Inside the seed, the embryo is sandwiched between these nutrients, which in turn are enclosed within the protective seed coating. For a number of years, leading forestry scientists have worked on creating an artificial seed that would provide substantial genetic improvement over zygotic seeds.

Artificial seed technology starts with an embryo. A somatic embryo generated from utilizing Somatic embryogenesis 

A process of initiation and development of somatic embryos in vitro from somatic cells and tissues.

technology. Somatic embryos are similar in size, shape, and composition to zygotic embryos, but most somatic embryos lack certain key components required to be stored, processed or germinated.

Specifically, they lack the nutrients and the protective seed coats. This is where the real challenge in artificial seed technology lies.

To overcome this challenge, two general approaches have been developed to germinate somatic embryos. The first utilizes aseptic techniques to germinate embryos on sterilized laboratory growth media in sterile Germination 

A three-phase process starting with uptake of water by a quiescent dry seed, then elongation of the embryo along its axis, then protuberance of a root or shoot radicle through the seed coat.  CLICK FOR MORE

chambers. The second is encapsulation of the embryos in various types of gels which are then sown into growing mixes.

While both have shown great promise for many years, neither approach has been proven practical in commercial environments.

The problems with in vitro germination.
This first approach involves sowing naked somatic embryos onto a sterilized, semi-solid or liquid media that is contained within a solid support such as a Petri dish. This is known as in vitro technology.

These types of proprietary in vitro processes (e.g. US Patent Nos. 5,183,757; 5,294,549; 5,413,930; 5,464,769; 5,506,136) work, but they have serious limitations. Each embryo must be manually handled throughout the germination and transplanting steps. The risk of contamination is high, and the variability in results is wide.

While a number of automated systems have been explored

Roberts et al., 1995.

, none have been found to be commercially viable. Indeed, there seems to be no system that can reliably and cost effectively produce germinated in vitro embryos at large scale volumes for transplanting into conventional propagation systems.

Gel encapsulation.
The second approach for germinating somatic embryos involves the encapsulation of somatic embryos with gels. The end products of these proprietary techniques are various forms of artificial seeds (e.g. US Patent Nos. 4,777,762; 4,957,866; 5,183,757; 5,482,857), which can then be sown into a conventional growing systems using standard seeding technology.

While promising, this too has serious limitations.

First, the process of encapsulation requires sterile conditions in order to reduce the risk of microbial contamination. Second, the semi-solid physical characteristics of encapsulating gels are not compatible with commercial equipment currently used for plant propagation. The embryos tend to clump together during handling, creating difficulty in dispensing, and generally clogging up the equipment.

A final difficulty with encapsulated somatic embryos is their inability to take in nutrients by hydrolyzing large molecules like a Zygotic Embryo 

An embryo derived from the sexual fusion of gametic cells produced by meiosis.

does inside the protective coating of the seed. As a result, the encapsulation technology for somatic embryos includes nutrients such as sugars, fertilizers and oxygen within the encapsulation medium (or gel).

Sakamoto et al. (1995)

Unfortunately, when these encapsulated embryos are germinated in non-sterile environments, they tend to be highly susceptible to microbial invasion during the manufacturing, storage and germination steps.

The most significant problem with artificial seed technologies utilizing encapsulation or other coatings is that germination vigor is substantially reduced, which produces less vigorous plants. Most scientists have concluded (see Carlson & Hartle, 1995) that considerable additional research is required before artificial seed technology has any practical applications. Based on a number of research reports, we expect to see evolutions of this technology which involve a second less permeable layer covering the encapsulation gels.

Carlson, W.C. & J.E. Hartle (1995) Manufactured seeds of woody plants. IN S.H. Jain, P.K. Gupta & R.J. Newton (Eds.) Somatic Embryogenesis  A process of initiation and development of somatic embryos in vitro from somatic cells and tissues.  of Woody Plants. Vol. I. History, Molecular and Biochemical Aspects and Applications. Kluwer Academic Publishers. Dordrecht. Pp 253-263.

CellFor's role in articifical seed technology.
At CellFor, we're optimistic that artificial seed technology will eventually work. When it does, CellFor will provide mass production of somatic embryos for use in artificial seeds.

But we're not waiting for that day to happen.

CellFor has developed a revolutionary system for sowing, germinating and propagating somatic embryos that eliminates most of the issues faced by conventional in vitro techniques.

The end result is a system that allows naked embryos to be sown in volume using conventional seeding technology. What's more, CellFor's somatic embryos can be sown into standard containers or into our proprietary miniplug media, which can then be planted into conventional bare root nurseries utilizing CellFor's proprietary bare root transplanting equipment. Moreover, each of these sowing steps is carried out in conventional horticultural greenhouse environments without the need for a sterile environment or specialized equipment.