Effects Of Simulate Nitrogen Deposition And Lead Stress On The Growth And Breeding Of Davidia Involucrate

Davidia involucrate is a rare and endangered species in China,and the landscape-related research is very few,especially on climatic variation.The test used the D.involucrate as the experiment material and took advantage of the NH₄NO₃ to simulate the nitrogen deposition in natural environment and Pb（CH₃COO）₂ to simulate the lead in city environment,to realize two research goals:1.The growth and breeding of D.involucrate affected by simulate nitrogen deposition.2.Effects of simulate nitrogen deposition and lead stress on D.involucrate seedlings.And to reveal the possibility of D.involucrate access to landscape.The results were as follows:Compared with the control,the growth and breeding of D.involucrate were significantly suppressed on simulate nitrogen deposition,leaf number,leaf area,mean leaf area,leaf biomass,bract size,bract area,mean bract area,inflorescence diameter,pedicel length,pedicel diameter and ovary size significantly declined,and leaf mass per area and bract mass per area significantly increased.Besides,total fruit fresh weight,dry weight,water content increased first and then declined.On the other hand,the results showed that the high concentration of Pb²⁺ suppressed the photosynthesis and growth of D.involucrate seedlings,and the gas exchange characteristics,chlorophyll content and dry biomass accumulation declined.Though the moderate concentration of Pb²⁺ suppressed the photosynthesis of seedlings and decreased the chlorophyll content,the leaf area and biomass of root and leaf increased.Furthermore,simulate nitrogen deposition decreased the root biomass and increased the leaf chlorophyll content and leaf biomass.