Cowpea provides a cheapest source of protein with an average range of protein content of 23-30%. However, cowpea growth, development, and yield are greatly affected by drought during flowering and pod filling in the sub Sahelian areas. The best way to cope with this situation is to develop drought tolerant cowpea varieties. The objective of this study was therefore to evaluate cowpea lines developed through mutagenesis using gamma radiation to assess their reaction under optimal and water stressed conditions. The response of ten mutants irradiated Moussa local was then evaluated in pots arranged in a split plot design in a screen house. Two conditions were applied with optimum and water-stressed conditions. The stress was applied for two weeks at flowering. Two cowpea varieties Gorom local (drought tolerant) and Moussa local (susceptible) non-irradiated were used as checks. Thereafter, field trials under two different sowing dates were conducted to identify the best tolerant mutant line(s) using agro-morphological and tolerance indicators. The results indicated that two mutant lines (MoussaM51-4P10, MoussaM43-20P14) exhibited better stress tolerance and produced higher yield under water stress conditions. Stress tolerant index (STI) was better to select cowpea mutant tolerant with higher yielding under moderate stress (SI=35%). The study confirmed that Gamma radiation induced best mutant line in cowpea (MoussaM51-4 P10 and MoussaM43-20P14) with best yield performing under water deficit condition.

cowpea, gamma rays, water stress, tolerance