Evaluation and selection for salinity stress tolerance in Iranian promising alfalfa (Medicago sativa L.) ecotypes

To improve salinity stress tolerance in Iranian promising alfalfa ecotypes, including Shorkat, Gharghologh, Gharaghozloo, Rehnani, Roodasht Isfahan and Gavkhooni, a recurrent selection scheme was carried out at roodasht and kabootarabad field stations, Isfahan, Iran, during 2012-2017 growing seasons. Six Iranian promising alfalfa ecotypes were planted in the autumn of 2012 and irrigated with saline water of 6 to 15 dS.m-1 during spring and summer of the following year. The ecotypes were evaluated in late summer of the same year using phenotypic characteristics of the plants including; stem no.plant-1, plant height, leaf: shoots ratio, and reaction to pests and diseases, and desirable plants were marked and selected from each ecotype. Seed from selected plants of each ecotype were harvested and bulked. Next year, 13 entries including six selected bulk ecotypes, six Iranian promising ecotypes, and one foreign cultivar (Bulldog) were evaluated using randomized complete block design with four replications. Results showed that derivative ecotypes of Gharaghozloo and Rehnani with average forage production of 80.2 and 79.7 ton.ha-1 fresh forage yield, 19.4 and 19.4 ton.ha-1 dry forage yield and average plant height of 61.3 and 62.3 centimeter, respectively, were salinity tolerant ecotypes. The derivative ecotypes of Gharaghozloo and Rehnani had 19.3% and 19.7% protein content, respectively. These derivatives obtained of 9.5 and 5.5 winter dormancy scores, respectively. They only damaged 10.2% and 7% by weevil. Overall, the derivative ecotypes of Gharaghozloo and Rehnani were identified salt tolerant and are suitable for being grown in saline areas and used in alfalfa breeding programs for development of synthetic alfalfa cultivars.