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

Abstract

Medicago spp. is the most important forage crop in many regions of the world.<br />Annual medics have distinct advantages over perennial Medicago. These species have faster<br />growth rate in cultivation year, higher crude protein percentage, tolerance to pests and more<br />vigorous seedlings. Morphological and physical aspects of pod and seeds of annual medics<br />play a major role in the tolerance of the plants to over grazing and establishing in different<br />type of rangelands i.e., plants with small seeds can establish better in heavy grazed rangelands,<br />spiny pods establish better in dense compact clay soil, hard seeds increase seed bank of the<br />soil and maintain the pasture for the next years. In order to study the variation in seeds and<br />pods morphological traits of five annual Medicago spp. seeds of 50 accessions of M. rigidula,<br />M. polymorpha, M. orbicularis, M. radiata and M. minima, provided from natural resources<br />gene bank of Iran, were sown in pots. Data were collected for size of the seeds, spins and<br />pods, number of seeds per pod, levels of hardseededness and elevation of the seed origin.<br />Results showed that M. rigidula 1000-seed weight had the most variation. Largest seeds were<br />17 times bigger than the smallest one in this species. M. polymorpha showed the most<br />variation in the elevation of seed origin (upper=2280 m, lower=5 m above sea level). M.<br />radiata showed the most variation in the amount of hard seeds. M. rigidula showed the least<br />amount of hard seeds (mean=59.93). M. radiata had the largest pods. M. radiata and M.<br />orbicularis showed the highest variation in pod size. M. polymorpha showed the highest<br />variation of spine length. The correlation between 1000-seed weight and the elevation of seed<br />origin was positive and significant for M. polymorpha and negative and significant for M.<br />orbicularis. Based on Ward clustering method, the five species were grouped into two clusters<br />in a dendrogram. First cluster included M. minima and M. polymorpha and the second cluster<br />included M. rigidula, M. orbicularis, and M. radiata. This result indicated that it may possible<br />of interspecific hybridization between species of the same cluster.