Effects Of GA₃ And Photoperiod On Physiology And Flowering In Taraxacum Kok-saghyz Rodin

Taraxacum kok-saghyz Rodin (TKS) , as one of a important rubber producing crops emerging in recent years, with the advantages of high rubber content and high quality rubber, etc., was given widely attention in the world. Gibberellin and photoperiod, as important ways to regulate flowering, have been widely used in the regulation of flowering process. In this project, the effect of GA3 and photoperiod on physiology and flowering on TKS was analyzed, so as to explore the optimum treatment conditions, which would shorten the growth cycle and promote flowering.The knowledge gained would lay the foundation for propagation andgermplasm resource collection and conservation ofTKS. The main results are as follows.1. The effects of GA3 on squaring date, early flowering date, blooming date,ending flowering date, florescence, flower shape and Physiological indexes of TKS in seedling stage and florescence were analyzed. The results showed that, the content of chlorophyll, soluble protein content, soluble sugar content, starch content of leaves of the treatments with GA3 were lower than that of CK. After bud stage, the soluble protein content, soluble sugar content, starch content of leaves decreased after the peak and the decline degree was less than that of CK, the peak of GA3 treatments at the same time or delay than that of CK. The soluble sugar content/soluble protein content of leaves present an increasing trend and the value less than that of CK. It was implied that the application of GA3 could promote the flowering shape except flower number. In the flowering period, SOD, POD and CAT activity of leaves rise at first and then decrease, MDA content increase gradually. In every period of flowering,SOD, POD and CAT activity of leaves with GA3 treatment is lower than that of CK,MDA content is just the opposite. GA3 promoted the length of scape, the coarseness of scapes, flower diameter and single ligule floret number increases, reducing the number of buds per plant.Compared with CK, budding period and early flowering of TKS are delayed with GA3 treatment, and florescence shortened. Among them, the budding and flowering is latest under the treatment of GA3 is 150mg/L, and the florescence is shortest. In summary, GA3 reduced metabolites content, photosynthetic pigments content and antioxidant enzymes activities of TKS, and contributed to the membrane lipid peroxidation. It made a significant influence in the flowering phase and flowering shape.2. The effects of photoperiod on squaring date, early flowering date, blooming date, ending flowering date, florescence, flower shape and physiological indexes ofTKS in florescence were analyzed. The results showed that, in the flowering period,soluble protein content, soluble sugar content and starch content of leaves rise at first and then dropped, the peak appears at the early flowering stage. Long days condition can increased the soluble protein content, soluble sugar content and starch content of leaves,the longer the illumination time increased, the more obvious of increase.When photoperiod is between 8h to 18h, extending photoperiod made the budding of TKS in advance, the squaring stage to the early flowering stage and the early flowering stage to the blooming stage become shorter, prolonged the florescence. In addition, the coarseness of scapes, flower diameter, flower numbers and single lingulate flowers were observed increasingly with the increasing photoperiod. But for the length of scapes, there was no significant different among each treatment.Among them, in the flowering period, under 18h photoperiod (T6) treatment, the soluble protein content, the soluble sugar content and the starch content of leaves are the highest, flowering is the earliest, flower numbers are the most among all treatment.And there was a opposite result under 8h photoperiod (T1) treatment.