NaCl胁迫对5个树种幼苗光合作用特性的影响

Influence of Salt Stress on Photosynthetic Characteristics of Five Tree Species Seedlings

以厚叶榆、木栓榆、黄连木、醉翁榆和榉树等1年生盆栽苗为研究对象,测定其在不同浓度NaCl胁迫下的光合作用指标,结果表明:(1)NaCl胁迫初、中期,随着浓度的增大和胁迫时间的延长,各种幼苗的净光合速率(Pn)、气孔导度(Cond)、胞间CO2浓度(Ci)和蒸腾速率(Tr)均呈下降趋势。叶面水气压亏缺(Vpdl)均有增加趋势,但增幅不明显。(2)NaCl胁迫后期,随盐分浓度的增加和时间的延长,Pn、Cond和Tr呈逐渐降低的的趋势,且降幅明显高于初期和中期。(3)5个树种树幼苗Pn的下降在盐胁迫初、中期是气孔限制的结果,后期为非气孔限制和气孔限制共同作用的结果。(4)不同的NaCl浓度与Pn、Cond、Ci和Tr呈负相关,与Vpdl呈正相关。在盐胁迫不同时期,醉翁榆Vpdl与NaCl浓度均呈显著或极显著的相关性;厚叶榆和木栓榆在初期和中期与NaCl浓度的相关性不显著,但后期相关性达到显著或极显著的水平;黄连木在初期与NaCl浓度的相关性不显著,中后期相关程度达到显著,而榉树在整个盐分胁迫期间Vpdl与不同的NaCl浓度均不显著相关。

Through experimental study on photosynthetic characteristics of five species potted seedlings under salt stress such as Ulmus crassifolio, U.thomasii, U.gaussenii, Zelkova schneideriana and Pistacia chinensis, in order to disclose the effect of salt stress on its photosynthesis parameters and lay theoretic foundation for introduction and cultivation.The results showed that： （1）with increase of NaCl concentration and time at prometaphase stage and interim its net production rate（Pn）,stomatal conductance（Cond）,carbon dioxide between cells（Ci） and transpiration rate（Tr） all presented a decreasing trend, meanwhile its vapor pressure devoid of leaves（Vpdl）presented a rising trend, but its decreasing amplitude was not obvious; （2）with increase of NaC1 concentration and time at later stage, its Pn,Ci and Tr came to display a decreasing trend,and its decreasing amplitudes were higher than those of both prometaphase stage and Interim; （3）at prometaphase stage the decreasing Pn of five tree species was caused by stomatal inhibition, but latterly it resulted from both non-stomatal inhibition and stomatal inhibition together, （4）there were negative correlations between Pn,Ci,Tr, cond,and NaCl concentrations,but positive correlations between Vpdl and NaCl concentrations. During different salt stress periods there were significant correlations in U.gaussenii between Vpdl and different NaCI concentrations. For U. crassifolia and U. thomasii there was a significant correlation between Vpdl and different NaCl concentrations latterly, but not notable at prometaphase stage and interim. There was not a significant correlation in Pistacia chinensis between Vpdl and different NaCI concentrations at prometaphase stage, but notable at interim stage and latterly; During the whole salt stress period there was not a significant correlation in Zelkova schneideriana between Vpdl and different NaCl concentrations.