Studies On Biological And Cytoembryology Of Diploid And Autotetraploid Broccoli

The embryo development and some other biological characters were observed on autotetraploid and diploid broccoli, which laid bases for genetic breeding of polyploid broccoli,The main results were showed as follows:1. Agronomic characteristics,nutritional quality of the diploid and autotetraploid broccoli were studied. The results indicated that curd weight of autotetraploid broccoli higher than diploid, about15.7%; vitamin C content was significantly higher than the diploid, increasing25.6%,soluble proteins and soluble sugar content was higher than that of diploid, dry matter content and chlorophyll a+b content are no significant difference between diploid; autotetraploid broccoli show giant pigmented, Compared diploid,the biggest leaf weight of autotetraploid broccoli increased70.5%,plants height, stem thickness and plant spreading was higher than that of diploid, increasing6.10%、16.5%、12.6%; the maturity of autotetraploid is earlier than diploid5days.2. Traditional paraffin sectioning method was used to observe the development of megasporore and female gametophytes of the diploid and autotetraploid broccoli.The results indicated that the ovary was two carpellum,two locular,parietal placenta and false dissepiment, and one series ovule in per locule.The development of embryo sac was of the polygonum type. The mature ovules were campylotropous with dual-integument and crassinucellate.The single archesporial cell functionsdirectly asmegasporemother cell.The later undergoes meiotic divisions and develops into linear tetrad. The megaspore at chalazal end became a functional megaspore.There were eight nuclears in the mature embryo sac.The autotetraploid broccoli Embryo Sac development was normal which was similar with diploid. There are53.1%and50.5%of the ovules will develop into mature embryo sac respectively of the diploid and autotetraploid broccoli.3. Embryo Sac Structure, fertilization process and embryo development of the diploid and autotetraploid broccoli were studied after self-pollinated in Bud Stage. The results indicated that autotetraploid broccoli Embryo Sac development was normal which was similar with diploid. The frequency of pollen germination of autotetraploid broccoli was lower and the pollen tubes grew slowly and nonuniformly. Both diploid and autotetraploid broccoli gave normal fertilization. Compared with diploids, autotetraploid Embryonic development was later2-3d and embryonic development progress was highly synchronous. Besides this,autotetraploid broccoli had abortive percentage, normal embryo type only account for25.8%. All of these resulted in the seed setting rate of autotetraploid broccoli lower22.6%than diploid.4. Traditional paraffin sectioning method was used to observe the development of megasporore, microsporore, male and female gametophytes.Results showed that Meiotic divisions inmicrosporemothercells are followed by smi ultaneous cytokinesis and result in tetrahedral and decussate tetrads.The male gametophyte development process in diploid broccoli, through which one vegetative cell and one generative cell were produced by one miotic division, and the generative cell would divide into two sperms by the other miotic division and in the end3-celled mature pollen with three apertures was formed. In addition, the ovary was two carpellum,two locular,parietal placenta and false dissepiment, and one series ovule in per locule.the development of embryo sac was of the polygonum type. The mature ovules were campylotropous with dual-integument and crassinucellate. The single archesporial cell functionsdirectly asmegasporemother cell. The later undergoes meiotic divisions and develops into linear tetrad. The megaspore at chalazal end became a functional megaspore.There were eight nuclears in the mature embryo sac.The development of stamen is earlier than that of pistil.