Effects of simulated nitrogen deposition on seed germination of Schima superba and Acacia cincinnata
[Objective]This study investigated the effects of nitrogen deposition on seed germination of 2 tree species to provide reference for forest management in southern China.[Method]Schima superba and Acacia cincinnata seeds were selected for laboratory experiments with simulated nitrogen deposition of 2,6 and 12 g/L nitrate nitrogen(KNO3),ammonium nitrogen((NH4)2SO4)and mixed nitrogen(NH4NO3).Distilled water was used as control(CK).The germination rate,relative germination rate,ger-mination index,vitality index and germination inhibition rate of S.superba and A.cincinnata seeds were determined.On this basis,principal component analysis was used to comprehensively evaluate the effects of different treatments on seed germination.[Result]With the increase of nitrate nitrogen(KNO3),ammo-nium nitrogen((NH4)2SO4)and mixed nitrogen(NH4NO3)amounts,the germination rate,relative ger-mination rate,germination index and vitality index of S.superba and A.cincinnata seeds showed a down-ward trend,while the germination inhibition rate was generally improved.According to above five indica-tors,the promoting effects of same nitrogen sources at different concentrations on seed germination of S.superba and A.cincinnata were in the order of 2 g/L＞6 g/L＞12 g/L.Under same concentrations,(NH4)2SO4 had the best promoting effect on seed germination of S.superba and A.cincinnata.The prin-cipal component analysis showed that principal component 1 could reflect more than 80％of the original variable in both S.superba and A.cincinnata seeds.Therefore,the principal component 1 was selected for comprehensive ranking of different treatments and it showed that the treatment of 2 g/L(NH4)2SO4 was the best.[Conclusion]The effects of three nitrogen sources on seed germination of S.superba and A.cincinnata at different concentrations of 2-12 g/L were different,but 2 g/L(NH4)2SO4 was the best for both species.
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