水分胁迫下3 种针叶树幼苗抗旱性与硝酸还原酶和超氧化物歧化酶活性的关系

采用PEG (6000)根际渗透胁迫处理, 测定了水分胁迫下马尾松、火炬松、水杉幼苗硝酸还原酶(NR)和超氧化物歧化酶(SOD)活性变化。结果表明, 在水分胁迫下各苗木NR 和SOD 活力都呈下降趋势。NR 和SOD 活性以及RWC 两两间均呈明显的线性正相关。从3 个树种抗旱性与NR 和SOD 活性下降程度来看, 抗旱性较强的马尾松NR 和SOD 活性下降幅度均最小;抗旱性较差的水杉NR 活性下降幅度最大, SOD 居第2 位, 抗旱性居中的火炬松NR活性下降幅度居第2 位, 而SOD 居第1 位。表明3 个树种抗旱性与胁迫下NR 活性呈明显正相关, 而与SOD 活性没有明显的相关性。NR 活性可以作为这3 个树种间抗旱能力评定的有效生化指标, SOD 活性可以作为参考指标。表2 参15

Correlation of nitrate reductase and superoxide dismutase activities with drought resistance in seedlings of three conifer species under water stress

The activities of nitrate reductase (NR)and superoxide dismutase (SOD)were studied in seedlings of Pinus massoniana , Pinus taeda and Metasequoia glyptostrobides under osmotic stress by PEG (6000).The results showed that the activities of NR and SOD were all decreased in three seedlings under stress .The order of NR activity under stress was Pinus massoniana Pinus taeda Metasequoia glyptostroboides .The order of SOD activity was Pinus massoniana Metasequoia glyptostroboides Pinus taeda .Because the droughtresistance ablilty was Pinus massoniana Pinus taeda Metasequoia glyptostroboides (based on the former studies), there was a positive correlation between the activity of NR and drought-resistance in these seedlings under water stress , but there was no significant correlation between the SOD activity and drought-resistance .The conclusion obtained f rom this study reflected that the activity of NR could be used as an effective biochemical index for the criterion of drought-resistance in the three seedlings .