Effect of Shade on Velvetleaf (Abutilon theophrasti) Growth, Seed Production, and Dormancy

Growth, seed production, and dormancy of velvetleaf in response to shading were evaluated in the field. Velvetleaf plant height, leaf number, number of branches, and plant dry weight decreased linearly with increasing shade. No differences were observed for plant height, number of leaves, or branches/plant when plants were shaded 30% or not shaded throughout the growing season. However, the 76% shade treatment reduced velvetleaf height (1984 only), leaf number, stem branches, and plant dry weight. These reductions were greater in 1984 than 1985 except for plant dry weight that decreased by 88% each year. The number of capsules and the number of seeds/plant decreased linearly with increasing shade levels, while the seed weight increased with increasing shade level. Shading also decreased seed dormancy. These results demonstrate that shade suppresses velvetleaf growth and seed production, and shortens the dormancy of seeds that are produced by these plants.