盐胁迫对盐桦幼树光合特性的影响

[目的]盐胁迫对盐桦幼树光合特性的影响.[方法]利用土壤含盐量为1.0;、1.2;、1.4;、1.6;、1.8;、2.0;和2.2;七个盐浓度梯度,处理1年生盐桦实生苗,0;为对照CK,在生长的不同阶段分别测定叶片光合速率及其它生理指标.[结果]盐处理后,叶片净光合速率和气孔导度(Cond)均随NaCl浓度提高而显著降低;胞间CO_2浓度(Ci)、蒸腾速率Tr,随NaCl浓度提高呈先降低后升高的趋势;试验中1.6;NaCl胁迫下,盐桦幼树叶绿素含量提高,而1.6;～2.2;NaCl胁迫使叶绿素含量开始降低.[结论]NaCl胁迫下叶绿素含量提高是由于Na~+的吸收促进了生长,也有利于叶绿素的合成;1.4;～1.6;NaCl胁迫下叶绿素含量提高是由于盐胁迫下叶片生长缓慢,导致叶绿体收缩,产生 "浓缩"效应;1.4;NaCl胁迫下叶绿素含量仍然提高则可能是NaCl胁迫提高了叶绿素酶的活性,使光合色素合成减少、分解增加,从而使光合色素易于提取而导致了测得的叶绿素含量提高.

Influence of Salt Stress on Physiological Adaptability of Young Betula halophila Trees

【Objective and Method】The pot experiments were applied to study the effect of salt stress on the net photosynthetic rate(Pn)and other physiological properties of 1-year Betula halophila seedling.The seedlings were treated with NaCl concentrations of 1.0%,1.2%,1.4%,1.6%,1.8%,2.0%,2.2% and 0%(CK).【Result】Results show that the net photosynthetic rate(Pn) and stomatal conductance(Cond) were significantly decreased with the increasing of NaCl concentrantion;the intercellular CO2 concentration(Ci) and transpiration rate first were decreased then increased with the increasing of NaCl concentration.The chlorophyll content of Betula halophila seedling were increased after 1.6% NaCl treatment,but it was decreased with 1.6% and 2.2% NaCl treatment.【Conclusion】It was knowen that under NaCl stress,the chlorophyll content was increased and promoted the growth of the seeding by absorbing Na+,and advantageous to the synthesis of chlorophyll.When the seeding was treated by 1.4% and 1.6% NaCl,chloroplast contract arise from the slow growth of leaves,which caused contracting of chlorophore .Under treatment by 1.4% NaCl,the chlorophyll content was still increased.Photosynthetic pigment was refined more easily,so the determination of chlorophyll content was high.