Drought Resistance Of Five Kinds Of Native Greening Tree Species In Baoji City

Drought is one of the main limiting factors for plant growth and development.Tree species have different ability to adapt to and resist water-deficient environment during long-term evolution.To discover excellent drought-tolerant tree species in native tree species is important for the formation of stable urban greening system.In this study,Celastrus orbiculatus,C.angulatus,Parthenocissus tricuspidata,Evodia deniellii and Pyracantha fortuneana were selected as experimental materials for the local greening species in Baoji City.Pot experiment control method was used to investigate the growth indicators?seedling height,ground diameter,wilting index?,physiological indicators?leaf water content,Chla content,Chlb content and Chla/b,Pn and Tr?,and biochemical indicators?Pro,SS,MDA,and Tr?under the different drought conditions,to analyze the water use efficiency?WUE?.Membership function values was also used to evaluate the differences of drought resistance among five tree species.Aim to provide a certain theoretical basis for the tree species selection of urban greening in Baoji City.The research results are as follows:?1?With the increase of drought stress,soil water content decreased,and the stress symptoms of Celastrus orbiculatus,C.angulatus and Evodia deniellii were more obvious;The growth rate of seedling height of C.angulatus decreased the most,reaching 3.74%;the growth rate of ground diameter of Celastrus orbiculatus decreased the most,reaching 2.25%,and the growth rate of ground height and diameter of Pyracantha fortuneana decreased the least.?2?With the increase of drought stress,the leaf water content and chlorophyll a/b value of five tree species showed a trend of decreasing.The leaf water content of Celastrus orbiculatus decreased the most,which was 48.79%.Evodia deniellii The chlorophyll a/b value decreased the most,being 26.19%;the transpiration rate and net photosynthetic rate were higher than the Parthenocissus tricuspidata,which were 5.84?mol·m^-2·s^-11 and6.68?mol·m^-2·s^-1;Pyracantha fortuneana has the highest water use efficiency of 1.29;Evodia deniellii has a maximum net photosynthetic rate of 12.46?mol·m^-2·s^-1;Celastrus orbiculatus the dark respiration rate was 1.61?mol·m^-2·s^-1;the apparent quantum efficiency of C.angulatus was 0.0696?mol·m^-2·s^-1.?3?With the increase of drought stress,the contents of malondialdehyde?MDA?,soluble sugar?SS?and proline?Pro?increased in different leaves,and the proline of Celastrus angulatus was increased.The increase of?Pro?content was up to 48.48 times;the increase of malondialdehyde?MDA?content of Evodia deniellii was up to 146%;the soluble sugar of Celastrus angulatus was up to 1.58 times.?4?In this experiment,the fuzzy mathematics membership function method was u sed to comprehensively evaluate the drought resistance ability of five tree species.Th e drought resistance was in the order of Parthenocissus tricuspidata>Pyracantha fort uneana>Evodia deniellii>Celastrus orbiculatus>C.angulatus,the average members hip function values are 0.73,0.52,0.31,0.30,0.28 respectively,which is consistent with the morphological changes of plants under drought stress.