Effect of Glycine max canopy characteristics, G-max interference, and weed-free period on Solanum ptycanthum growth

Additive and replacement series studies were conducted ro investigate the e ffect of Glycine max cultivar canopy characteristics, interference, and wee d-free period on the vegetative and reproductive growth of Solanum prycanth um. Solanum ptycanthum established 0, 2, and 4 wk after planting (WAP) did not reduce seed yield of either Group II (Pioneer 9273) or Group IV (Asgrow 4715) varieties. The Group IV variety intercepted a greater percentage of light throughout the season. However, both varieties reduced growth of S. p tycanthum established 2 and 4 WAP, suggesting no disadvantage of Group II i n suppressing S ptycanthum growth. The greenhouse and field replacement ser ies experiments indicated that S. prycanthum plants experienced greater int raspecific than interspecific competition; that is, S. ptycanthum grew more in mixed species competition than in monoculture. Under field conditions, G. max grew equally well in competition with S, ptycanthum or in monocultur e. However, in the greenhouse G. max accumulated more biomass and fruit wei ght in monoculture vs. competition with S. ptycanthum. Relative yield total values (RYT) in the field supported greater productivity per unit area for mixed species competition when compared to G. max or S, ptycanthum grown i n monoculture. Data from both studies suggested that S. ptycanthum did not reduce G. max yield when grown in the field. Regardless of maturity group, a fully developed G. max canopy reduced S. ptycanthum growth.