The in vitro response of California Rock hybridwas tested using hypocotyls and leaf disc as an explants source for callus induction at different cytokinin types
( KIN – BAP - TDZ) with different concentrations ( 0.0 -0.5 – 1.0 – 2.0 mg/l ). Callus formation was noticed at all treatments, BAP was the most effective one followed by TDZ, the lowest values were obtained by KIN. Concentration at 1.0 mg/l recorded the greatest values. Hypocotyls was better than leaf disc for all recorded data. All treatments gave hard callus and didn't promote any shoots. No root was noticed with KIN or BAP at 2.0 mg/l with hypocotyls for each. TDZ at ( 0.5 – 1.0 – 2.0 mg/l) with any explants gave negative results to root formation. BAP at 1.0 mg with hypocotyls was the most effective one being  recorded the highest values of callus i.e. ( volume , fresh and dry weight ).