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Threats on native flora and fauna by invasive plant species represent one of the main conservation and management
challenges in rangelands. Methods that are both effective and ecologically safe to suppress invasives are
urgently needed but have rarely been used, thus, highlighting the need to devise and test ones. In our study,
we used a completely randomized design to assess the allelopathic effects of Desmodium uncinatum and
Desmodium intortum leaf (DuL, DiL respectively) and root (DuR, DiR respectively) extracts on germination and
seedling vigor of the invasive weed Tagetes minuta.We also assessed seedling germination, height, fresh weight
and chlorophyll content after fourteen days and thirty days of treatment separately. The mean percentage germination
per treatment in and across each group differed significantly (P b 0.05), with DuL having the highest suppressive
effect (P = 0.003). Likewise, the mean germination per treatment was more strongly negatively
correlated with treatment concentration in DuL treatments in both laboratory and screen house experiments
(r = −0.48, P = 0.0003 and r = −0.91, P b 0.0001 respectively) than in DuR, DiL and DiR. Seedling height,
fresh weight and chlorophyll content (Chl) differed significantly (P b 0.05) between the four treatment groups.
Seedlings treated with higher concentrations were observed to be shorter, having lower fresh weights and Chl
content than those treated with lower concentrations. The DuL higher concentration showed a trend of shorter
seedlings with lower fresh weights and Chl content than other groups. Our findings suggest that D. uncinatum
may probably be used to control invasive species, T. minuta and should be integrated into the management practices
in the affected areas. Also our data suggest that a potential exists in devising an innovation that is both ecologically
safe and effective by using Desmodium spp. making it possible to improve rangelands production
through planting them in the areas affected by invasive species. |
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