Effects Of CO₂ Enrichment On Growth And Leaf Structure Of 5 Chrysanthemum Cultivars

Studies on growth and leaf structure of 5 Chrysanthemum cultivars（‘Jinma’、‘Huangxiufeng’、edible Chrysanthemum、‘Qingxinbai’ and‘Fenhe’） under the CO₂ enrichment. This research used independent plastic tent, treated with rich CO₂:360μmol mol-1（CK）、700μmol mol-1（T1） and 1000μmol mol-1（T2） at 9:30-16:30 e veryday.The main results were as follows:Photoresponse:Pn, Gs and Tr of Chrysanthemum ‘Huangxiufeng’ and ‘Jinma’were higher initially then become stable and finally decrease as the light intensity i ncrease. The Pn of 2 cultivars were highly consistent with Gs and Tr, while negativ ely related to Ci. Chrysanthemum ‘Jinma’ and ‘Huangxiufeng’ had a narrow suitable light intensity scale and were shade resistant neither nor light resistant. CO₂ respon se: Pn, WUE and Ci of 2 cultivars were significantly enhanced as the CO₂ concent ration increase, photosynthesis rate enhanced. Gs and Tr were lower initially then b egin to rise as the CO₂ concentration increase.The height, leaf number and fresh weight of plants under CO₂ enrichment were significantly higher than those growing under ambient. The Plant of Chrysanthemum‘Huangxiufeng’, ‘Fenhe’ and edible Chrysanthemum in T2 environment grew bette r than that in T1 environment. But the plant of Chrysanthemum ‘Qingxinbai’ occur red reverse trends.The growth of Chrysanthemum ‘Jinma’ in T1 and T2 environment was no significant difference.After 30 d vegetative growth, Chrysanthemum ‘Jinma’, ‘Huangxiufeng’ and ‘Fen he’ soluble sugar content in leaves increased, soluble sugar content in leaves of edi ble Chrysanthemum and Chrysanthemum ‘Qingxinbai’ decreased. Soluble protein co ntent in leaves of five kinds of chrysanthemum were significantly increased. CO₂ e nrichment resulted in the larger accumulation of soluble sugar and protein in leaves of 5 Chrysanthemum cultivars. But the change of soluble sugar and soluble protein content of each type is different,soluble sugar and soluble protein content of Chry santhemum ‘Jinma’ in T2 environment increase more than that in T1 environment. t he content of Chrysanthemum ‘Huangxiufeng’ occurred reverse trends. The soluble sugar and soluble protein content of edible Chrysanthemum in T1 and T2 environm ent was no significant difference.The Chla/Chlb in leaves of Chrysanthemum ‘Jinma’, ‘Huangxiufeng’, ‘Fenhe’ an d edible Chrysanthemum reduced evidently under CO₂ enrichment, Shows that the P lant improve the ability of absorption, use of weak light. Chla in leaves increased of Chrysanthemum ‘Jinma’ under the CO₂ enrichment, but the plant of Chrysanthemu m ‘Qingxinbai’ and edible Chrysanthemum occurred reverse trends.The thickness of main leaf vein of 5 Chrysanthemum cultivars, the order from big to small is: Chrysanthemum ‘Huangxiufeng’, ‘Fenhe’, ‘Qingxinbai’, edible c hrysanthemum and ‘Jinma’. The thickness of main leaf vein of plants under CO₂ enr ichment were significantly thicker than those growing under ambient. In T2 environ ment, the thickness of main leaf vein grew thicker than that in T1 environment. The thickness of blade of 4 cut Chrysanthemum cultivars had no obvious changed unde r CO₂ enrichment, but The thickness of of blade of edible Chrysanthemum under C O2 enrichment were significantly thicker than those growing under ambient.The stomatal density and hair density of leaf inferior epidermis of 5 Chrysanth emum cultivars, the order from big to small is: Chrysanthemum ‘Qingxinbai’, ‘Hua ngxiufeng’, edible chrysanthemum, ‘Jinma’ and ‘Fenhe’.Stomatal appeared in leaf upper epidermis of Chrysanthemum ‘Jinma’, ‘Huangxi ufeng’ and ‘Fenhe’ under CO₂ enrichment. Stomatal area, stomatal density and hair density in leaf lower epidermis of plants under CO₂ enrichment were significantly gr eater than those growing under ambient.