Using water regime and biophysical applications on expansion agricultural area are very obligatory to achieve self sufficiency of crops. Pretreated cowpea seeds by four - doses (G) 0, 15, 25 and 35 Krad., were grown till maturity to determined their response under three water deficit percentage (W) 100, 85, 70%. (G) in conjunction with (W) results, were evaluated in terms of seed and yield indexes "SI","YI", biological and economical yields "BY" and"EY", harvest index "HI", water use efficiency “WUE”, irrigation water productivity “IWP” and seed crude protein "CP", using split plot design. Results affirmed that all parameters had direct relations with studied treatments. Whereas, (W) has constrictive and significantly effects on all parameters except, EY and CP. So, irrigation regimes might not be increased more than 15%. In contrast, - irradiation – till 15 krad- has stimulatory and significantly (P 0.05) effects on SI, YI, EY, HI, WUE, and IWP. On the other hand, exposed seeds by - ray with more than 15 krad., had a grave effect on shoots on this cultivar. Moreover, interaction between WG had insignificant effect on parameters except YI. Eventually, W has been a positive exponential correlation with all parameters at all treatments except SI.
