Cytogenetic study on several populations of diploid species of Onobrychis in natural gene bank of Iran

The genus Onobrychis Adans. (Fabaceae) is an important forage crop, containing  approximately 342 annual and perennial species. Video Analysis System was used for karyotype analysis on 21 populations of 14 onobrychis species. The basic chromosome number varied between x=7  and x=8 but their chromosomal variation was very high. According to Stebbins' classification, populations  O.hohenackeriana (6013) and O.gypsicola (1111) classified as symmetric class of B and others as A. The highest VRC was obtained for O.amoena (5786) and the lowest was obtained for O.crista-galli (2520) populations. Based on inter chromosomal symmetric, O. crista-galli (2543) had the most asymmetrical and evolutionary karyotype and O.aucheri (2900) had the most symmetrical karyotype. Based on intra chromosomal symmetric, O.hohenackeriana (6013) had the most asymmetrical karyotype. The results of analysis of variance based on unbalanced completely randomized design showed significant differences among the populations for all the studied traits (P<%1). Using principal components analysis, the first two components justified %98.36 of total variance. In the first component, chromosome total length, long arm length and short arm length which had the highest coefficients of eigen vectors also, had the most significant role in total variance. In the second component arm ratio and centromer index had the most important role in the total variance. By cutting dendrogram resulted from cluster analysis (Ward) with cophenetic value equal to r=0.78 based on the 5 parameters (TL, LA, SA, AR, CI,) the populations were classified to four classes. The highest distance was obtained between O.amoena(5786) and O.melanotricha (2863). The lowest metric distance value was obtained between two populations of O.sintenisii (4384) and (1183).