| Different maize genotypes were used as the experiment material, according to their physical character. Sand culture experiment in lab is major and field culture is assistant. Changes of physiological character and ultrastructure of different period is studied in system by ultrathin-sectioniing method and biology electron microscope. The research is conducted in Shandong Agricultural University and the experiment farm from 2001 to 2002.the main results were as follows:1 Regular of physiological character of different genotype of maize during seed-seedling transformationWith germination time going, storage starch, crude fat and storage protein in maize seed decomposes gradually, the structural substance increased constantly. Embryo entity mainly synthesizes structural substance, and its weight increases gradually. The content of soluble sugar in endosperm and scutellum firstly rises and then declines, while the content of soluble sugar in embryo entity firstly declines, then rises, at last declined again. The protein content in endosperm, scutellum and embryo first rises and then declines. The free amino acid content in endosperm and in scutellum also first rises and then declines, while the content of free amino acid in embryo always rises.2.Difference of physiological character of different genotype of maize during seed-seedling transformationWith the germination time increasing, changes of storage substance in different maize show difference. The smaller type seed breed LYD14 decomposes and utilize the storage substance quickly than the larger type seed breed YD22 in the earlier period and slowly than YD22 in the later period during seed-seedling transforming. Farinaceous endosperm breed LD50' efficiency of decomposition and utilization of storage substance is higher than keratin endosperm breed ND108. The larger size seed YD22' efficiency of decomposition and utilization of storage substance is higher than the smaller size seed YD22' . The weight of endosperm and scutellum of the larger size seed YD22 decreased quickly than the smaller.The difference of physiological character of different genotype during seed-seedling transformation also can be translated from the aspect of enzymology. During seed germination, endosperm and scutellum as the storage organ and embryo entity as the growing organ, come into being source-sink relationship. The storage organ is the nutritional source of the growing organ. The content and decomposing ration of storage substance affect the growing organ' growth. The main storage substance in maize seed is starch, protein and crude fat. So starch hydrolytic enzyme, protein hydrolytic enzyme and fat hydrolytic is the key enzyme in maize germination. Starch and crude fat can be the carbon source of maize seedling after decomposed. Amino acid is the main material of making new issue. The research shows the experimental material which can quickly use storage substance, activity of hydrolytic enzyme is high. High activity of the hydrolytic enzyme' s canquickly offer soluble sugar and free amino acid, so the innovans tissue can get nutrient quickly. Seedling can favorably shift to autoruophy from allotrophy, which has important action to seedling's healthy growth.The energy level in different period has close relation to physiological change during seed-seedling transformation. The embryo's budding and the seedling's growth not only need nutrient, but also need plenty of biology energy. The content of ATP in endosperm, scutellum, embryo of the smaller type breed LYD14 than in larger type breed YD22 in earlier period, and lower than YD22 in later period. LD50's ATP content in endosperm and scutellum is high than ND108's. The both sides' have little difference in their seedling in earlier period, but 16 days after germination, LD50's ATP content in seedling increases evidently, and ND108's decreases. The lager size seed YD22 has more ATP in storage organ especially in endosperm than the smaller size seed YD22. The content of ATP in embryo entity is mor... |
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