Study On Bud Development And Embryology Of Fraxinus Mandshurica Rupr.

The paper studied the process of bud development and some embryology content of Fraxinus mandshurica by outside observation and paraffin section, it primarily includes the process of floral bud and branch bud development, the scientific study of periodic biological phenomena, fertilization, the development of embryo and endosperm ,etc. The main results can be concluded as follows:1. There are six stages of male floral bud differentiation: Inflorescence primordium differentiation stage, Bract differentiation stage, Male flower primordium differentiation stage, Stamen primordium stage, Stamen differentiation stage and Male flower mature stage.2. There are six stages of female floral bud differentiation: Inflorescence primordium differentiation stage, Bract differentiation stage, Female flower primordium differentiation stage, Pistil primordium stage, Pistil differentiation stage and Female flower mature stage.3. There are six stages of branch bud development: Undifferentiating stage, Shoot bud primordium stage, Compound leaf primordium stage, Vascular bundle differentiation stage, Vascular bundle formative stage and axillary bud primordium formative stage.4. Double fertilization is the type of the premitotic gametogamy. A sperm and egg cell fusion formation of homozygous; another sperm and secondary primary endosperm formation of a nuclear fusion.5. The development of embryo belongs to solanad type. The fertilized egg usually underwent a rest period about fifteen days before embarking on its first division. And the first division of the zygote took place after the division of primary endosperm nucleus. After the club-shaped embryo, the globular embryo, the heart-shaped embryo and the fish-torpedo embryo, the cotyledon-shaped embryo developed when the fruit became ripe. At the globular embryo stage, the suspensor was well developed. From the late globular to early heart-shaped embryo stage, the suspensor grew to its minimum length.6. The endosperm development of Fraxinus mandshurica was cellular type. The primary endosperm nucleus division was often prior to zygote, and it divided quickly. The endosperm cells surrounding the embryo were disintegrated during the development of embryo.7. We analyzed the relationship not only between the flower bud size and internal Structure but also the key fruit size and development stage of embryo and endosperm.