loam (fine‐silty, mixed, mesic Typic Fragiudult) at the Main Experiment Station, Fayetteville, AR. Seeds from these cultivars produced seedlings that had significantly different weight displacement values. Seeds produced on the upper one‐third of the plant produced seedlings that exhibited forces greater than those from the lower two‐thirds of the plants. Seedlings from seeds in two‐seeded pods had significantly higher weight displacement values than those from one‐seeded pods, and seeds from three‐seeded pods were intermediate in weight displacement. Cultivars differed significantly in mean seed size, weight, and density, but these seed parameters were not highly correlated with seedling weight displacement values. Coefficients of determination (r2) for the association between physical characteristics of seed and weight displacement by seedlings generally were <1.0%. Results indicate that genetic differences exist for seedling emergence potential in soybean, and that it may be possible to use this parameter to improve seedling emergence under compacted soil conditions.