Optimization Of In Vivo Bud Regeneration Technique Via Callus And Its Application In Polyploidy Induction In Chinese Jujube And Sour Jujube

In this study, total 116 Chinese jujube and 3 sour jujube genotypes were employed to optimize the in vivo bud regeneration technique via callus by studying the relative factors in bud regeneration and effect of colchicine application times on polyploidy induction.The optimized in vivo bud regeneration technique was employed in polyploid induction in Chinese jujube(Ziziphus jujuba Mill.)and sour jujube(Z. acidojujuba C. Y. Cheng et M. J. Liu) genotypes and 9 polyploids were acquired. The main results were as follows:1. Genotypes significantly influenced callus induction. Among the 119 genotypes,94.96% could produce callus in different degree and therefore the tested genotypes were classified into 5 groups. Group A, B, C, D and E with callus ratio of 75%-100%,50%-75%, 25%-50%, 0-25% and 0, accounted for 56.30%, 24.37%, 10.92%, 3.36% and5.05% of the tested genotypes respectively.2. The effect of genotype on bud regeneration ability was also studied and the tested genotypes were divided into 5 groups according to bud regeneration ability. Group I, II,III, Ⅳ and Ⅴ with average bud number per cross section of >3.0, 2.0-3.0, 1.0-2.0,0-1.0and 0, accounted for 20.17%, 10.08%, 16.81%, 33.61% and 19.33% of the tested genotypes respectively.3. The results showed that there was no significant correlation between average bud No. per cross section and callus ratio. It’s also found that the callus quantity influenced the bed regeneration ability to some degree and with the increase of callus quantity,average bud No. per cross section increased and topped 2.86 when the callus grade was 5.Then, bud regeneration ability slightly decreased on callus in grade 6 of which the width of the callus circle accounts for over 1/2 of the cut section’s radius.4. The results showed that branch diameter somewhat influenced bud regeneration and the branches with diameter of 1.4-1.9cm cloud relative easier to regenerate buds by showing that 30 d after branch were cut, the average bud number per cut section could reach 2, which is significantly higher than those of branches of 0.9-1.4cm and 1.9-2.4cm.The upright branches in the up part of the canopy showed higher bud regeneration abilitythan those in the mid or lower part while branches at different horizontal location and angle showed no significant difference in bud regeneration.5. The effect of colchicine application times on polyploid induction was finally studied. Callus ratio, average bud number per cross section and induced mutation ratio decreased by 24.01%, 1.61% and 2.52% respectively in twice colchicine application compared to once 0.05% colchicine application.6.The in vivo callus buds regeneration system was optimized and its procedure was as follows: In the mid or late May, erect branches with diameter of 1.4-1.9cm in the uppart of canopy was cut and 1.5ml inducing agent including 4.0mg · L-1 TDZ and2.0mg·L-1 Ag NO3 was applied on the cambium of the cut section and kept for 24 h. The cambium of the cut section was then covered with mud to keep moisture inside until the regenerated bud reach 2cm in length.7. Totally 9 polyploid germplasms were obtained, of which 3 were tetraploid i.e.‘Lejin 1’, ‘Yunchengpopozao’ and ‘Nixiachangzao’, 2 were triploid i.e. ‘Junzao’ and‘Mopanzao’ and 4 were mixoploid, including ‘Chahuzao’, ‘Junzao’, ‘Taigulinglingzao’and ‘Hongzhaoxiaozao’.