Study On Polyploid Induction Of Chinese Jujube

By treating shoot-tip with colchicine, three kinds of diploid Z.jujuba Mill. ("Dongzao", "Linyilizao" and "Lajiaozao") were successfully induced into polyploid plants. The cytological, Morphological, biochemical and physiological characters were studied systematically. The major results are as following:1 The optimum combinations of colchicine concentration and treatment duration for different cultivars are different. To the Z.jujuba cv. Linyilizao,2% colchicine and 18h is the best treatment, the induction rate is 46.7%, Z.jujuba cv. Dongzao and Linyilizao are 0.1%/30h and 0.15%/18h respectively, the induction rate are both 43.3%.2 Compare with their original diploid plants, the induced tetraploid plants showed that the leave become longer, wider, and thicker, but the leave index became smaller. And the serration of the leave became larger than the CK., but the serration number per centimeter is less than normal leave. The internode length and lenticel density are smaller than the average.3 Basing on the microscopic anatomic study, the stomata density obviously decreased, the guard cells are larger and the chloroplasts in the guard cells are more than the average ones.4 According to the cytological study , the chromosome number in diploid plants are 2n=2x=24, but in the mutants are 2n=4x=48. Some cell of the induced Z. jujuba cv. Lajiaozao is 2n=2x+2=26. Flow cytometry was used for ploidy determination. From the DNA distribution histogram, the DNA capacity of per diploid is 2C, but the mutant is 4C. In addition, some 8C cells were found in the Z. jujuba cv. Lajiaozao. That is to say that there are some octoploid cells in the chimeral plants.5 From the biochemical and the physiology researches, we found that the pollenfertility of tetraploids plants is less than the average ones. The activity level of the POD decreased but that of the SOD increased.