| Cut flowers play a very important role in the production of world flowers. As cut flowers are fresh horticulture products, they have life activities after harvest, and the investigation has been received too much ateention on physiology and biochemistry of cut flower and preservation after harvest become a more active garden area. Atmospheric CO2 concentration has inceased about 100μmol·mol-1 over the past 200 years. As an important raw material of photosynthesis, the rising of CO2 concentration will have a direct impact on the photosynthesis of cut flower, which may indirectly affect cell physiology and biochemistry of cut flowers. In addition, elevated CO2 can also reduce plant respiration, thus may also inhibit respiration to extend their vase life. Currently, elevated CO2 have a positive impact on plant growth and development, whether elevated CO2 have positive impact on postharvest preservation of cut flower is a ploblem to be solved for our stuty. In addition, if elevated CO2 have positive impact on cut flower, then study and explore the impact mechanism is another problem to be sloved for our study. So using physiological and biochemical and cell biology methods, we researched the influence of elevated CO2 on ornamental quality, physiological and structural characteristics of cut chrysanthemum and cut rose in order to provide a theoretical basis for the preservation of cut chrysanthemum, cut rose and even other type of cut flowers in elevated CO2.Lotus (Nelumbo nucifera) is a perennial water flower and native to China and it is one of the top ten traditional flowers of China. Hybrid seed set of different hybrid combinations have a very difference in lotus cross breeding, but the specific factors is unclear. Hybrid seed set is closely related to characteristics of plant reproductive biology, there is little reseach on reproductive biology on lotus and reports of the mechanism of hybrid reproductive barriers of lotus is now unavailable. In the present study, we selected six lotus species and designed six crosses, i.e. N.nucifera'Guili'x N.nucifera'Aijiangnan',N.nucifera 'Aijiangnan' x N.nucifera'Guili',N.nucifera 'Molingqiuse' x N.nucifera 'Qinhuaiyanzhi',N.nucifera'Qinhuaiyanzhi'x N.nucifera'Molingqiuse',N.nucifera 'Jinsenianhua'x N.nucifera'Qinhuaihuadeng' and N.nucifera'Qinhuaihuadeng' x N.nucifera'Jinsenianhua'. In order to reveal the hybrid reproductive barriers of lotus and provide theoretical basis to improve hybrid effect of lotus, we used means of cell and reproductive biology at various times after artificial hybridization, and studied the types and developmental stages of reproductive barriers affecting hybrid seed set.The main results and conclusions are listed as follows:1. Elevated CO2 increased fresh weight and flower diameter of cut chrysanthemum, retarded its senescence, and extended its vase life. In addition, elevated CO2 enhanced photosynthetic rate, contents of chlorophyll and soluble sugar, and activities of superoxide dismutase (SOD) and peroxidase (POD), but reduced malondialdehyde (MDA) content. Furthermore, elevated CO? retarded cell degeneration in leaves and petals. We have the conclusion that it is possible that elevated CO2 first provided more carbohydrates for normal cell metabolism of cut flowers through directly increasing photosynthetic rate, and indirectly retarded cell degeneration by enhancing activities of SOD and POD. As a consequence, elevated CO2 extended life of cut flowers.2. Elevated CO2 increased fresh weight and flower diameter of cut rose, retarded its senescence, and extended its vase life. Elevated CO2 enhanced photosynthetic rate, and activities of superoxide dismutase (SOD) and peroxidase (POD), but reduced malondialdehyde (MDA) content. Result:Elevated CO2 treatment extended vase life of cut rose, improve the vase quality and ornamental of cut rose.3. In order to study the reasons affecting seed set of interspecific hybridization for lotus, we chosed six varieties to conduct hybridization. We determined the pollen viability, observed the phenomenon of pollen germination on stigma and studied the embryo development. The results showed that pollen grains collected at 5:00-6:00 had the highest viability. The pollen viabilities of six lotus species at this time were 20.2±1.1% for N.nucifera 'Aijiangnan',16.2±1.2% for N.nucifera 'Guili',15.5±1.6% for N.nucifera 'Qinhuaiyanzhi',11.9±2.1% for N.nucifera 'Molingqiuse',20.6±1.3% for N.nucifera 'Jinsenianhua' and 15.7±2.0% for N.nucifera 'Qinhuaihuadeng' respectively. At 4 h after artificial pollination, the number of pollen grains germinating on each stigma reached the peak, the numbers are 60.6 for 'Guili' x 'Aijiangnan',25.8 for 'Aijiangnan' x 'Guili',4.8 for 'Qinhuaiyanzhi'×'Molingqiuse',10.0 for 'Molingqiuse'×'Qinhuaiyanzhi',17.2 for'Qinhuaihuadeng'×'Jinsenianhua' and 63.0 for 'Jinsenianhua'×'Qinhuaihuadeng'. In 'Qinhuaiyanzhi'×'Molingqiuse' and 'Molingqiuse'×'Qinhuaiyanzhi', there were very little pollen grains germinated on the sigma after pollination, and basically all the pollen tubes of germinating pollen grains appeared abnormal, and stayed on the stigma diffcult to ovary. At 1 day after pollination, the proportion of normal embryos of the six combinations were 58.8%,26.8%,7.6%, 9.6%,21.9% and 55.0%, respectively. At 11 days after pollination, the proportion of normal embryos of the six combinations were 25.0%,11.3%,0%,1.5%,11.2% and 20.8%, respectively. Afterwars, the proportion of normal embryos changed little. The final seed set of the six crosses were 23.33%,9.24%,0.23%,3.11%,8.02% and 17.90%, respectively. The seed set of the six maternal plants under open pollination conditions were 26.5%,34.9%,8.39%,11.5%,29.4% and 41.6%, respectively. All these data suggest that pollen viability of male parents had no significant effects on seed set of the six crosses. The germinating behavior of pollen grains on stigmas was a main factor reducing seed set. Embryo abortion also was a very important factor resuling in low seed set. |
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