可见分光光度法测定碱胁迫中合欢幼苗的生理指标

为检测合欢幼苗的抗碱胁迫能力，文章试验利用可见分光光度法测定了碱胁迫下合欢幼苗体内的丙二醛、可溶性糖、脯氨酸含量及POD、SOD活性，分析这些生理指标在不同处理浓度、不同处理时间下的变化规律，探求碱胁迫下合欢幼苗的抗逆生理机制。随着Na₂CO₃处理浓度的增加，幼苗叶片中MDA和可溶性糖含量，均呈递增趋势，当处理浓度低于75 mmol·L-1,两者含量变化较平缓，而浓度高于75 mmol·L-1时，则含量急剧增加，各处理间差异显著；脯氨酸含量也呈递增趋势，当处理浓度低于100 mmol·L-1,变化较平缓，浓度高于100 mmol·L-1时，含量则急剧增加，各处理间差异显著；SOD和POD活性变化趋势一致，都呈单峰曲线变化，但两者活性最大值所对应的处理浓度不同，分别为50和75 mmol·L-1。此外，随着胁迫时间的延长，同一浓度处理的丙二醛含量逐步增加，而脯氨酸、可溶性糖含量、SOD、POD活性变化较复杂，无明显规律性。

Determination of Physiological Indices in Albizzia Julibrissin Durazz Seedlings under Alkaline Stress with Visible Spectrophotometry

There is a large area of saline-alkali soil in our country, and soil alkalization is always a problem affecting urban gardening. To examine the capacity of alkaline resistance of Albizzia julibrissin Durazz seedlings, the contents of MDA, soluble sugar and proline, and the activity of POD and SOD in Albizzia julibrissin durazz tree body were measured by means of visible spectrophotometry. Also, the change patterns of the five indexes with different treatment concentration and time were analyzed. Attempts were then made to elucidate the physiological mechanism of how alkaline stress affects the growth of the Albizzia julibrissin durazz tree, which could provide theoretical foundation for planting and gardening and an approach to dealing with the difficulties in planting and gardening in saline and alkaline area. The results showed that with the increase in Na2 CO3 concentration, the contents of MDA and soluble sugar in the leaves slowly ascended when the treatment concentration was lower than 75 mmol x L(-1), and then rapidly increased when the treatment concentration was higher than 75 mmol x L(-1); There were significant differences between different treatments. Proline content exhibited the same change pattern with MDA and soluble sugar. It slowly ascended when the treatment concentration was lower than 100 mmol x L(-1), whereas it sharply increased when the treatment concentration was above 100 mmol x L(-1); The changes in SOD and POD were similar, showing a unimodal pattern. However, the treatment concentration corresponding to the maximum of SOD and POD was 50 and 75 mmol x L(-1), respectively. With the changes in stress time, in addition, the contents of MDA treated with the same concentration increased gradually. However, praline, soluble sugar, SOD and POD changed irregularly. These results indicated that Albizzia julibrissin Durazz could resist the alkaline stress by modulating values of physical indexes such as the contents of MDA, soluble sugar and proline and the activity of POD and SOD.