COLCHICINE-INDUCED VARIATIONS IN COWPEA (VIGNA UNGUICULATA L. WALP)

Cowpea is very important in the tropical and sub-tropical regions of Africa where it serves as a
source of protein for the local population coupled with its ability to fix atmospheric nitrogen. Induced mutation has
been successful in many crop species but least applied in legumes like cowpea. Experiment was conducted on
colchicine induced variations in cowpea by exposing the apical shoots of seedlings of two cowpea accessions
(NG07 and NG08) to 0.2% colchicine in semi-solid agar. Semi-solid agar proved to be an effective medium of
applying colchicine to apical shoots of cowpea seedlings. Traits like plant height, number of pods per plant and
seeds per pod were reduced by colchicine treatment compared to control. Terminal leaflet length and number of
nodes were enhanced by colchicine treatment compared to control and seed weight was significantly enhanced in
both accessions compared to the control. There were contradictory responses to colchicine treatment between the
two accessions for peduncle length, number of primary branches and pod length, indicating response to be genotype
specific within a species. Colchicine caused noticeable differences in qualitative traits like twining tendency, plant
pigmentation, testa texture and leaf colour for both accessions. The range of variations observed from this study
indicates a better possibility of genetic breeding through this approach.