Androgenic haploids
Androgenic haploids of some species, such as wheat, mustard and tobacco, can also be raised through isolated microspore pollen culture (Pollen cultures). It must be realized that in spite of serious efforts androgenic haploids have not been possible in many other economically important plants. In-vitro gynogenesis is another approach to produce haploids (Yang and Zhou, 1990). In this technique unfertilized ovules are cultured on media which stimulate the egg (parthenogenesis) or any other haploid cell of the embryo sac (apogamy) to undergo embryogenic development without fertilization. In-vitro gynogenesis, first observed in Hordeum vulgare by San Noeum (1967), has now been reported in at least 16 species. This technique of haploid production is especially useful in plants in which the androgenic response is unsatisfactory, a large proportion of pollen plants are non-haploids or albinos, as in many cereals.