Abstract

Allelopathy in plants can be instrumental in the suppression of weeds in a crop-weed interaction. Soybean has been found to exhibit allelopathetic effects by inhibiting speargrass germination and subsequent growth. The results showed that soybean and velvet bean extracts significantly reduced speargrass germination by 46 and 54% respectively. There was significant reduction in shoot and root length of speargrass by 37 and 63% respectively compared with the control. Bioassay test on maize (TZL COMP. 4 CL) showed positive response to extracts application. However maize treated with velvetbean (Mucuna cochinchinensis) extract had significantly lower root length. Speargrass seeds treated with the extracts of TGX 1910-8F, TGX1448-2E and TGX 1864-17F had significantly lower seed germination and seedling growth. The presence of allelochemical(s) is implicated in the study.

Key words: Allelochemical(s), speargrass, soybean genotypes, extracts.