Abstract
In sub-Saharan Africa, the invasive plant Parthenium hysterophorus (Parthenium) is threatening ecosystem integrity, biodiversity, and smallholder livelihoods. But, there is no single effective method of controlling it. Desmodium intortum, Lablab purpureus, and Medicago sativa were tested for their capacity to suppress Parthenium, as well as the allelopathic potential of Desmodium uncinatum leaf crude (DuLc) extract. While the study investigated the effect of DuLc extract concentrations on seed germination and seedling growth in laboratory, pot, field plot, it also assessed the effect of selected suppressive plants on Parthenium growth. It was found that high levels of DuLc concentrations and suppressive plants inhibited Parthenium germination and growth. When Parthenium was grown with suppressive plants, its growth was inhibited compared to when it was grown alone. When grown with all three test plants, the stem height and total fresh biomass of Parthenium seedlings were lowered by more than 60% and 59% in pots, and 40% and 45% in plots, respectively. Parthenium seed germination was decreased by 57% in plots, 60% in pots, and 73% in petri dishes at higher DuLc concentrations (i.e. 75% and 100%). Parthenium seedling stem heights were 36% (in plots) and 30% (in pots) shorter when sprayed with higher concentrations of DuLc. Overall, the findings of this study suggest that suppressive plants and those containing allelochemicals can be employed as a management tool to combat Parthenium invasion in sub-Saharan Africa, notably in Tanzania.