Evaluation of Drought Tolerance of Potato (Solanum Tuberosum L.) Under Water Deficit

Potato is considered as a strategic product in the food security of the country and is the fourth most consumed food product in Iran.  Due to its shallow rooting system, this plant is sensitive to water deficit.  In order to study the response of 20 potato genotypes to drought stress, a field experiment was conducted during 2018–2019 at the Seed and Plant Improvement Institute located at Karaj, Iran. The experimental design utilized was a Strip-plot based on randomized complete block design with three replications under two irrigation regimes (normal and stressed). ANOVA showed a significant difference for genotypes at 1% level for overall tuber yield, ware yield (tubers larger than 35 mm), seed yield (tubers between 35 and 55 mm), small yield (non-marketable potatoes), and marketable yield (total ware yield and seed yield). Eleven drought tolerance indices including STI, SSI, TOL, HARM, GMP, MP, YSI, DSI were calculated based on tuber yield under water deficit (Ys) and irrigated (Yp) conditions.  Our results showed a highly significant and positive correlation between MP, Yp and Ys.  The results of the analysis of PCA and the analysis of clustering showed that the drought-tolerance and drought-sensitive genotypes with the clustering pattern are consistent.  The MP, GMP, STI and MSTI identified 902027 genotypes as the best genotype under normal and stress conditions.  Among the genotypes and cultivars studied, 902027 and 8703- genotypes showed the highest MP and GMP, indicating high stability of genotypes in response to drought stress and thus can be considered as drought tolerant genotypes.