| Chinese jujube (Ziziphus jujuba Mill.) originated in China belongs to Ziziphus genus, Rhamnaceae family.In the long history of Chinese jujube cu1ture practice in China,the most abundant gemrplasm resources in the world were formed. It's the first dry fruit plants and has the greatest economic value and the most wide distribution in Ziziphus genus. Wild jujube (Ziziphus spinosus Hu.) is used as the rootstock for Chinese jujube and important Chinese medicinal material. There are about 700 cultivars in our country, but now only a little dominating cultivars,which had been applied to cu1ture practice, has not been satisfied the demand which people demand the diversified and high-grade jujube cultivars. Too small flower, the low rate of fruit-set and embryo abortion in early stage lead to the difficulties of removing stemina, hand pollination and obtaining hybrid descendents.Germplasm enhancement of Chinese jujube fall behind the other fruit plants.The cytology of Chinese jujube and wild jujube were studied in this research thus provide a cytological basis to its origin, phylogenetics, genetic relationships, Germplasm enhancement and utilization .The main results were as follows:1. Wild jujube and'Zanhuang Dazao'as experimental materials in this research were used to observe the meiosis course of pollen mother cells, and the various periods of the meiosis were described and analyzed. The results showed that wild jujube accorded with the separatist rule of the meiosis with diploid. The meiosis of'Zanhuang Dazao'was irregular. The diakinesis appeared univalent,bivalent and trivalent. The lagging chromosomes were observed in anaphase I and II. Finally there produced triad,tetrad , pentad, hexad, and formed unequal spores.2. Due to the characteristics of small chromosome for Chinese jujube and saving time of the slide preparation, the methods of eliminating walls by enzymolysis and low osmosis were optimized and procedure were as follows:At 9:00 am(about 25℃) in sunny day,about 1～2cm new shoots at the tree top position were sampled and then pretreated with 0.002M 8-Hydroxyquinoline solution and lasted 1～2 hours at room temperature (about 25℃), 8-Hydroxyquinoline solution were poured out and 0.075M KCl solution were infunded and lasted 30 minutes at room temperature for early low osmosis, 0.075M KCl solution were poured out and Carnoys solution were infunded and lasted 24 hours, Carnoys solution of materials were eliminated with distilled water several times, then cell walls of about 1～2mm stem tip were digested with 2.5% mixed enzyme solution for 3～4 hours at 25℃. Stem tip digested with enzyme solution were immersed with redistilled water for late low osmosis 15～30 minutes, then cell of tem tip were smeared at the slides with fire drying then stained with Giemsa.3 Chinese jujube cultivars of diploid were used to observe the mitosis course of cells and the various periods of the mitosis were described. The results showed that they accorded with the separatist rule of the mitosis with diploid. The lagging chromosomes were not observed in anaphase.But nucleolus still existed in prophase and metaphase until anaphase.4 The methods of eliminating walls by enzymolysis and low osmosis were used to study the chromosome karyotype of 11 jujube cultivars and the chromosome number of 8 jujube cultivars and wild jujube. The results showed that the chromosome number of 19 jujube cultivars and wild jujube were 24. The chromosome of 11 jujube cultivars consisted of median point chromosome, median region chromosome, submedian region chromosome. The karyotype asymmetry type consisted of 1B, 2A and 2B. The genetic relationship of Chinese jujube cultivars which belong to the same karyotype asymmetry type were close.By basic karyotype and the karyotype asymmetry, evolution of cultivars were analyzed and it was found that there were several evolutionary paths among cultivars.
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