Investigation On Mechanism Of Green Disk Florets Of Spray Cut Chrysanthemum

Chrysanthemum(Chrysanthemum morifolium) is one of the most important ornamentals. Chrysanthemum, especially spray cut Chrysanthemum, occupies an important position in the global cut flowers production because of its characteristics such as rich color and floral shape, more flowers, flowering uniformity and long flowering period. As the most angiosperms evolution of groups, analyzing the phenotypic traits of design and color will also provide resources for the research on evolutionary biology. At the same time, the research of design and color is formed for chrysanthemum varieties classification and lays a foundation in the cultivation of a new breed of design and color.This study chosed spray cut chrysanthemum with green-core ’Q11-34-1’ and spray cut chrysanthemum with yellow-core’QX-081’.The differences of morphological structure of disk florets in different flowering stages of’Q11-34-1’and’QX-081’were observed, using stereoscope and TEM technology. And the differences of physiological aspects of disk florets in different flowering stages of ’Q11-34-1’ and ’QX-081’ were observed by measuring content of some common pigments and endogenous hormones. The main results and conclusions are listed as follows:(1) Flowering period of ’Q11-34-1’ is 24.0 days. And flowering period of’QX-081’ is 17.0days. The former is 1.41 times as long as the latter. Number of disk florets per inflorescence of ’Q11-34-1’ is 155.6. And number of disk florets per inflorescence of ’QX-081’is 132. Postures microscope was used to observe the disk florets of ’Q11-34-1’ and ’QX-081’ during period 3、4、5. Through this research, the flowering phase of Spray cut chrysanthemum is established preliminary, including 6 phases. Phase 1:Outer layer lingulate flowers begin to flower, namely, just flower bud. Phase 2:Outer layer lingulate flowers become vertical shape. Phase 3:Outer layer lingulate flowers are in full bloom. Phase 4:The outer disk floret gradually turn yellow. Phase 5:Disk floret 10～20% powder. Phase 6:Disk floret 80～90% powder. The results suggest that the flowering period of ’Q11-34-1’ is longer than ’QX-081’. And the color of spray cut chrysanthemum is mainly decided by color of disk floret corolla.(2) From flowering phase 1 to flowering phase 4, the number of chloroplasts per cell of ’Q11-34-1’is respectively 12.5.12.3.13.5.12.0. The number of chloroplasts per cell of ’QX-081’ is respectively 13.0.12.5.13.5.11.0. Chloroplast length of ’Q11-34-1’is respectively 31.6.36.8.34.3.37.2 μm. Chloroplast width of ’Q11-34-1’ is respectively 14.5.15.4.14.6.15.8 μm; However, Chloroplast length of’QX-081’is respectively 26.0. 24.6.29.3.31.6 μm. Chloroplast width of’QX-081’is respectively 15.2.16.7.18.4.17.0 μm. Number of grana thylakoid membranes of ’Q11-34-1’ is respectively 5.3、5.8、5.3、 4.8.Number of grana thylakoid membranes of’QX-081’is respectively 5.0.5.5.5.3.5.0. Number of starch grains per chloroplast profile of ’Q11-34-1’ is respectively 2.8、4.3. 5.0、5.5. Number of starch grains per chloroplast profile of’QX-081’is respectively 3.0. 4.0、4.8、5.0. The research suggests that from flowering phase 1 to flowering phase 4,the number of chloroplasts per cell, Chloroplast length, Chloroplast width, number of grana thylakoid membranes don’t change obviously, but the number of starch grains per chloroplast profile increase gradually. Among them, the shape of chloroplast of ’Q11-34-1’ is almost fusiform, but the shape of chloroplast of ’QX-081’ is almost round. The chloroplast of ’Q11-34-1’ is larger than the chloroplast of ’QX-081’. Thylakoid membrane structure of chloroplasts of ’Q11-34-1’ looks more clear than ’QX-081’. The results suggest that the color of spray cut chrysanthemum is decisded by the size of the chloroplast and the definition of grana thylakoid membranes structure.