This experiment were conducted on the 3 cultivars of potato (Agria, Satina and Caesar) and 4 irrigation regimes (after 30 mm evaporation from class A evaporation pan, after 30 mm evaporation from class A evaporation pan with spraying by potassium humate, after 60 mm evaporation with spraying by potassium humate and after 60 mm evaporation from class A evaporation pan) in 3 locations of Ardabil in northwestern Iran and in 2 years (2007-2008), experimental design was split plot with 3 replications. Potassium humate sprayed (250 ml ha -1) in the 3 stages of emergence, before tuberization and during tuberization period. Combined analysis of variance showed that were significant differences between locations, years, irrigation regimes and cultivars and their interaction on tuber yield. The analysis of variance for the AMMI model of tuber yield showed that environments, cultivars * environments interaction and AMMI component1 were significant. Results show that Agria and Caesar cultivars had high tuber yield in all of sites and 4 irrigation regimes in 2 years, caesar cultivar had the less slop, S.E., MS-TXL, MS-REG and MS-DEV among other cultivars and was the most stable cultivar. The Agria cultivar has adapted in Alarog, Hassanbarog and Khoshkeroud sites under normal and normal with potassium humate conditions, Caesar and Satina cultivars in Alarog, Hassanbarog and Khoshkeroud sites under stress with potassium humate and stress conditions in order to ensure their yield stability and economic profitability.
