Abstract:

To obtain the high-yield and high-quality non-heading Chinese cabbage autotetraploid Suzhouqing, in this study, cotyledon growth points of diploid Suzhouqing seedling plants were treated using colchicines solution with concentration of 0.1%, 0.2%, and 0.3%, respectively. After five treatments, tetraploid Suzhouqing plants were screened and identified by morphological and cytological methods. The agronomic characters and quality difference were compared between diploid and tetraploid Suzhouqing. The results showed that the doubling effect of Suzhouqing was the best when the concentration of colchicine was 0.2%. According to morphological anatomy, the tetraploid plant type, leaf, flower, seed pod and seed size all had an obvious trend of increasing. Tetraploid plant leaves had larger stomata size and smaller stomatal density than diploids. And the pollen grain of tetraploid plants was larger and more irregular than that of diploids. Cytologic results showed that there were 40 chromosomes in tetraploid plants and 20 chromosomes in diploid plants. Flow cytometry analysis indicated that tetraploid plants had about twice the fluorescence intensity of diploid. The results showed that the contents of physiological indexes of tetraploid Suzhouqing were different from those of diploid through quality comparison and analysis. Through the comparison of agronomic characters, the average individual mass, leaf width and leaf thickness all increased to a certain extent. In this study, colchicine was used to inhibit the formation of spindles at mitotic anaphase and to achieve chromosome doubling. A new germplasm of non-heading Chinese cabbage was created to provide a theoretical basis and germplasm resources for breeding new tetraploid non- heading Chinese cabbage.

Key words: non-heading Chinese cabbage, colchicine, autotetraploid, Suzhouqing, quality identification