University of Tabriz Journal of Agricultural Science and Sustainable Production 2476-4310 Articles in Press 2027 01 21 Evaluation of Drought Stress Tolerance Indices in Different Genotypes and Ecotypes of Alfalfa Evaluation of Drought Stress Tolerance Indices in Different Genotypes and Ecotypes of Alfalfa 20973 10.22034/saps.2025.64799.3315 FA Parisa Moradiyan Ph.D. Candidate of Plant Breeding, Departement of Agronomy and Plant Breeding, Faculty of Agriculture and Natural resources, Tabriz Branch, Islamic Azad University, Tabriz, Iran Hassan Monirifar Associate Professor, Horticulture and Crops Research Department, East Azarbaijan Agricultural and Natural Resources Research and Education Center, AREEO, Tabriz, Iran Varharam Rashidi 3Associate Professor, Departement of Agronomy and Plant Breeding, Faculty of Agriculture and Natural resources, Tabriz Branch, Islamic Azad University,Tabriz, Iran Bahman Paseban Eslam Paseban Eslam Associate Professor, Horticulture and Crops Research Department, East Azarbaijan Agricultural and Natural Resources Research and Education Center, AREEO, Tabriz, Iran Journal Article 2024 11 30 Background and Objective: The selection of high-yielding and stable cultivars for each region, particularly under water-deficit conditions, is crucial for sustainable forage production. This study aimed to assess the drought tolerance of different alfalfa (Medicago sativa L.) cultivars and ecotypes based on yield performance under limited irrigation conditions.<br />Materials and Methods: The experiment was conducted using a split-plot design within a randomized complete block design (RCBD) with three replications at the research station of the East Azerbaijan Agricultural and Natural Resources Research and Education Center, located in Khosrowshah, over three cropping years (2015–2017). The main plots consisted of three irrigation levels: irrigation termination after the first, second, and third harvests. The subplots included seven genotypes: three synthetic cultivars (Synthetic A, Synthetic B, and Azar) and four ecotypes (Joshan, Satlu, Khajeh, and the local control ecotype of Khosrowshah).<br />Results: Combined variance analysis indicated significant differences between years and stress levels for all morphological traits. The number of stems per plant, fresh leaf weight, dry leaf weight, fresh stem weight, and dry stem weight significantly decreased under severe drought stress conditions. Based on drought tolerance indices, the Synthetic A and Synthetic B cultivars, along with the Joshan ecotype, were identified as drought-tolerant genotypes.<br />Conclusion: Overall, the indices MP, GMP, STI, and HM can be effectively used for drought tolerance screening and for identifying superior genotypes under both stressed and non-stressed field conditions in alfalfa. The results identified the Joshan ecotype as the most drought-tolerant ecotype in this study. Background and Objective: The selection of high-yielding and stable cultivars for each region, particularly under water-deficit conditions, is crucial for sustainable forage production. This study aimed to assess the drought tolerance of different alfalfa (Medicago sativa L.) cultivars and ecotypes based on yield performance under limited irrigation conditions.<br />Materials and Methods: The experiment was conducted using a split-plot design within a randomized complete block design (RCBD) with three replications at the research station of the East Azerbaijan Agricultural and Natural Resources Research and Education Center, located in Khosrowshah, over three cropping years (2015–2017). The main plots consisted of three irrigation levels: irrigation termination after the first, second, and third harvests. The subplots included seven genotypes: three synthetic cultivars (Synthetic A, Synthetic B, and Azar) and four ecotypes (Joshan, Satlu, Khajeh, and the local control ecotype of Khosrowshah).<br />Results: Combined variance analysis indicated significant differences between years and stress levels for all morphological traits. The number of stems per plant, fresh leaf weight, dry leaf weight, fresh stem weight, and dry stem weight significantly decreased under severe drought stress conditions. Based on drought tolerance indices, the Synthetic A and Synthetic B cultivars, along with the Joshan ecotype, were identified as drought-tolerant genotypes.<br />Conclusion: Overall, the indices MP, GMP, STI, and HM can be effectively used for drought tolerance screening and for identifying superior genotypes under both stressed and non-stressed field conditions in alfalfa. The results identified the Joshan ecotype as the most drought-tolerant ecotype in this study.