本文以墨西哥落羽杉（Taxodium mucronatum）三年生实生容器苗为材料，采用NaCl溶液浇灌的方法对墨西哥落羽杉苗木进行耐盐性研究，盐处理浓度分别设置为CK（0.1%）、0.3%、0.4%和0.5%，分别观测试验材料的盐害症状、苗高、地径、叶绿素总含量、相对电导率、脯氨酸含量、丙二醛含量、SOD酶活性以及植株不同部位Na 、K 、Ca2 含量等指标，结果表明：
- 离子可以参与渗透调节，随着盐处理浓度的增高，墨西哥落羽杉苗木体内的Na 含量越高，且不同部位Na 含量具有显著差异；而K 含量与Na 含量呈负相关，Ca2 含量也逐渐降低，这表明除了Na 打破了离子平衡外，还有K 和Ca2 被置换，抑制了吸收。
Effects of salting on physiological and biochemical characteristics of Taxodium mucronatum
Based on the Mexican cypress fir (Taxodium mucronatum) born three years container seedlings as material, adopt the method of NaCl solution to water salt resistance was studied for the nursery stock, salt processing concentration were set to CK (0.1%), 0.3%, 0.4% and 0.5%, respectively, observing salt injury symptoms of test materials, seedling height, ground diameter, total chlorophyll content, relative electric conductivity, proline content, mda content, SOD activity and different parts of the plant of Na , K , Ca2 content indicators, such as the results showed that:
(1) under the stress of different concentrations of salt, all the pinus chinensis were damaged to varying degrees, and their leaves appeared yellow and withered, but no death occurred during the 90d test period, so the survival rate was 100% within the 90d test period. During the experiment period, different concentrations of treatment had a promoting effect on the seedling height growth and ground diameter growth of pinus chinensis, while the growth of the 0.5% treatment group was higher than that of the control group, indicating that appropriate salt stress could promote seedling growth.
(2) salinity stress will destroy the chloroplast structure, resulting in the reduction of chlorophyll content. The chlorophyll content in the treatment group was lower than that in the control group under the salinity stress of different concentrations, indicating that the chlorophyll content decreased with the increase of salt concentration. The relative conductivity reflects the degree of cell membrane damage. The relative electrical conductivity of seedlings decreased after salt stress, which indicated that seedlings had certain adaptability to salt stress. The relative conductivity of the control group was higher than that of the experimental group, indicating that the relative conductivity increased with the increase of salt concentration. Salinity stress can lead to proline accumulation, which can reduce the damage to seedlings. The proline content of seedlings under different treatments increased in the later stage, indicating that salinity stress did not harm seedlings to some extent. The content of malondialdehyde could represent the degree of seedling damage. The content of malondialdehyde in the treatment groups with different concentrations showed a trend of rising first and then falling, and the difference between the groups was not significant, indicating that the Mexican taxus alpinia was sensitive to the saline environment and the degree of damage was small. The high activity of SOD enzyme is beneficial to protect the membrane lipid from attack and avoid the harm of peroxidation. The activity of SOD enzyme increases with the increase of the salt concentration, indicating that the Mexican cedar has certain salt tolerance.
（3）Ions can involve in osmotic regulation, and Na content increases with the increase of salt concentration, and the difference is very significant. However, K content was negatively correlated with Na content, and Ca2 gradually decreased, indicating that in addition to Na breaking the ion balance, K and Ca2 were replaced, inhibiting absorption.
Key words:Taxodium mucronatum; Salt stress; Physiological index; Salt ions