NaCl处理对梭梭生长及生理生态特征的影响

Effects of salt treatments on the growth and ecophysiological characteristics of Haloxylon ammodendron

以1年生梭梭幼株为材料,采用盆栽试验研究不同浓度(0,50,100,200,400mmol/L)NaCl处理对梭梭生长状况及同化枝过氧化氢(H2O2)、丙二醛(MDA)含量、超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)、抗坏血酸过氧化物酶(APX)活性、水势、可溶性糖和脯氨酸含量的影响。结果表明,低浓度的NaCl处理(50mmol/L)对梭梭的生长具有促进作用,梭梭株高和基茎粗在400mmol/L NaCl处理下较对照显著减少,冠幅面积和同化枝、茎干重在NaCl浓度为≥200mmol/L时较对照开始显著减少,根干重在NaCl浓度为≥100mmol/L时较对照呈显著减少趋势。因此,NaCl胁迫对梭梭根生长的抑制作用大于对冠幅面积,同化枝和茎干重大于对株高和基茎粗。根冠比在NaCl浓度≥100mmol/L时较对照显著减少。H2O2和MDA含量在高浓度NaCl处理下较对照出现积累现象。低浓度NaCl处理下(≤100mmol/L),梭梭同化枝SOD、POD、CAT和APX活性较对照均有所提高,它们协调一致的共同作用,有效地清除植物体内的活性氧(reactive oxygen species,ROS),高浓度的NaCl处理下(≥200mmol/L),CAT和POD活性较对照开始降低,抗氧化酶系统对ROS的清除效率减弱。梭梭同化枝水势随NaCl处理浓度升高而降低。可溶性糖和脯氨酸含量随NaCl浓度增加较对照先上升后降低。

A pot experiment was conducted to study the influence of different concentrations （0, 50, 100, 200and 400 mmol/L） of NaCl on the growth, the contents of hydrogen peroxide （H2O2） and malondialdehyde （MDA）, the activities of superoxide dismutase （SOD）, catalase （CAT）, peroxidase （POD） and ascorbate peroxidase （APX）, water potential, and on the contents of soluble sugar and proline in the assimilation shoots of Haloxylon ammodendron. The growth of H. ammodendron was promoted at a lower NaCl concentration （50 mmol/L）. Compared with the control, plant height and basal stem diameter were significantly inhibited in the 400 mmol/L NaCl treatment, while crown area, dry mass of assimilation shoot and shoot dry mass were considerably reduced under NaCl treatments at concentrations ≥200 mmol/L and root dry mass was considerably reduced under NaCl treatments at concentrations ≥ 100 mmol/L. Thus, the suppressive effect on root dry mass was greater than on crown area, dry mass of assimilation shoot and shoot dry mass, which were more affected than plant height and basal stem diameter. Root/shoot ratios decreased markedly under NaCl treatments at concentrations ≥100 mmol/L compared with the control. Compared with the control, there were significant accumulations of H2O2 and MDA in the assimilation shoot of H. ammodendron at higher NaCl concentrations and the activities of SOD, POD, CAT and APX increased at low NaCl concentrations （4100 mmol/L）, suggesting that together they play an important role in the scavenging of reactive oxygen species. However, the activities of CAT and POD began to reduce at NaCl concentrations ≥200 mmol/L compared with the control,indicating the scavenging efficiency of the antioxidative enzyme system weakened. Water potential reduced with an increase in NaCl concentrations. The contents of soluble sugar and proline initially increased but then decreased compared with the control.