Tolerance Of Sambucus Coreana And Acer Ginnala To Soil NaHCO₃ Stress

Sambucus coreana and Acer ginnala were native trees in Northeast,which had high tolerance and adaptability to the environment around itself and played an important role in beautifying cities and improving the environment.The changes in growth,physiological and biochemical indexes of one-year-old Sambucus coreana and Acer ginnala seedlings under different NaHCO₃ stress intensity(CK,1.0,2.0,4.0 g NaHCO₃·kg^-1 media,named respectively as control,mild stress,moderate stress,severe stress) were tested.The main results were as follows:(1) Under mild stress,Sambucus coreana and Acer ginnala could grow normally,while the growth of the two trees was prohibited under moderate and severe stress.Compared with ck,the relative height growth of Sambucus coreana decreased by 35.7%and 87.3%under moderate and severe stress,the relative height growth of Acer ginnala decreased by 32.1% and 106%under moderate and severe stress.The survival of Sambucus coreana and Acer ginnala under moderate and severe stress was 90%,65%and 75%,55%respectively.(2) The photosynthesis of Sambucus coreana and Acer ginnala was prohibited under salt stress.Compared with ck,the photosynthesis rate of Sambucus coreana under different NaHCO₃ stress intensity decreased by 30.9%,38.3%and 55.9%respectively,while that of Acer ginnala decreased by 32%,49.4%and 57.1%.The decreasing scale of photosynthe-sis rate of Sambucus coreana was relatively small.The main factor leading to decreasing in photosynthesis rate of Sambucus coreana was non-stomatal limitation,while that of Acer ginnala was stomatal limitation.(3) Under salt stress,the contents of proline,soluble sugar and soluble protein all increased obviously,which played a part in osmoregulation.At long-time stress stage, compared to corresponding control,the content of soluble sugar of Sambucus coreana and Acer ginnala under mild,moderate and severe stress increased by 46.7%,38.3%,51.9%and 15.6%,31.8%,22.7%,respectively.(4) Under salt stress,the leaves of Sambucus coreana and Acer ginnala seedlings all suffered from some damage.At long-time stress stage,compared to corresponding control,the production rate of O₂^- ofSambucus coreana under I and H treatment increased by 49.1%and 55.2%,while that of Acer ginnala increased three times.Compared with ck,the electrolyte leakage of Sambucus coreana under H treatment increased by 40.7%,and it did not changed obviously under I and L treatment,while that of Acer ginnala under mild,moderate and severe stress increased by 20%,38.5%and 85.3%.The electrolyte leakage of Sambucus coreana changed slightly,which exhibited their salt tolerance,while that of Acer ginnala increased with large scale.(5) Under salt stress,Sambucus coreana and Acer ginnala remained high ASA and GSH contents in their leaves.Furthermore,Sambucus coreana had a high GR activity,and Acer ginnala had high APX and POD activities.Compared to corresponding control,the content of GSH of Sambucus coreana under mild,moderate and severe stress increased by 68.5%,54.5%and 90.4%at middle stress stage,while that of Acer ginnala increased by 87.9%, 124.9%and 96.9%at long-time stress stage,respectively.Sambucus coreana and Acer ginnala had tolerance to lower salt stress and could bear the soil environment with 1 g·kg^-1 NaHCO₃.The tolerance against carbonate stress of Sambucus coreana was better than that of Acer ginnala.