Allelopathic Activity of Itchgrass (Rottboellia cochinchinensis) and Its Phytotoxicity in Soil

Abstract

Farmers in Chaehom-Lampang area use itchgrass [Rottboellia cochinchinensis (Lour.) W.D. Clayton] as a mulching material to control the other weeds. The phytotoxicity of soil incorporated with itchgrass powder was investigated under an environment duplicating field conditions. The results showed that soil incorporating itchgrass powder had phytotoxic effects on the growth of Bidens pilosa, Echinochloa crus-galli and Lactuca sativa, the effect was intensified with increased concentrations of itchgrass powder. Allelopathic activity of itchgrass in soil exhibited a maximum effect at 0-15 days after incorporation and then decreased over time. Additionally, the allelopathic activity of itchgrass was lower in submerged condition than half-saturated conditions and in dry conditions allelopathic activity was the highest. These results suggested that the allelopathic activity is also influenced by timing and soil moisture condition. A better understanding of the allelopathic activity of itchgrass in soil will provide information crucial in enabling improvements in the basis of weed management.