Evaluation of Seeds and Pods Variation of 5 Annual Medic Medicago Spp.

Medicago spp. is the most important forage crop in many regions of the world.Annual medics have distinct advantages over perennial Medicago. These species have fastergrowth rate in cultivation year, higher crude protein percentage, tolerance to pests and morevigorous seedlings. Morphological and physical aspects of pod and seeds of annual medicsplay a major role in the tolerance of the plants to over grazing and establishing in differenttype of rangelands i.e., plants with small seeds can establish better in heavy grazed rangelands,spiny pods establish better in dense compact clay soil, hard seeds increase seed bank of thesoil and maintain the pasture for the next years. In order to study the variation in seeds andpods morphological traits of five annual Medicago spp. seeds of 50 accessions of M. rigidula,M. polymorpha, M. orbicularis, M. radiata and M. minima, provided from natural resourcesgene bank of Iran, were sown in pots. Data were collected for size of the seeds, spins andpods, number of seeds per pod, levels of hardseededness and elevation of the seed origin.Results showed that M. rigidula 1000-seed weight had the most variation. Largest seeds were17 times bigger than the smallest one in this species. M. polymorpha showed the mostvariation in the elevation of seed origin (upper=2280 m, lower=5 m above sea level). M.radiata showed the most variation in the amount of hard seeds. M. rigidula showed the leastamount of hard seeds (mean=59.93). M. radiata had the largest pods. M. radiata and M.orbicularis showed the highest variation in pod size. M. polymorpha showed the highestvariation of spine length. The correlation between 1000-seed weight and the elevation of seedorigin was positive and significant for M. polymorpha and negative and significant for M.orbicularis. Based on Ward clustering method, the five species were grouped into two clustersin a dendrogram. First cluster included M. minima and M. polymorpha and the second clusterincluded M. rigidula, M. orbicularis, and M. radiata. This result indicated that it may possibleof interspecific hybridization between species of the same cluster.