| The study content of this paper is divided into two parts. First, study on the photosynthetic characteristics of different Chrysanthemum varieties: taking 10 Chrysanthemum varieties as materials, this experiment comparatively studied the photosynthetic characteristics of different Chrysanthemum varieties using portable CIRAS-2 photosynthetic system, revealed their photosynthetic physiology characters, analyzed the relationship between photosynthetic physiology characters difference and environmental factors, made clear the basic law of their photosynthesis, providing the technical support for the cultivating administration and reasonable distribution of Chrysanthemum in landscape application. Second, study on salt resistance: in this experiment, 4 Chrysanthemum varieties were treated with salt stress of different degrees by pot experiment, changes of photosynthetic and related physiological characteristics of different Chrysanthemum varieties were determined, the anti-salt ability and mechanism on salt resistance of them were studied. It intends to provid theory basis for the cultivation, breeding, and landscape application of salt-tolerance of Chrysanthemum varieties.㈠Study on the photosynthetic characteristics1. Characteristics change of light and CO2 response curves: the LSP of th-e10 Chrysanthemum varieties was 962~1078μmol m-2·s-1; LCP was 92.9~167.4μmol·m-2·s-1; CCP was 77.8~133.2μmol·mol-1; CSP was 1062~1487μmol·mol-1. The above results show that Chrysanthemum is photophilous, requiring adequatesunlight, is a typical C3 plant. The LSP and LCP of 'Zaofenpan' and 'Tanxiangs-hizi' were higher; 'Taipingxiaogu' had higher LSP and lower LCP; 'Richudongf-ang', 'Guandongxinxia', 'Lvmudan' and 'Xingguangcanlan' had higher LCP and lower LSP; the LSP and LCP of 'Ribenhuang' and 'Yunlongfengwu' were lower.When CO2 concentration was under 500μmol·mol-1, Pn of 10 Chrysanthemum varieties increased with the increasing of CO2 concentration; CO2 concentration was 300~800μmol·mol-1, Pn value 6.75~24.4μmol·m-2·s-1. So the increasing of CO2 concentration improves the Pn of Chrysanthemum significantly. 2. The Pn diurnal variation of 10 Chrysanthemum varieties presented a typ-ical bimodal curve, the first peak was in 10:00 with a peak value of 11~19μmol·m-2·s-1, and the second was around 16:00 with a peak value of 4.7~7.95μmol·m-2·s-1; the photosynthesis had a significant midday depression phenomeno-n. Diurnal variations of Gs and Tr were similar to that of Pn, appearing as the bimodal curve; peaks of Gs and Tr were around 10:00 and 12:00 respectiv-ely, and the second peak appeared around 16:00; troughs of them were around14:00. Diurnal variation trend of Ci was opposite to that of Pn, around 6:00, 14:00 and 18:00, Ci was higher, and the lowest value appeared around 10:00 and 16:00.3. 'Zaofenpan' and 'Tanxiangshizi' had stronger sunshine-tolerant; 'Ribenhua-ng' and 'Yunlongfengwu' had strongest sunshine-tolerant; 'Tipingxiaogu' and 'Ton-gquechentan' had strong adaptability to the lighting conditions; the range of ill-umination intensity could be exploited by 'Richudongfang', 'Guandongxinxia', 'Lvmudan' and 'Xingguangcanlan' was smaller. Diurnal variation of 10 Chrysant-hemum varieties was typical bimodal curve, and there's a significant photosynt-hesis midday depression phenomenon. The photosynthesis of Chrysanthemum le-aves is affected by the physiological and ecological factors of Gs, Ci, Tr, PAR, etc. In the production practice, treating Chrysanthemum with shade condit-ion and sprinkler irrigation in the high temperature and low humidity summer could decrease Ta, increase RH, reduce midday depression phenomenon and improve its photosynthesis production capability.㈡Study on salt resistance1. With the increasing of NaCl stress degree, the relative electric conducti-vity of 4 Chrysanthemum varieties presented the rising trend; MDA content var-ied subtly under low concentration, but increased under high concentration. Th-e injured degrees of different varieties were different. Under lower NaCl conc-entration, the electric conductivity and MDA content of 'Guandongxinxia' variedsignificantly; under higher NaCl concentration, those of 'Richudongfang' and 'Yunlongfengwu' rose rapidly, and the increasing range of 'Yunlongfengwu' was larger; through the whole stress process, those of 'Zaofenpan' presented a smallincreasing range, which were the lowest.2. Under higher NaCl concentration, Pro, SS and SP contents of 4 Chrysa-nthemum varieties increased. when NaCl concentration was 0.4%, Pro content of 'Guandongxinxia' rose rapidly; NaCl concentration 0.6%, Pro, SS and SP contents of 'Richudongfang' and 'Yunlongfengwu' rose rapidly, and the increasin-g range of 'Yunlongfengwu' was larger; NaCl concentration 0.8%, Pro, SS andSP contents of 'Zaofenpan' and SS and SP contents of 'Richudongfang' rose ra-pidly, and soluble protein in 'Zaofenpan' compounded rapidly, meanwhile, SP content of 'Guandongxinxia' decreased, probablely that's because the high salt concertraction stress was beyond the accommodative ability of 'Guandongxinxia'.It is clear that, under salt stress, SS and SP contents of Chrysanthemum leave-s rise greatly to maintain the osmotic equilibrium, reduce the cell's osmotic po-tential, protect the structure of membrane and enzyme, and relieve the stress.3. Through the stress process, the SOD and CAT activities of 'Zaofenpan', 'Richudongfang' and 'Yunlongfengwu' increased, the increasing range of 'Zaofenp-an' was larger than that of 'Richudongfang', which indicates that under high concentration salt stress, their protective enzyme play an important part in resis-ting NaCl stress, showing a strong salt-resistance ability. The SOD, POD and CAT activities decreased under high concentration salt stress, and the injure fro-m the stress exceeded its accommodative ability, the cytomembrane system wa-s destroyed seriously. Results show: salt stress injures 'Zaofenpan' slighest, 'Ric-hudongfang' and 'Yunlongfengwu' slighter, and 'Guandongxinxia' most heavily.4. With the increasing of NaCl stress degree, Chl content and Pn value ofChrysanthemum varieties increased slightly under lower concentration, and decr-eased significantly under higher concentration. High concentration salt stress made chlorophyll of Chrysanthemum leaves degraded, significantly inhibited thephotosynthesis of 4 Chrysanthemum varieties. 'Zaofenpan' was inhibited the lea-st, presenting the strongest salt-resistance, followed by 'Richudongfang' and 'Yunlongfengwu', and 'Guandongxinxia' was inhibited most seriously, presenting the weaker salt-resistance ability. High Chl content ensures the strong photosynt-hetic capability of 'Zaofenpan', which has the strongest salt-resistance.5. Under salt stress treatment, 4 Chrysanthemum varieties presented differe-nt response mechanism. Experiments show: the Pro accumulation of Chrysanth-emum is a physiological response to salt stress, but not a index of measuring the plant's salt-resistance ability. 'Zaofenpan' was insensitive to salt stress, the increasing range of proline content in leaf was small, the leaf had strong antio-xidative enzyme activity, cytomembrane was injured less, which kept the leaf's high Chl content and Pn, so the salt-resistance ability was the strongest. The order of the 4 tested Chrysanthemum varieties' salt-resistance was: 'Zaofenpan'>'Richudongfang'> 'Yunlongfengwu'> 'Guandongxinxia'.
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