A nursery experiment was conducted to investigate the allelopathic effects of Eucalyptus camaldulensis on growth variables (seedling height, girth and number of leaves) of Arachis hypogea (groundnut). Aqueous leaf extracts of Eucalyptus camaldulensis (cold and hot water solutions) were used at different rates (0%, 25%, 50% and 100%) as treatment to determine their effects on groundnut. Eucalyptus camaldulensis leaf powder was extracted using hot and cold water methods at different concentrations (0g, 25g, 50g, 100g per liter). Hot extraction involved heating for 20 minutes, while cold extraction involved soaking for 2 days. The study employed a 2 x4 Randomized Complete Block Design (RCBD) with 70 polythene bags and 10 replicates per treatment level. The results showed significant inhibition of seedling growth, with the hot treatment (T2, 25 %) exhibiting the highest inhibitory effect in the seedling height (12.120 %), and (T2, 25 %) in the hot treatment showing the highest inhibitory effect in the seedling girth (1.070 %), also hot treatments (T2, 25 % and T4, 100 %) showed the highest inhibitory effect with 36.800 number of leaves in both. The hot Eucalyptus camaldulensis aqueous extract had a greater inhibitory effect on the growth rate compared to the cold aqueous extract, the results showed significant variation (P<0.05%). The study concluded that Eucalyptus camaldulensis allelopathy can negatively impact groundnut production. Overall, Arachis hypogaea should not be planted in association with Eucalyptus camaldulensis trees due to its inhibitory effects (allelopathy) on the plant growth.
Kafinga et al. (Wed,) studied this question.