ORIGINAL ABSTRACT

Biological invasion changes the ecological and physiological functions of invaded ecosystems. Various control methods, including tillage, digging, burning, and chemical treatments, have been tested to manage invasive plant species. The commonly used broad-spectrum herbicide glyphosate is often applied for unwanted plant control. However, it has a significant residual impact on underground water, sediments, and drinking water, reaching levels of up to 70 μg/L. This poses risks to aquatic species, microflora, and human health. In this study, a natural herbicide derived from Sorghum bicolor root extract was foliar sprayed at different concentrations (0, 20, 40, 60, 80, and 100 %) along with low and high concentrations of glyphosate to control the growth of Solidago canadensis. The natural herbicide demonstrated significant potential to change the morphology, physiology, and biochemistry of S. canadensis under high concentrations, reducing the reliance on glyphosate by up to 60 %. It led to a decrease in root biomass ranging from 26 % to 81 %, leaf area reduction of 11 %-60 %, and a decrease in photosystem II efficiency. Catalase and ascorbate peroxidase activities were also significantly affected, showing a decrease of 49 %-77 %, and stomatal pore size was reduced from 58 % to 91 %. This may impede the gaseous exchange between the plant and its surroundings. The use of the natural herbicide, in combination with low concentrations of glyphosate, holds the potential to manage S. canadensis, control biological invasion, and mitigate the residual effects of glyphosate by inhibiting the shikimate pathway.