Artificial seed production in alfalfa (Medicago sativa L.)

Alfalfa (Medicago sativa L.) is one of the most important forage grasses in the world that plays the main role in animal feeding. It is cross pollinator and as its autotetrapleoidy and self-incompatibility, production of alfalfa cultivars with high yeild, by conventional method, is difficult. Among the wild species and also in alfalfa cultivars, it can be sometimes observe the elite genotypes, which have many good traits, and maintenance and increasing of these elit genotypes by production of pure desirable seed are difficult. One of the most effective techniques, in this case, is artificial seed production. In fact, artificial seed (also referred as synthetic seed or somatic seed) technology is one of the most rapidly developing fields of plant science in the last decade. They are generally prepared by encasing the somatic embryos obtained from tissue cultures in a protective jelly capsule, which is usually prepared with sodium alginate, or by desiccating the somatic embryos with or without coating. The aim of this project, was to show the ability of alfalfa artificial seed production in Iran. Different induction media [ SHK, four modified SHK media, B5h1 and B5h2], was tested for embryogenic callus induction and modified SHK medium with 4350mg K2SO4 (SHK4 medium), was the best. Among the 13 tested cultivars of alfalfa, only the Ranglander genotype, was embryogenic one. In order to proliferation of embryogenic calli, 9 treatments were used,and the modified B5 medium with 10% maltose, 10% soucrose and 0.5 mg/L 2,4-D was the best. Study of the maturation and desiccation phase of somatic embryos were done using, 4 levels of absisic acid (ABA) (0, 0.5, 1, 3 and 5mg/L) in Bio2Y II basal medium with different culture times(3, 7, 14 and 21 days), and with 4 treatments for somatic embryos desiccation(0, 1, 3 and 5 days). At the end of this stage, ABA (3mg/L) with 5 day maintenence of embryos in Bio2Y II medium and 3 days desiccation showed the best rate of germination and conversion. Two kinds of sodium alginate, LF and LB (0.5, 1.5, 2, 3 and 4%) was tested for encapsulation of dried somatic embryos. The best concentration of sodium alginate for germination of encapsulated embryoes in both in vitro and in vivo conditions, was 2% of LF type .