Toxic effects of leachate of water hyacinth decay on the growth of Scenedesmus obliquus (chlorophyta)

Effects of leachate of leaf and root litters of water hyacinth, collected after various periods of decay, on the growth of a green alga Scenedesmus obliquus (Turpin) Kuetzing were determined. Leachates of the leaf and root litters showed very similar effects on the growth of test alga. Higher concentrations of the leachate of 1-day decay considerably stimulated algal growth. Lower concentrations of the leachates of 10-, 35- and 60-day decay caused growth toxic effects in comparison with higher concentrations. The inhibition of algal growth was significantly higher by the leachate of 60-day decay relative to that by the leachates of 35- and 10-day decay. Short-term incubation of the test alga with the leachate recorded a greater inhibition of growth than long-term incubation.