Study On Development Of Caryopsis And Accumulation Storage Substance In Oat

The development of the caryopsis for two types of oats, husk and naked oats,were studied in this thesis by using anatomical and histochemistrical methods, and the accumulation of main storing substances, starch, protein, lipid andβ-glucan in the grains were studied as well in the thesis.The results demonstrated the oat seed development is of the typical characteristics of gramineae plant seeds in morphological respects, being with gramineae type of embryo development, nuclear endosperm. The outmost two layers of cells in endosperm formed aleurone layer, and pericarp was developed from the inner integument and ovary intraepidermal growing. The detailed development process of naked oat could be described as follow: at day 1 or day 2 after anthesis, zygote started the first mitosis, and forms two cells of proembryo; two or three days later, it formd four cells of proembryo, and endosperm got in free nuclear stage. Four to seven days later, proembyro cells continually divided, respectively passing by club shaped proembyro stage, ellipse proembyro stage, and pear forms proembyro stage, in this period, endosperm grew into the cellularization stage. Up to seven to eight days, proembyro developed into the differentiation stage. Nine to ten days, scutellum and coleoptile were separated, and the first leaf primordium was differentiated, aleurone layer was differentiated from endosperm. Ten to fifteenth days later, the second, third and fourth leaf primordium , were formed, in twelve to thirteen days after the anthesis, starch endosperm cell had been filled with the starch particles, and in forteen to fifteen days, the differentiation for all organs in embyro had been completed, the nuclear and wall of starch endosperm are disintegrated gradually. Fifteen to twenty-five days later after anthesis, embryo matured, and endosperm matured too. The results laso showed that embryo developed earlier for husk oat than for naked oat, however, it's aleurone layer differentiated later than naked oat's. For husk oat, after two to three days of anthesis, club shaped proembyro was formed, three to four days later, it grew to pear type embryo, and after five to six days of anthesis, it developed into embryo differentiation stage, when seven to eight days after anthesis, first cotyledon, external cotyledon in the embryo were differentiated; nine to ten days later, the third leaf primordium had been formed, and the embryo differentiation had been completed; after nine to twelve days of anthesis, endosperm aleurone layer started differenting; from then on, ten to eighteen days later, all parts of embryo continued growing, and the volume also enlarged gradually until maturation. Up to twenty days, starch endosperm cells start disintegrating; thirty days later, aleurone layer still continuously grew, forming two orderly aleurone layers.The results about time courses of starch, protein, lipid, andβ-glucan contents in hulled and naked oat grains during seed development stage showed that from anthesis to grain matured absolutely, the starch percentage of the grains presented a increasing S-curve, and the peak of starch accumulation velocity was at middle grain filling stage, the starch content in hulled oat is higher than naked oat; the protein percentage presented parabola with upward open, at 12th day after anthesis, it reduced to the lowest point, the protein content in hulled oat is significantly less than naked oat; the lipid percentage presented parabola, with downward open, at 20th day, it increased to the highest point, the lipid content in hulled oat is slightly more than naked oat; andβ-glucan percentage increased with time in S-curve, theβ-glucan content in naked oat is more than hulled oat.