Growth Analysis of Soybeans (Glycine max) in Competition with Jimsonweed (Datura stramonium)

Abstract

Field experiments were conducted to study the effects of jimsonweed (Datura stramoniumL.) densities and planting dates on the growth and yield of soybeans [Glycine max(L.) Merr. ‘Amsoy 71’]. Jimsonweed densities of 1.5 and 2 plants/m2did not reduce the dry weight of soybean leaf, stem, root, or pod and seed tissues, leaf area index, plant height, pod number, or seed yield when soybeans and jimsonweed were planted at the same time. Weed densities ranging from 3 to 16 plants/m2did reduce one or more of these soybean growth parameters. A significant density-by-year interaction was observed in which soybean growth reductions caused by high jimsonweed densities were less when competition for water was minimized by above-average precipitation in 1 of the 2 yr. No density of jimsonweed that emerged when soybeans were at the fourth trifoliolate-leaf stage reduced crop growth or yield.