Allelopathic effect of leaf and seed extract of nutgrass ( Cyperus tuberosus ) on the germination of beans ( Vigna unguiculata (L.) Walp)

The effect of leaf and seed extract of nutgrass (Cyperus tuberosus) on the germination of cowpea (Vigna unguiculata (L.) Walp) was investigated at the microbiology laboratory of the Science Laboratory Technology Department, Federal Polytechnic Mubi, using six aqueous extracts: control (0.0 g cm−3), 0.5, 1.0 1.5, 2.0, and 3.0 g cm−3. The experiment was laid out in a completely randomized design replicated three times. Results revealed that the aqueous leaf extract had more toxic effect on the germination of cowpea seed especially at the 3rd day to 9th day of germination. The concentration 1.0 g cm−3 gave a significant (p ≤ 0.05) effect in the last 5 days of the germination experiment and is a better germination, while the higher concentration 3.0 g cm−3 had recorded barely no germination at all from day 1 to day 13 of the experimental period. Bioassays also indicate that the inhibitory effect was proportional to the concentrations of the extracts that is the higher the concentration the stronger inhibitory effect, whereas the lower the concentration the lower stimulatory effect in some cases. This investigation therefore comparatively reveals that the leaves extract of C. tuberosus has more allelopathy than seed extract.