Mechanism Of Floral Formation Of Cymbidium Kanran And Flowering Regulation

Cymbidium kanran, one of historically famous and beloved Chinese ornamental plants, has great ornamental and economic value. Its natural florescence is October to December, which does not overlap with many important Chinese festivals or holidays, such as Chinese New Years and Spring Festival. As a result, its absence is notable in the holiday market and hinders the growth and development of the C. kanran industry. Furthermore, the mechanism for flower bud differentiation is still controversial. Research on the mechanism of floral formation and flowering regulation can promote the expansion and development of the C. kanran industry. This research studied the development in morphology and structure during C. kanran flower differentiation using manual dissection and paraffin section, and documented the observed physiological changes. The effects of varying temperatures, photoperiods, hormones, and NPK ratios on bloom and flower quality were also studied. Through this research, key findings were captured and were summarized below:1 Typical flower differentiation could be divided into six phases:1) undifferentiation,2) flower primordium differentiation,3) inflorescence primordium differentiation,4) petal differentiation,5) column differentiation, and 6) flower consummation. The differentiation and development of the flower labellum could be divided into a separate set of three phrases-labellum differentiation, lamella emergence, and tinging-and occured during the later differentiation phases of petal differentiation, column differentiation, and flower consummation. Similarly, the differentiation and development of the flower column could be divided into five phases-stamen differentiation, rostellum emergence, pistil differentiation, column formation and tinting-that occured during column differentiation and flower consummation.2 In the five stages from flower bud differentiation to bloom (1) inflorescence primordium differentiation,2) column differentiation,3) the small bell,4) the big bell, and 5) flowering time), soluble protein levels remained stable in both pseudobulbs and leaves. In pseudobulbs, soluble sugar and starch levels showed a trend of first decrease and then increase. While sucrose levels were observed to first increase then decrease and then increase. Over the entire five stages, the soluble sugar and sucrose levels in leaves were observed to decrease and then increase with the exactly same accordence. Simultaneously, starch levels were observed to increase, then decrease, and finally increase again. Furthermore, the ratios of sucrose to soluble sugar in pseudobulbs and leaves showed little correlation.In pseudobulbs, GA3 and ABA remained stable. While low levels of ZR and IAA promoted flower differentiation, high levels of ZR and IAA promoted flower development. Ratios of ZR to IAA, ABA to IAA and ZR to GA3 remained stable. High ratios of ABA to GA3 in pseudobulbs promoted flower differentiation, while low ratios of them promoted flower development. During flower differentiation, the content of ZR was significantly correlated with GA3 and IAA (within five percent), and was highly significantly correlated with ABA (within one percent); the content of GA3 was also significantly correlated with ABA (within five percent); and the content of IAA and ABA was significant correlated in pseudobulbs (within five percent). All hormones showed positive correlation. In leaves, the content of GA3 remained stable. High levels of ZR, high ratios of ZR to IAA and ZR to GA3 promoted flower differentiation, low levels of ZR, low ratios of ZR to IAA and ZR to GA3 promoted flower development. There was no significant correlation between the four endogenous hormones in leaves.3 When temperature regulation was used, plants maintained in 30/16℃ (day/night) for 45 days bloomed early, and this treatment did not have adverse effect on flower quality. Plants treated with eight hours of light daily, bloomed early. When plants were treated with N:P:K=9:45:15, SA 50 mg·L-1,6-BA 50 mg·L-1, time to anthesis was postponed, while little damage was oberved to the flower quality.This thesis documents the structural development and physiological changes of the Cymbidium kanran during flower differentiation, with particular focus on the the development of flower labellum and flower column. Furthermore, it describes the levels of proteins, carbohydrate, hormones observed in the plant during the flower differentiation phases. Finally, this thesis summarizes that cold treatment and shorten illumination time can advance time to anthesis, while the optimum matching of NPK and hormones can postpone flower fime.