模拟盐胁迫对白榆种子发芽、出苗及幼苗生长的影响

Effects of simulated salt stress on seed germination,seedling emergence and growth of Ulmus pumila

以白榆为试材,研究模拟盐胁迫对种子萌发、出苗、幼苗生长及对其光合性能的影响,旨在为白榆耐盐种质资源的筛选提供理论依据。结果表明,随着盐胁迫浓度的增加,发芽率和发芽指数下降,发芽时间延长,幼苗出苗率、成苗率和存活率均呈下降趋势,盐胁迫抑制了幼苗苗高和根长生长。白榆幼苗阶段耐盐能力弱,出苗后一些幼苗受土壤盐分胁迫又陆续死亡。盐胁迫使叶片光合系统量子产额和能量分配比率(φPo、Ψo和φEo)、单位面积光合机构的比活性参数(ABS/CSM、TRO/CSM、ETO/CSM)、单位面积内反应中心的数量(RC/CSO和RC/CSM)、性能指数(PIABS和PICSM)和推动力(DFCSM)降低,单位面积光合机构的比活性参数(ABS/CSO)、热耗散的量子比率(φDo)和单位面积的热耗散(DIO/CSM)增加。苗期耐盐能力差,造成盐胁迫条件下成苗率低和苗期死亡是盐碱地白榆林下种子极少成苗的主要成因。

The effect of salt stress on seed germination,seedling emergence,growth and the photosynthetic performance of Ulmus pumila were studied to supply a theoretical basis for salt-tolerant germplasm selection in U.pumila.With an increasing concentration of salt stress,germination rate and germination index decreased,and the time of seedling germination was significantly delayed.The rate of emergence,planting percent and survival rate of seedlings decreased with an increase of salt concentration and salt stress reduced the growth of seedling height and root length of U.pumila.Because salt tolerance is weak in the seedling stage,a large number of seedlings died under salt stress.With an increase in salt stress,yields or flux ratios（φPo,Ψo and φEo）,phenomenological energy fluxes（ABS/CSM,TRO/CSM and ETO/CSM）.Density of reaction centers（RC/CSO and RC/CSM）,performance indexes（PIABS and PICSM） and driving force per unit area basis（DFCSM） decreased,while absorption flux per CS（ABS/CSO）,quantum yield for energy dissipation（φDo） and dissipated energy flux per CS（DIO/ CSM） increased.The reason that seeds of forest plant seedlings cannot grow when under salt stress is that salt tolerance is weak in the seedling stage,resulting in low planting percent and death of seedlings under salt stress.