Embryo culture of interspecific hybrids in the genus oryza

An embryo culture technique has been standardized for raising to maturity, hybrid seedlings from several interspecific crosses which are otherwise impossible to obtain in the genus Oryza. In this method, the 10–25 days old hybrid seeds were surface-sterilized for 15 to 30 minutes in cold, saturated, clear solution of calcium hypochlorite, followed by a rinsing in sterile, distilled water. The aseptically excised embryos or the ovaries were planted on White's or Nitsch's agar medium containing 10 per cent. coconut milk and 0.l per cent. malt extract. After the seedlings had grown fully in the above medium, they were removed out of the culture tubes and given a ‘hardening’ treatment in petri dishes over moist filter paper for a week or more before planting in soil. However, the alternative method of rearing the seedlings in a nutrient solution after their growth on agar medium for a period of 10–12 days gave almost complete success in ensuring vigorous growth of the hybrids.