Assessment of frequency, density and abundance of weed species in different Cropping Systems

This study was conducted at the Teaching and Research Farm, Obafemi Awolowo University, Ile-Ife, Nigeria to determine effect of cropping systems on weed diversity and weed seeds bank at various soil depths. Weed flora composition in different cropping systems were also correlated with land use history. Two broad cropping systems were considered namely; plantation cropping (cocoa, oil palm and cashew) and arable fields (maize, cassava/maize and a natural fallow which served as control. Twenty six weed families were recorded in all. Out of these 26 families, only two are grasses while the remaining were broadleaves. Oil palm and cashew plantations had the highest weed diversity. Using Shannon index (H>1.0), Panicum maximum (Poaceae) and Vigna gracilis (Papilionaceae) weeds were more frequently encountered across the cropping systems with diversity index H>0.5. Asteraceae, Papilionaceae, Rubiaceae were the broadleaves families widely distributed in the cropping systems. Results on the weed seed bank indicated that the number of weed seeds decreased as soil depth increased, the highest number of seeds was found in the soil layer of 0-8 cm. Keywords: Cropping System, Seed bank, abundance, densit