Abstract
Studies on development in vitro of excised ovaries in the interspecific crosses between Brassica campestris L.ssp. pekileensis (Lour.) Olsson cv. Nozaki-hakusai and Brassica oleracea L.var. capitata L. cv. Nozaki-wase and cv. Nozaki-nakate, and in the sibmates of the two species were carried out. Development ile vitro of the ovaries excised fcur days after pollination was studied at various culture media with yeast extract and casein hydrolysate, which were added either separately or in various combinations. (1) In the sibmate of B. campestris, many seeds Results obtained were as follows. (2) In the sibmate of B. oleracea, seed set in were obtained in all the media used. the capsules was low in all the media used. (3) In the interspecific crosses of B. caleapestris x B. oleracea (Nozaki-hakusai x Nozaki-wase and Nozaki-hakusai x Nozaki-nakate), seeds and well developed naked-embryos protruded from undeveloped seed coat were obtained in the capsule. Production of seeds and the naked-embryos was best in the medium with 300mg/l of casein hydrolysate. These naked-embryos were also obtained in the basic medium. Developmental stale of the naked-embryos obtained in the capsule was from torpedo-shaped to full-grown embryo. Seven of 49 embryos further cultured and were proved to be hybrid. Two of 7 seeds obtained grew and also showed hybrid. No difference in morphological characteristics of leaf and inflorescence was observed among them.(4) In the reciprocal cross, B. oleracea x B. campestris (Nozaki-wase x Nozaki-hakusai and Nozaki-nakate x Nozaki-hakusai), no seeds and no developed naked-embryos were obtained in all ovaries cultured. (5) Culture in vitro of excised ovaries is useful as a new technique for production of interspecific hybrids in Brassica campestris x Brassica oleracea.
