Collection, identification and evaluation of Medicago genetic resources for conservation and utilization.

Alfalfa (Medicago sativa) is the most important forage crop in the country. Origin of the cultivated and tetraploied ones is valleys of Zagros and Alborz mountains ranges as well as oases in central to South of Iranian Platue. Therefore, Iran is one of the most important centers of genetic diversity in Medicago. According to this project, Medicago genetic resources were collected based on IPGRI descriptors from 27 provinces all over the country. Seed samples after collection with identification forms were sent to National Plant Gene Bank of Iran for conservation and characterization. A total of 1957 accessions were collected. In comparison with old collection of Medicago, it was shown a 448% increasing in the number of accessions (437 to 1975 accessions). Totally 18 species were collected which with other ones in the old collection it up to 20 species. Alfalfa, M rigidula, M minima were the large collections with 701, 230 and 159 accessions, respectively. In addition, M polymorpha, M lupulina and M orbicularis with more than 100 accession had a large number collection. Altitude of collection sites differed from -12 m in Noor (Mazandaran) for M. polymorpha to 2838 m in Kerman for M rigidula and M coronata. A total of 1564 accessions were planted in the field for characterization of argo-morphological traits according to IPGRI descriptors. A high diversity was seen which is discussed for each species separately. In the wild species, 398 accessions had semi-erect in growth habit trait and no one showed the erect growth habit. Yield potential differed from very low to very high and more than 200 accessions had high yield potential. Days to flowering differed from 30 to 105 days, therefore there was a possibility for grouping wild species germplasms under early, moderate and late repining. Correlation coefficients showed that growth habit trait has significant correlation with yield potential and number of seeds per pod, with a coefficient of 0.396 and -0.277, respectively. Cluster analysis grouped wild species according to agro-morphological traits. Therefore, those species which had the same agronomic potential came to gather so in the utilization of these species for agronomic system it should be considered. A high amount of diversity was seen for most of traits in the alfalfa collection (cultivated ones). Plant height at 50% flowering differed from 20 to 99 cm with a mean of 66.4 cm. The mean of regrwth rate acquired from 0.31 to 3.69 cm/day. 32 accessions were tolerate to semi tolerate to alfalfa weevil which were mainly wild types of alfalfa. Multiple regression result showed that plant height and growth habit had linear correlation with susceptibility to alfalfa weevil. Cluster analysis distinguished cold temperate accessions from subtropical ones. Planting of 457 accessions of alfalfa in the Iranshar in order to identifying warm tolerance in the alfalfa collection revealed that only 120 accession could tolerate the summer heat and remain alive, whereas others dead from high stress condition. Those accessions, which had been collected, from Arak, Ferdous, and Qum remain alive whereas the accessions with cold temperate origin mainly were disappeared. All of accessions were regenerated in the field and the seeds delivered to seed lab. Results of this research revealed a unique collection of Medicago in the world that can be used in Medicago breeding programs.