Interactive Effects Of CO₂ Concentrati On And Temperature On Physiological Par Ameters Of Saussurea Kansuensis Hand.-Mazz

Under the environment background of the continued global warming, the elevated CO₂ concentration and increasing temperature are increasingly concerned by all over the world, and the documents about the effects of elevated CO₂ concentration and increasing temperature of plants are gradually increasing.There are studies of the effects of elevated CO₂ concentration and increasing temperature on photosynthetic parameters of plants. There are also many research on physiological indicators response of elevated CO₂ concentration and increasing temperature. People have researched the regulation of gene under the effect of CO₂ concentration and temperature from molecular level. Although related research documents are gradually increasing, there is little study about the physiological parameters of Saussurea kansuensis Hand.-Mazz under interaction of atmospheric CO₂ concentration and temperature. Saussurea kansuensis Hand.-Mazz, as a kind of the genus Saussurea of Asteraceae, is an endemic species in the eastern of Qinghai-Tibet Plateau. Our objective was to research the effects of elevated CO₂ concentration and increasing temperature on physiological parameters of S. kansuensis by using CO₂ artificial climate box?PRX-250C-CO₂, Shang Hai?.The research could help us to understand the physiological parameters of alpine meadow, and provide some basis for evaluating the global climate change effect on the ecosystem of alpine meadow and the restoration of degraded grassland.By using CO₂ artificial climate box, CO₂ concentration and temperature were simulated to 8 treatments?CckT0?CK,environment temperature?11 ???,CckT+2??CK,+ 2 ? ± 0.48 ??,C450T0?450 ?mol·mol-1,environment temperature?11 ???,C450T+2??450 ?mol·mol-1,+ 2 ? ± 0.48 ??,C550T0?550 ?mol·mol-1,environment temperature?11 ???,C550T+2??550 ?mol·mol-1,+ 2 ? ± 0.48 ??,C650T0?650 ?mol·mol-1,environment temperature?11 ???,C650T+2??650 ?mol·mol-1, + 2 ? ± 0.48 ???. CckT0 was control group. The results showed:?1? Under the interaction of atmospheric CO₂ concentration and temperature, the germination rate and germination index of S. kansuensis seeds were significantly increased. If CO₂ concentration and temperature were more than the germinal critical value of S. kansuensis seeds, the germination rate and germination index would be decreased. The germination index and germination rate of S. kansuensis seeds increased continuously at the 2 ? ± 0.48 ?.?2? The chlorophyll a, chlorophyll b and carotenoid content in leaf of S. kansuensis increased greatly under interaction of atmospheric CO₂ concentration and temperature. The chlorophyll a, chlorophyll b and carotenoid content increased under higher CO₂ concentration, while their contents were decreasing when the CO₂ concentration was over 550 ?mol·mol-1. At CO₂ concentration of 550 ?mol·mol-1, elevated temperature could significantly enhance the amount of chlorophyll a, chlorophyll b and carotenoid.?3? With the increasing CO₂ concentration, MDA, relative conductivity, superoxide anion and proline content in leaf of S. kansuensis decreased under the same temperature. When the temperature was higher, MDA, relative conductivity, superoxide anion and proline content in leaf of S. kansuensis were lower than control group under the different CO₂ concentration.?4? With the elevated CO₂ concentration and increasing temperature, SOD, POD and CAT activity in leaf of S. kansuensis increased. SOD and CAT activity reached the maximum when the CO₂ concentration was 550 ?mol·mol-1 and the temperature was increased. The biggest increase of SOD and CAT activity were 54.9 % and 64. 8% at CO₂ concentration of 550 ?mol·mol-1.?5? The soluble sugar in leaf of S. kansuensis increased in different degree under interaction of atmospheric CO₂ concentration and temperature. Elevated temperature could significantly reduce the contents of soluble sugar when the CO₂ concentration was over 550 ?mol·mol-1. As a result, it was prevented to allocate and absorb the nutrient material of S. kansuensis when CO₂ concentration exceeded critical value of soluble sugar.Elevated temperature leaded to soluble protein in leaf of S. kansuensis to be maximized at CO₂ concentration of 550 ?mol·mol-1. When CO₂ concentration exceeded 550 ?mol·mol-1, protein synthesis was suppressed and structure was also destroyed. The speed of soluble protein content decreased significantly faster than the controlled temperature. The result showed that temperature had an significant influence on soluble protein in leaf of S. kansuensis. The results indicated that elevated CO₂ concentration and increasing temperature could increase germination index and germination rate of seeds, and increase the content of chlorophyll a, chlorophyll b, carotenoid, soluble sugar, soluble protein and SOD, POD and CAT activity in leaf, and reduce MDA, relative conductivity, superoxide anion and proline content in leaf of S. kansuensis. When CO₂ concentration reached 550 ?mol·mol-1, increasing CO₂ concentration and temperature could promote the growth of S. kansuensis to a certain degree.