Influence of Eucalyptus camaldulensis Dehnh on the growth, productivity and physiology of three associated crops in the Sudano-Sahelian zone of Burkina Faso, West Africa

Abstract

Eucalyptus camaldulensis Dehnh is an exotic species found in Sahel agroecosystems, often growing alongside annual crops. However, there is limited documentation regarding its ecological impacts on these crops. This study aims to assess the influence of eucalyptus on crop physiological traits and yield. To accomplish this, on-farm experiments were conducted over two years (2022 and 2023), employing a tree effect gradient called a gradient-based design with 4–7 replications for cowpea, millet, and sorghum. The experimental design included three plot locations based on their proximity to the eucalyptus trunk: one directly under the crown, another centred at 11 m, and a control plot situated 22 m away. Various parameters, such as height, relative chlorophyll content, leaf area index, photosynthetically active radiation, and yields of grain straw, were measured across all plots and years. Results from pairwise tests indicated significant differences among the plots for most parameters studied. Notably, plant height significantly decreased in proximity to eucalyptus (p < 0.000) throughout the two years. For relative chlorophyll content, the millet and sorghum in 2022 presented significant differences between plots located at 22 m and plots under the crown (p = 0.000). The photosynthetically active radiation indicated significant differences between the plot located at 22 m and the plot under the crown in cowpea, sorghum (2022 and 2023). Additionally, grain and straw yields were significantly lower near the eucalyptus in both years (p < 0.05). These findings suggest potential ecological risks associated with growing certain crops close to eucalyptus in the Sahel context.