模拟氮沉降对木荷和卷荚相思种子萌发的影响

【目的】研究氮沉降对2种林木种子萌发的影响，为南方森林的经营管理提供参考。【方法】以木荷和卷荚相思种子为试验材料，采用室内试验，选择2，6和12 g/L硝态氮（KNO₃）、铵态氮（(NH₄)₂SO₄）、混合氮（NH₄NO₃）进行氮沉降模拟试验，以蒸馏水为对照（CK），测定各处理木荷和卷荚相思种子的发芽率、相对发芽率、发芽指数、活力指数和发芽抑制率，在此基础上采用主成分分析综合评价不同处理对种子萌发的影响。【结果】随着KNO₃、 (NH₄)₂SO₄、NH₄NO₃ 质量浓度的升高，木荷和卷荚相思种子的发芽率、相对发芽率、发芽指数和活力指数均呈下降趋势，而发芽抑制率逐渐提高。由上述5种发芽指标可知，同一氮源下，其不同质量浓度对木荷和卷荚相思种子萌发的促进作用均表现为2 g/L>6 g/L>12 g/L；同一质量浓度下，3种氮源中以(NH₄)₂SO₄对木荷和卷荚相思种子萌发的促进作用最佳。主成分分析结果显示，木荷和卷荚相思均以主成分1能够反映原始变量80%以上的信息，因此选择主成分1对不同处理进行综合排名，结果在木荷和卷荚相思种子各处理中综合排名第1的均为2 g/L (NH₄)₂SO₄处理。【结论】当质量浓度为2~12 g/L 时，3种氮源对木荷和卷荚相思种子萌发的影响有差异，但最适宜的处理均为2 g/L (NH₄)₂SO₄。

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,germination 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),ammonium nitrogen ((NH₄)₂SO₄) and mixed nitrogen (NH₄NO₃) amounts,the germination rate,relative germination rate,germination index and vitality index of S. superba and A. cincinnata seeds showed a downward trend,while the germination inhibition rate was generally improved.According to above five indicators,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 principal 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.