Allelopathic Plants: 33. Rottboellia cochinchinensis (Lour.) W.D. Clayton

Abstract

Itchgrass [Rottboellia cochinchinensis (Lour.) W.D. Clayton] is a C4 annual upland grass, which is self-pollinated and invades disturbed and agricultural areas in more than 40 countries in tropical and subtropical regions of the world. The plant exerts high competition for row crops due to its high tillering capacity. Conversely, itchgrass is an allelopathic plant, which is often used as a mulching material for weed control in vegetable fields in Chae Hom district, Lampang Province, Northern Thailand. Itchgrass plant mulch can conserve soil moisture, minimize soil erosion and suppress other weed species. In this review, the available published literature has been compiled to understand the mechanism of allelopathic action of this important grass and to highlight its significance in the cropping systems. It has been noted from the literature that the allelochemicals released from itchgrass in the soil can adversely influence the germination of some adjacent weeds and test crops, causing a growth reduction of seedlings. Various authors have concluded that trans-p-coumaric acid (trans-4-hydroxycinnamic acid) is the major allelochemical present in itchgrass. Additionally, two active substances have been reported to be isolated from n-hexane crude extracts of the itchgrass aerial part and has been identified as linoleic acid (9,12-octadecadienoic acid) and linolenic acid (9,12,15-octadecatrienoic acid). It can be concluded that both direct and indirect allelopathic effects are involved in facilitating succession of itchgrass plant. Better understanding of its allelopathic potential will provide a basis for improving the non-chemical weed management strategies in vegetable fields for sustainable agriculture.