Determination of fall dormancy score of Iranian alfalfa (Medicago sativa L.) ecotypes in cold and temperate climates

To evaluate fall dormancy of twenty alfalfa local ecotypes and exotic cultivars, this study was conducted in two separate experiments (conventional or dense planting and spaced planting) using randomized complete block design with three replications in three growing seasons 2014, 2015 and 2016 in two locations (Karaj and Khoy), Iran. First growing season was considered as estabilishment season. Three ecotypes of Hamedani population, four ecotypes of Gharah-Yunjeh population, five ecotypes of warm region populations, two ecotypes from central part of the country and six exotic cultivars were included in this study. In conventional planting, each cultivar/ecotype was grown in two rows of 5 m length and 50 cm row spacing using 20 kg.ha-1 seeding rate, based on seed germination percentage. In spaced planting, each cultivar/ecotype was planted in two rows of 5 m length and 50 cm row spacing and 50 cm distance between plants on row. The recorded traits were plant height, stem number per plant/m-2, dry forage yield, and fall dormancy score. Combined analysis of variance of both experiments showed that mean squares of cultivar/ecotype was significant for dry forage yield, plant height and fall dormancy score. Genotype × location interaction efect was also significant for these traits. Mean comparison of dry forage yield of cultivars/ecotypes showed that Baghdadi with 15.02 t ha-1 and Kiseverdai with 12.3 t.ha-1 in conventional planting, and Bami-1 with 29.6 g.plant-1 and Sequel with 22.1 g.plant-1 had the highest and lowest dry forage yield over two locations and growing seasons, respectively. In both experiments, the local ecotypes related to warm region had the higher fall dormancy scores in comparison to ecotypes from cold region. In conventional planting, Nikshahri, Bami-1 and Baghdadi with 6.9, 6.8 and 6.7 scores, and in spaced planting, Baghdadi and Nikshahri with 6.1 and 6.0 scores showed the highest fall dormancy scores, respectively. Commandor had the lowest fall dormancy score with 3.5 and 3.3 in conventional and spaced planting experiments, respectively. In general, the fall dormancy scores were determined in ecotypes of Ghara-yunje and Hamedani populations (cold region) from 4 to 5, ecotypes from temperate region (KFA7 and Yazdi) from 6 to 7 and warm region (Bami, Baghdadi and Nikshahri) from 7 to 9 scores. Assessment of fall dormancy scores in conventaionl planting experiment led to better estimates, however, it did not affect the grouping of cultivars/ecotypes.