Evaluation of genetic variation and relationships of forage yield and its components in different populations of five forage species of milkvetch (Astragalus spp.) in Kurdistan province

To evaluate the genetic diversity and relationships among traits of herbaceous milkvetch, 10 genotypes belong to five species including Astragalus vegetus. A. brevidens, A. brachyodontus, A. effusus and A. cyclophyllus in Sanandaj in a randomized complete block design with three replications were studied. Seed sowing was done in November 2018 and morphological traits of plant in spring 2020 were measured. Analysis of variance released significnant (p≤0.01 and 0.05) difference for milkvetch populations (G) for all studied traits. In 2020 (two years old plants), the mean of plant establishment was about 26%, the number of primary branches was 3.2, plant height, the tallest stem length and crown diameter were 16.9, 19.2 and 15.4 cm respectively, the length and width of the root were 17.4 and 6.2 cm, respectively, the average of fresh weights of the whole plant, arial and root parts were 2.3, 1.9 and 0.4 g and the average of dry weights of the whole plant, arial and root parts were were 0.9, 0.7 and 0.2 g respectively, average dry to fresh weight ratio was 0.38. Average of leaflet per leaf was 7.7, so mean of length and width of leaf and leaflet were 7.5, 3.7, 2.3 and 0.5 cm respectively. Up to this stage, the accession of A. effusus Darreh Shohada (West Azerbaijan) and three accession of A. vegetus (Zereshk of Qazvin, Saral of Kurdistan and Qarehbagh of West Azerbaijan) were superior ones in terms of forage production and other studied traits. The weight of the plant was positively correlated with plant vigor, length and width of leaf (p≤0.05) and with plant height, crown diameter, number of primary branches, length and width of root, arial and root weight at 1% probality level. The results of stepwise regression of forage yield on other traits showed that plant weight, establishment percentage, plant height and crown diameter at 1% and the length of leaf and root at 5% probality level (R2adj = 91.1%) were forage yield components. Therefore, in order to achieve higher forage, the genotypes with larger aerial parts and deeper roots should be selected.