The results of the present study demonstrate that at lower doses (0.016 % and 0.031 %) significant changes in vegetative and yield parameters were obtained. Higher doses (0.125 % and 0.25 % NaN3) of the mutagen were deleterious. There was significant reduction in percentage germination compared to the control. No germination was however recorded in 0.125 % and 0.25 % NaN3 respectively. Shoot length increased in 0.016 % NaN3 treatment but decreased in the 0.031 % NaN3 treatment in cultivars TVU-3541 and TVU-3574 respectively, while TVU- 3615 and TVU-2521 showed decreases. Lower levels (0.016 % and 0.013 %) of NaN3 significantly increased leaf area in TVU-3615, TVU-2521, TVU-3541, and TVU-3485. No significant changes in chlorophyll content of leaves was recorded as a result of mutagenic treatments compared with control experiment. No significant changes in number of root nodules in the cowpea cultivars were recorded at 100 days after planting as a result of NaN3 treatments. However, sodium azide significantly enhanced the development nodules in TVU-3574. There were significant decreases in total dry weight of mutant plants compared to the control. No. of Pods/plant increased with increase in the concentration of NaN3 among all the cultivars.Since yield per plant is the most desirable character, at 0.031 % NaN3, TVU-3541 showed the highest number of pod/plant. Genetic parameters of some yield parameters of cowpea showed that observed changes resulting from NaN3 treatments are necessarily genetic rather environmental.
