以3 个楸树(Catalpa bungei C. A. Meyer)无性系(02-2-5、YQ1 和07-1)扦插苗为研究对象,对质量浓度0. 00%(对照)、0. 10%、0. 20%、0. 25%、0. 30%和0. 40% NaCl 胁迫条件下其细根(直径Ф<2 mm)和粗根(Ф≥2 mm)的长度、表面积和体积等形态学特征以及根系活力的变化规律进行了研究。结果表明:随NaCl 质量浓度的提高,各无性系细根及粗根的长度、表面积和体积以及根系活力均逐渐降低,且均明显低于对照,部分处理与对照间的差异具有统计学意义(P<0. 05)。在NaCl 胁迫条件下,各无性系间根长和根表面积降幅的差异不明显且无统计学意义(P>0. 05);但在中度(NaCl 质量浓度0. 20%和0. 25%)及重度(NaCl 质量浓度0. 30% 和0. 40%)胁迫条件下,无性系02-2-5 根体积的降幅显著小于另外2 个无性系;而在NaCl 胁迫条件下无性系02-2-5 根系活力的降幅也显著小于另外2 个无性系。研究结果显示:在NaCl 胁迫条件下3 个楸树无性系扦插苗根系的生长均受到抑制,但各无性系对NaCl 胁迫的耐性有一定差异,其中无性系02-2-5 对NaCl 胁迫的耐性较强;此外,根系活力或其降幅可作为楸树无性系耐盐能力的评价指标之一。

Taking cutting seedlings of three clones (02-2-5, YQ1 and 07-1) of Catalpa bungei  C. A. Meyer as experimental materials, change regularity of morphological characteristics including length, surface area and volume of fine root (diameter Ф<2 mm) and coarse root (Ф≥2 mm) and root activity was studied under condition of NaCl stress with mass ratios of 0. 00% (CK), 0. 10%, 0. 20%, 0. 25%, 0.30% and 0. 40%. The results show that length, surface area and volume of fine root and coarse root and root activity of three clones gradually decrease with rising of NaCl mass ratio, which are all obviously lower than those of the control and there is the statistical significance (P<0. 05) in differences of some treatments with those of the control. Under condition of NaCl stress, there is no obvious difference in decreasing range of root length and root surface area among three clones without statistical significance (P>0. 05). But under conditions of medium (NaCl mass ratio of 0. 20% and 0. 25%) and heavy (NaCl mass ratio of 0. 30% and 0. 40%) stresses, decreasing range of root volume of clone 02 -2 -5 is significantly lower than that of other two clones, and under NaCl stress, decreasing range of root activity of clone 02-2-5 is also significantly lower than that of other two clones. It is suggested that root growth of cutting  seedlings of three clones of C. bungei all could be inhibited under NaCl stress, but the tolerance of three clones to NaCl stress is different, in which, the tolerance of clone 02-2-5 to NaCl stress is stronger. Moreover, root activity or its decreasing range can be used as one of evaluating indexes for salt tolerance of C. bungei clones.