Studies On Creation And Biological Character In Cold-tolerance And Late-bolting Autotetraploid Non-heading Chinese Cabbage(Brassica Campestris Ssp.chinensis Makino)

This paper is done on autotetraploid non-heading Chinese cabbage from induction, identification, physiological and biochemical response to cold stress and nutrition. It serves as a solid theoretical fundamental and guide of polyploid breeding of non-heading Chinese cabbage.1. Tetraploidy plants of non-heading Chinese cabbage (B rassica cam pestris ssp. chinensis Makino) were induced by treating the apical portion of seedlings with different solution of colchicines. Autotetra ploid plants were selected and identified based on morphological, anatomic, agronomic,cytological observation and flow cytometry. The results showed that the treatment with 0.2%colchicine for 4 times yielded doubled chromosome at highest rates and the rate of tetraploid was 8.42%. Compared with the diploid, the autotetraploidy plants possessed gigantism in plant,stomata flowering organs. The density of stomata and fecundity were receded remarkably. The bolt of tetraploid was later. The flow cytometry was used to identify the ploidy of induced-plants. The results suggested that the relative DNA content of CK was 100,and the tetraploidy relative DNA content was 200.There were two peak in one plant and the ratio were 1 and 2 with CK indicating chimeras(4x+2x).The identified result of flow cytometry was accord with that of chromosome analysis,implied the flow cytometry could identify the ploidy of non-heading Chinese cabbage accurately.2. The changes of soluble sugar,soluble protein,malondialdehyde(MDA), proline, superoxide dismutase (SOD), peroxidase (POD) catalase(CAT) and leakage rate of elctrolyte in leaves of diploidy and tetraploidy non-heading Chinese cabbage plants under cold stress were studied. Under the cold stress, the content of malondialdehyde (MDA) and praline were changed both in 2x and 4x non-heading Chinese cabbage, although the content of 4x non-heading Chinese cabbage was lower than that of 2x one. soluble sugar and the leakage rate of elctrolyte were similar to that of 2x one. the activity of superoxide dismutase (SOD) , peroxidase (POD) and catalase(CAT), the content of soluble protein and soluble protein in 4x non-heading Chinese cabbage were all higher than those in 2x one. The result suggest that cold-tolerance of tetraploidy non-heading Chinese cabbage is better than that of diploidy non-heading Chinese cabbage.3. Variability of superoxide dismutase ( SOD), peroxidase (POD) and esterase (EST) isoenzymes of diploid and autotetraploid non-heading Chinese cabbage were studied with polyacrylamide gel eletrophoresis. The results indicated that esterase (EST) isoenzyme bands of autotetraploidy non-heading Chinese cabbage were one or two more than those of the diploid both in the nutritional growing stage and florescence; the number of peroxidase (POD) isoenzyme bands of autotetraploid was the same to that of the diploid, but the color was darker, the difference was significant; superoxide dismutase (SOD) isoenzyme bands of autotetraploid and diploid were same in nutritional growing stage, but the activity was stronger than that of the diploid in florescence.4.Analysis of agronomic and nutritional trait on diploidy and tetraploidy non-heading Chinese cabbage. The results show that plant height,leaves number and plant width are reduced. And leaves width, plant width are increase and leaves shape is roundness. Petiole length is reduce,but width and thickness are increase. Leaves weight of per plant and the ratio of leaves and petiole are increase. The differences of soluable sugar ,soluable protein,Vc, organic acid,dried material and cellulose in diploidy and tetraploidy non-heading Chinese cabbage.