Physiological and Anatomical Responses of Water Hyacinth, Eichhornia crassipes and Water Lettuce Pistia stratiotes to Allelopathic Effect of Some Plant Extracts as potential agents for the control of aquatic weeds

Abstract

A three-season study conducted during the 2021–2024 period at the Weed Research Central Laboratory, Giza Research Station, ARC, Egypt, evaluated plant-based allelochemicals for controlling water hyacinth, Eichhornia crassipes and water lettuce, Pistia stratiotes. The experiment followed a randomized complete block design (RCBD) with four replicates. Treatments included aqueous sweet basil extract, basil and camphor oils with a Tween adjuvant, and acetic acid, applied twice at one-week intervals. Results obtained showed a significant reduction in chlorophyll a, chlorophyll b, and carotenoid content, with water lettuce being more affected than water hyacinth. Pigment contents decreased progressively over time, reaching a peak at 21 days post-treatment, leading to over 96% mortality of water hyacinth and 100% mortality of water lettuce. Camphor and basil oils had the highest impact, followed by acetic acid, while aqueous sweet basil extract was the least effective. Anatomical changes in water hyacinth roots and petioles were minimal. These findings suggest that these natural compounds can serve as effective, eco-friendly alternatives for controlling invasive aquatic weeds.

Keywords:

Allelochemicals, water hyacinth, water lettuce, camphor oil, basil oil, aqueous sweet basil extract, acetic acid, pigment content