Adaptive Characters Of Elaeocarpus Glabripetalus Under Simulated Nitrogen Deposition And Cadmium Stress

Elaeocarpus glabripetalus is one of the common garden tree species in China.Numerous studies have shown that it has strong adaptability to environment stress.In this study,one-year-old Elaeocarpus glabripetalus Seedlings was used for plot experiment with four levels of treatment,N(90 kg·ha-1·yr-1 N as NH4NO3),Cd(100 mg?kg-1 Cd as Cd Cl2),NCd(90 kg·ha-1·yr-1 N as NH4NO3 + 100 mg?kg-1 Cd as Cd Cl2).And We measured growth indexes,gas exchange parameters,water indices,N metabolism enzymes and glutathione.isohydric/anisohydric were introduced to describe resource acquisition strategy and time effect of carbon-water balance.The main results of the study are summarized below:(1)E.glabripetalus was found to be phenotypic sensitive to Cd stress,but had no significant damage on its photosynthetic system under Cd stress.Whether in August,September or October,Cd and NCd treatment showed little inhibition on fluorescence parameters.Even in October,Cd significantly increased Fv/Fm and NCd promoted Fv/Fm,q P and ETR.On the other hand,Cd significantly promoted NR and Ni R enzyme activities in the roots.All the phenomenons showed high Cd tolerance.N treatment led to Fine-root growth and high Ni R enzyme activities,while NCd promoted SLA and root morphology parameters.Both indicated that N improved nutrient use capacity,which helps with nitrogen metabolism and Cd chelation.(2)Net photosynthesis(Pn)and water potential(?l)showed a close revelation under the treatment of N,while stomatal conductance(Cond)and ?l showed some correlation.And thus,E.glabripetalu showed some characteristics of anisohydric under N treatment,but biased towards isohydric under Cd treatment.However,there were no significant revelation between gas exchange parameters and ?l under NCd treatment.What's more,NCd had less transpiration(Trmmol)and Cond.And then it can be considered that NCd was biased towards isohydric.(3)The time effect has a significant effect on the photosynthesis-water strategy of E.glabripetalus.In August,water regulation took the dominant position.Stomata become an important factor limiting the photosynthetic efficiency of E.glabripetalus.In September,E.glabripetalus biased towards efficiency photosynthesis and water use efficiency.In October,due to the limitation of other environmental factors such as light conditions,improving photosynthetic water use efficiency became the main strategy.In summary,E.glabripetalus presented high adaptability for stress.And E.glabripetalus respectively adapt fast,slow and water-maintaining based fast resource strategy separately under N,Cd and NCd treatment.