University of Guilan Caspian Journal of Environmental Sciences 1735-3033 2026 02 18 Indices of tolerance and sensitivity to water deficit stress in different cucumber genotypes. 1 10 9453 10.22124/cjes.2026.9453 EN Mohammadreza Mohammadpour Department of Horticultural Sciences, University Campus, University of Guilan, Rasht, Iran Jamalali Olfati Department of Horticultural Sciences, University Campus, University of Guilan, Rasht, Iran Mohammadreza Khaledian Department of Water Engineering, Faculty of Agricultural Sciences, University of Guilan, Rasht, Iran & Department of Water Engineering and Environment, Caspian Sea Basin Research Center, Iran Babak Rabiei Department of Plant Production and Genetic Engineering, Faculty of Agricultural Sciences, University of Guilan, Rasht, Iran Journal Article 2026 02 18 To identify genotypes tolerant to water stress and screen the tolerance and sensitivity indices to water stress, the present study was conducted in 2022 in the greenhouse of the Faculty of Agricultural Sciences, University of Guilan, Rasht, Iran. The study included 50 cucumber genotypes in split plots and a completely randomized basic design with two levels of irrigation: full irrigation and deficit irrigation (50% of the water provided in full irrigation), each with three replications and two plants per replication. Based on the yield observed under both full and deficit irrigation conditions, various indices were calculated to assess tolerance and sensitivity to water stress. These indices included SSI, SI, HM, TOL, MP, YSI, GMP, STI, MRP, YI, REI, and SRI. The results of the mean comparison indicated that genotype 42 achieved the highest yield under full irrigation, while genotype 45 produced the highest yield under deficit irrigation. The highest values for MP, MRP, REI, STI, GMP, and HM indices were recorded in genotypes 45, 42, 43, and 22. The correlation test results also indicated that these six indices had the highest correlation with yield under both full and deficit irrigation conditions, making them the most suitable indices for screening and identifying superior genotypes. Using various methods in the present study, such as three-dimensional diagrams, principal component analysis, and cluster analysis, genotypes 45, 43, and 42 were identified as superior for achieving high yield under water scarcity conditions. Given Iran's water crisis and its exacerbation by climate change, breeding cucumber cultivars resistant to deficit irrigation is crucial for developing new hybrids suitable for the Iranian environment. https://cjes.guilan.ac.ir/article_9453_3ea89b8d2f9e8ac15ae7c434f5e10fe4.pdf