Introduction: Among different abiotic stresses, drought is one of the main inhibiting factors that affects all growth and metabolic processes and ultimately reduces crop productivity. As a plant that is sensitive to drought stress, the performance of potato reduced due to the decrease in the efficiency of photosynthesis, loss of tubers, and reduction in tubers. With the increase of global warming and climate changes, some models show that by 2069, if drought-adapted cultivars are not used in Iran, we will see a 48.3% drop in yields. In a research, two stress sensitivity indices (SSI) and stress tolerance index (STI) were used to determine the drought tolerance of 20 potato genotypes and two genotypes with higher yield were isolated. In a study in Turkey, stress sensitivity index (SSI), stress tolerance index (STI) and yield stability index (YSI) were used to compare the yield of four potato cultivars and the results showed that Atlas and Maranka cultivars had values of 0.61 and 0.67 respectively, had the lowest stress sensitivity index.
Materials and Methods: This research was conducted in the year 2021  at the agricultural and natural resources research station of Rozveh, Chadegan city (longitude 50 degrees 34 minutes east and latitude 32 degrees 50 minutes north) at an altitude of 2230 meters above sea level. To conduct the research, the experiment of split plots used in the form of a randomized complete block design with three replications. The main factor included two levels of irrigation (full irrigation at field capacity humidity as control and irrigation at 75% of field capacity humidity as stress treatment) and the secondary factor included four varieties (Agria, Marfona, Atosa and Anusha). Each plot consisted of four rows of four meters long, in which the distance between and on the row considered 75 and 25 cm, respectively. The aerial organs pruned to thicken the skin of the tuber and prevent injuries during harvesting. The indicators of drought tolerance used in this research were stress sensitivity indices (SSI), stress tolerance index (STI), yield stability index (YSI), mean productivity index (MPI) and geometric mean productivity (GMP). In order to estimate yield and yield components, two meters taken from the middle rows of each plot. SAS software (version 9.1) used to analyze the data, and Duncan's multiple range mean comparison test used to compare the means (at a 5% probability level).
Results and Discussion: The interaction of irrigation factors and variety on yield (total, salable and non-salable) and stress sensitivity indices, stress tolerance index and yield stability index were significant at the 5% probability level and on the average productivity and geometric mean indices at the 1% probability level. By producing 36.20 tons of salable yield per hectare, Atosa cultivar produced 37 and 31% more yield than Marfona and Agria cultivars, respectively, but there was no significant yield difference with Anusha cultivar. The stress tolerance index ranged from 0.48 (Marfona cultivar) to 1.03 (Atosa cultivar) and the average productivity index ranged from 26.67 in Marfona cultivar to 38.82 in Atosa cultivar. Among the four cultivars studied in this research, three cultivars, Atousa, Anousha and Agria, with a yield stability index of 76.90, 78.52 and 78.56% in a statistical group and Marfona cultivar with a yield stability index of 72.87% in a statistical group placed. Usually, cultivars that have higher tolerance to stress (due to morphological and physiological characteristics) also show more stability of performance under stress conditions. The water use efficiency of Agria, Atosa and Anusha cultivars under water stress conditions increased by 20, 18 and 16%, respectively. The results of this research showed that in the range of stresses applied in this study; two new cultivars of Atosa and Anusha have acceptable tolerance to moisture stress and can be included in the cultivation pattern of different regions in Isfahan province.
Conclusion: In all four cultivars tested in this study, moisture stress decreased tuber yield, but the amount of yield loss was different in these cultivars. Two relatively new potato cultivars, Atosa and Anusha, were superior to Agria and Marfona by producing 31.5 and 30 tons of salable yield, respectively. Performance evaluation using stress evaluation indicators shows that the two cultivars of Atosa and Anusha can have a suitable position in the conditions of conventional drought stress (in this study, irrigation of 75% of moisture to the extent of field capacity) in the crop rotations of Isfahan province. Based on the results observed between yield under stress conditions and stress-free conditions with stress tolerance indices, average productivity and geometric mean of these three indices were more suitable for evaluating cultivars than the stress sensitivity index.