Influence Of Drought Stress And Sand Burial To Phenotypic Plasticity Of Desert Plant

Artemisia ordosica and Nitraria tangutorum, which play an important role in desert ecosystem stability, are important constructive and dominant species of sand-living vegetations and widely distributed in arid and semiarid areas. Three different provenances of Artemisia ordosica from Mu Us Sandy land(WSOR),Kubuqi desert(DEOR),Desert-steppe transitional zone(HYOR),which grow in different soil moisture, were investigated in morphology and physiology, to have a knowledge of the mechanism of adaptation of drought environment of Artemisia ordosica and compare with the drought-resistant ability of three different provenances of Artemisia ordosica,the response model of morphological plasticity of three different provenances of Artemisia ordosica under drought environment and compare with the morphological plasticity index of three different provenancesof Artemisia ordosica. Meanwhile, the phenotypic plasticity of morphology, biomass allocation and photosynthesis of Nitraria tangutorumwere studied under different sand burial depth of 0cm, 5cm, 10 cm, 15 cm.The results showed that:1.The response of morphology characteristics, photosynthetic pigment conten, content of Starch, soluble sugars and NSC of three different provenances of Artemisia ordosica to drought stress is consistent,namely as the drought stress increased,(1) plant height, stem diameter, leaf area and SLA of Artemisia ordosica,show a trend of decrease gradually. the plant height, stem size, leaf area of Artemisia ordosica from Kubuqi desert is larger than Artemisia ordosica from Mu Us Sandy land and Desert-steppe transitional zone under the severe drought stress, While Sla of Artemisia ordosica from Kubuqi desert is less than Artemisia ordosica from Mu Us Sandy land and Desert-steppe transitional zone.(2) Chla, Chlb, Chl(a+b), Car, Chla/b and Car/Chl content of leaf of Artemisia ordosica,show a trend of increase first and then decrease. Content of Chla, Chlb, Chl(a+b) of leaf of Artemisia ordosica from Kubuqi desert is larger than Artemisia ordosica from Mu Us Sandy land and Desert-steppe transitional zone under the severe drought stress,while the difference of content of Car and Car/Chl of three different provenances of leaf of Artemisia ordosica is not significant, and Chla/b of Artemisia ordosica from Desert-steppe transitional zone is largest, Artemisia ordosica from Mu Us Sandy land is the second, and Artemisia ordosica from Kubuqi desert is the least.(3) Content of Starch, soluble sugars and NSC of three different provenances of leaf of Artemisia ordosica,show a trend of decrease first and then increase. Content of Starch, soluble sugars and NSC of leaf of Artemisia ordosica from Desert-steppe transitional zone is higher than Artemisia ordosica from Kubuqi desert and Mu Us Sandy land under severe drought stress, and Content of Starch,soluble sugars and NSC of leaf of Artemisia ordosica from Kubuqi desert is higher than Artemisia ordosica from Mu Us Sandy land. In conclusion, we find that the drought resistance of Artemisia ordosica from Kubuqi desert is stonger than Artemisia ordosica from Mu Us Sandy land and Desert-steppe transitional zone.2.The response model of morphological plasticity of three different provenances of Artemisia ordosica under drought environment is similar. as the drought stress increased, RGR and SLA showed a trend of decrease gradually, while the trend of R/S is opposite. Morphological plasticity index of three different provenances of Artemisia ordosica is not significant, butthe difference of average size of morphological plasticity index of three different provenances of Artemisia ordosica is significant, such as the average size of morphological plasticity index of Artemisia ordosica from Kubuqi desert is greater than Artemisia ordosica from Mu Us Sandy land. In conclusion, the response model of morphological plasticity of three different provenances of Artemisia ordosica under drought environment is similar.3.With the depth of sand burial increased, the height, 15 cm stem diameter, leaf area, leaf number, numbers of adventitious rootand the biomass of above-ground, the total biomass of Nitraria tangutorum decreased. and the length, diameter of adventitious root and the below-ground biomass firstly increased and then decreased with the increase of depth of sand burial; Daily average of net photosynthetic rate, transpiration rate and stomatal conductance of Nitraria tangutorum increased gradually. the difference of photosynthetic parameters of Nitraria tangutorum is not significant.at mild sand burial, while the difference of photosynthetic parameters of Nitraria tangutorum is significantas the depth of sand burial is over a certaion range. Chlorophyll contents of Nitraria tangutorum are almost the same at the depth of 5cm and 10cm; when the depth of sand burial isover a certain range, Chlorophyll contents of Nitraria tangutorum increased significantly. We conclude that the phenotypic plasticity of morphology, biomass allocation and photosynthesis of Nitraria tangutorum is greater under different depth of sand burial, and when the depth of sand burial is over a certain range, the phenotypic plasticity of photosynthetic parameters of Nitraria tangutorumcould be greater.