Potential Suppression Effects of Aqueous Extracts of Selected Plants on Growth of Carrot Weed (Parthenium hysterophorus L.) in Arusha, Tanzania

Abstract

This study investigates the potential suppression effects of aqueous extracts derived from selected plants on the growth of carrot weed (Parthenium hysterophorus L.) in Arusha, Tanzania. The research aimed to explore natural and sustainable methods for managing the proliferation of this invasive weed species. Through a series of laboratory experiments, aqueous extracts were prepared from specific plants namely amaranth (Amaranthus spinous L.), neem (Azadiratchta indica L.) wheat millet (Sorghum bicolor), and marigold flower (Tagetes erictus L.). The extracts were tested against carrot weed in the laboratory and pot experiment for their effectiveness in inhibiting the germination and growth of carrot weed seeds under controlled conditions. Leaf extracts at 25, 50, and 100% concentrations were sprayed on four and eight-week seedlings of P. hysterophorus. Distilled water was used as a control. The highest germination percentages were 95.5% and 93.33% in the control treatment for T. erictus flower extract and the leaf extracts respectively. Results showed that all plant extracts tested indicated high inhibition of growth and germination rate of P. hysterophorus. Due to increasing concentrations, from 25 to 100%. However, 100% concentration was more effective in all plant extracts used. Four weeks seedlings were more susceptible to foliar sprays compared with eight weeks seedlings. These findings highlight the potential of using locally available plants to develop eco-friendly strategies for managing carrot weed infestations in the region. Further research is warranted to identify and isolate the active compounds responsible for the observed suppression effects. This study contributes to the knowledge of sustainable weed management practices and underscores the importance of exploring nature-based solutions for agricultural challenges in Tanzania and beyond.