Evaluation and introduction of promising milkvetch (Astragalus spp.) populations in order to rehabilitate semi-steppe rangelands of Iran (Kurdistan province)

Astragalus spp. are valuable in forage production, soil protection, etc. To evaluate the establishment and growth of herbaceous milkvetch, 10 genotypes, belonging to five species, including Astragalus vegetus. As.brevidens, As. brachyodontus, As. effusus and As. Cyclophyllus, were studied in Sanandaj in a randomized complete block design with three replications. Seed sowing was done in November 2018, and traits of plant establishment percentage, vigor, height and diameter of plant crown, number of branches per plant, average fresh and dry weight of the plant, and the ratio of dry to wet weight of the plant in 2019 and 2020 years was measured. According to the combined analysis of variance, the effects of genotype and year for all studied traits and the interaction of year × genotype were significant (p≤0.01) except for the percentage of establishment and the plant vigor for other traits. Results showed that seed germination, probably caused by seed dormancy or a stress tolerance mechanism, was gradual. In 2020, the mean of plant establishment was about 37%, the number of primary branches was 7.3, plant height and crown diameters were 35.2 and 35.9 cm, respectively, plant fresh and dry weight were 68.2 and 39.1g, and the dry to fresh weight ratio was 0.58. Results of principal component analysis (PCA) showed that two main components (PC1 and PC2) determined 80% of total variance and genotypes with high forage yield located in the third zone of bi-plot with a negative value of PC1 and mainly positive for PC2. In addition, the accession of As. effusus (West Azerbaijan) and three accessions of As. vegetus (Qazvin, Kurdistan and West Azerbaijan) in terms of adaptation and forage production are introduced as high forage yield and adaptable ones for rehabilitation of rangelands in Kurdistan and similar areas in the country.