(3) The content of flower pigments such as chlorophyll, carotenoids, anthocyanins and flavonoids of tubular flowers of ’Q11-34-1’ and ’QX-081’ was measured. The content of Chlorophyll, carotenoid, anthocyanin is very low, however the content of flavonoids is relatively higher. From flowering phase 1 to flowering phase 5, the Content of chlorophyll of ’Q11-34-1’ disk floret is respectively 0.128、0.132、0.1225、0.11、0.086 mg/g. The Content of chlorophyll of’QX-081’disk floret is respectively 0.088.0.088.0.077.0.072. 0.067 mg/g; The content of carotenoid of ’Q11-34-1’ disk floret is respectively 0.019. 0.026.0.059.0.065.0.073 mg/g. The content of carotenoid of’QX-081’disk floret is respectively 0.083.0.094.0.103.0.110.0.123 mg/g; The content of chlorophyll/Content of carotenoid of ’Q11-34-1’is respectively 6.716.5.06.2.066.1.683.1.181. The content of chlorophyll/Content of carotenoid of’QX-081’is respectively 1.012.0.94.0.746. 0.653.0.544; Unit of anthocyanin of ’Q11-34-1’ is respectively 0.076.0.070.0.068.0.065. 0.061 A (one unit/A=1). Unit of anthocyanin of’QX-081’is respectively 0.07.0.067. 0.063.0.061.0.0570 A (one unit/A=1). Yield of flavonoids of ’Q11-34-1’ disk floret is respectively 13.810.17.951.15.012.13.454.9.802 mg/g. Yield of flavonoids of ’QX-081’disk floret is respectively 14.300.16.526.15.636.13.142.11.450 mg/g. The research suggests that from flowering phase 1 to flowering phase 5,the Content of chlorophyll in disk florets of ’Q11-34-1’ and ’QX-081’ first rises then falls; the content of carotenoids continues to decline; the content of anthocyanins continues to decline; the Content of flavonoid first rises then falls; the ratio of Content of chlorophyll/content of carotenoids first rises then falls. The ratios of ’Q11-34-1’are>l,but the ratios of’QX-081’is >1 in flowering phase 1,and if the ratioof content of chlorophyll/content of carotenoids is>l,the proportion of disk florets in inflorescence which show green is more than the proportion which show yellow. if the ratioof content of chlorophyll/content of carotenoids <1, the proportion of disk florets in inflorescence which show green is less than the proportion which show yellow.And disk florets present green when content of chlorophyll in Chloroplasts is more higher than content of carotenoid in chloroplasts. The results show that the color of disk florets is mainly determinded by the proportion of content of chlorophyll and carotenoids in its shells.(4)From flowering phase 1 to flowering phase 4, the content of IAA in disk florets of ’Q11-34-1’ is respectively 1892.7,1073.7,413.7,232.7 ng·g-1 FW,and the content of IAA in disk florets of’QX-081’is respectively 3421.0,693.3,356.7,253.7 ng·g-1 FW;the content of ABA in disk florets of ’Q11-34-1’ is respectively 1004.0,193.0,68.3,188.7 ng·g-1 FW,and the content of ABA in disk florets of’QX-081’is respectively 1761.0, 167.0,45.7,116.0 ng-g’1 FW. The research suggests that from flowering phase 1 to flowering phase 5, the content of IAA in disk florets of ’Q11-34-1’ and ’QX-081’ fcontinues to decline, the content of ABA in disk florets of ’Q11-34-1’ and ’QX-081’ first falls then rises.The results show that flower colour of spray cut chrysanthemum is effected by inflorescence development which is regulated by the content of IAA and ABA.(5) Spraying IAA,6-BA and SA to the disk florets of ’Q11-34-1’ and ’QX-081’ in flowering phase 3. The research suggests that,0.1 mg/L 6-BA is found to be able to furthest extend flowering phase of ’Q11-34-1’ and ’QX-081’,and extends 2.2 and 0.7 days respectively;0.1 mg/L IAA is found to be able to furthest extend flowering phase of ’Q11-34-1’ and ’QX-081’,and extends 1.0 and 0.3 days respectively; 10 mg/L SA is found to be able to furthest extend flowering phase of ’Q11-34-1’ and ’QX-081’,and extends 1.0 and 0.7 days respectively.The results show that flowering phase of spray cut chrysanthemum is effected by IAA、ABA and SA. The results show that IAA、6-BA、SA are found to be able to extend flowering phase of spray cut chrysanthemum.And treatment effect for ’Q11-34-1’ is better than treatment effect for’QX-081’.treatment effect of 6-BA is the best among three hormones.