EMBRYOLOGICAL STUDIES ON RICE HDAR ──ORIGIN AND DEVELOPMENT OF ADVENTITIOUS EMBRYO

Adventitious embryos were observed in certain frequency (2.72 per cent) inHigh-frequency Diploid Apomictic Rice (HDAR).Their origins were assured to be from nucellar cells in ovule.Early when tile embryo sac was in 2-nucleate or 4-nucleate stage,initial cells of the adventitious embryos started division,and then developed into embryonic structures of multiple cells while the embryo sac was in₈-nucleate stage.Afterwards they went on dividing and squeezing into embryo sac.The adventitious embryocontinued developing with the nutrient offered by endosperm after pollination.Either didthe zygotic embryo continue developing along with the adventitious or degenerated, theadventitious embryos would go on differentiating and eventually develope into matureseed.The possible applications of adventitious embryos developed earlier than zygoticembryo did in rice were also discussed in this paper as well.