A Study On Induction, Identification And Cytoembryology Of Autotetraploid In Head Cabbage Self-incompatibility Lines

Two diploid head cabbage self-incompatibility lines were used to induce autotetraploid by artificial inducing technique, and the meiosis behaviors, embryo development, self-compatibility and some other biological characters of the tetraploid were studied in this paper. The main results were showed as follows:l.The optimum colchicine concentration and duration of inducing treatment were 0.2% and 64 hours respectively. Under this condition, treating the optical potion of seedlings, the average variation rate was 34.35%.2.The obtained tetraploid head cabbage showed the general characters of polyploid plant, such as, the leave becoming thicker, leaf type index becoming smaller, buds and petals becoming larger, stomata density of leaf endocuticle reduced, and the number of chloroplast in per guard cell increased.3.The meiosis behavior of the induced tetraploid head cabbage was much more complex than that of the diploid. Such as, at diakinesis, besides divalent and quadrivalent, some trivalent and univalent were also observed. In the different pollen mother cells, the type of chromosome patings varied from 9 quadrivalents to 18 divalents, the dissociate chromosomes existed during metaphase I and metaphase II, the laggard chromosomes and unbalant separation of chromosomes existed during anaphase I and anaphase II.4.The progress of pollination, fertilization and embryo development in tetraploid head cabbage was similar to that in diploid head cabbage. But the stages of embryo development was late about 2d~3d, and the endosperm was without obviously cell formation stage in the tetraploid. Besides, the rate of fertilized embryo sac in the tetraploid was lower than that of in the diploid.5.1n comparison with the diploid self-incompatibility parents, the self-incompatibility of the induced tetraploid head cabbage has not taken place the nature change, that is, it has still maintained the genetic character of the self-incompatibility.6.The seed setting of head cabbage self-incompatibility lines can be improved by repeated pollination or treated ovary with GAi and NAA. for example, by 3 times pollination at bud stage or alternatively treated ovary 5 times with 50ppm GA3 and 300ppm NAA after pollination at flower stage, the self- compatibility coefficient was increased 118.73% and 154.18% respectively than that of CK in the tetraploid head cabbage.