淹水胁迫下不同玉米品种根结构及呼吸代谢差异

【目的】研究不同玉米品种幼苗根显微结构及呼吸代谢对淹水胁迫的响应差异。【方法】以耐涝性不同的玉米品种浚单20（耐涝性强）和登海662（耐涝性弱）为试材，设CK、淹水2、4、6、8 d共5个处理，比较淹水胁迫下不同玉米品种苗期根结构及呼吸代谢差异。【结果】淹水后，两品种幼苗的根干重、根总长度、根系活力均明显下降，随着淹水天数增加，下降幅度增大，两品种间表现为登海662各指标下降幅度显著高于浚单20。其中淹水8 d时，登海662和浚单20根干重分别比对照降低29.7%和12.1%，根系活力分别比对照降低30.6%和8.7%。淹水增加了两品种玉米根气腔面积和根孔积率，平均比对照增加3.9倍和2.8倍，且随着淹水时间延长而增大。淹水使玉米根系的乙醇脱氢酶（ADH）、丙酮酸脱羧酶（PDC）和乳酸脱氢酶（LDH）活性比对照平均增加27.7%、55.0%和2.6倍，其中登海662的增加幅度大于浚单20，且差异显著。【结论】不同玉米品种根系对淹水胁迫的响应不同，耐涝品种具有完整根结构、较高的根系活力、大面积较发达的通气组织、适度的无氧呼吸代谢，因而能够更好地适应淹水胁迫，提高干物质生产能力。

Difference in Root Structure and Respiration Metabolism Between Two Maize Cultivars Under Waterlogging Stress

【Objective】The objective of this study was to identify the difference in root structure and respiration metabolism between two maize cultivars under waterlogging stress in seedling growth.【Method】A pot experiment with two maize cultivars DH662 (a susceptible maize genotype) and XD20 (a tolerant one) was conducted at scientific and educational campus of Henan Agricultural university. CK and 2, 4, 6, 8 days of waterlogging were designed for the two cultivars. The differences in root structure and respiration metabolism between two cultivars were studied. 【Result】The results showed that the root dry weight, root length, root activity of two cultivars decreased with the increase of waterlogging days. And the decreases in DH662 were more significantly than in XD20. The root dry weight in DH662 and XD20 decreased by 29.7% and 12.1%, while root activity decreased by 30.6% and 8.7% as compared with CK treatment after 8 days of waterlogging. The number of aerenchyma, the aerenchyma area and the porosity of two cultivars increased with the increase of waterlogging days. The average aerenchyma area and root porosity of two cultivars increased by 3.9 times and 2.8 times than CK treatment after 6 days of waterlogging. The average activity of alcohol dehydrogenase, pyruvate decarboxylase and lactate dehydrogenase in two cultivars increased by 27.7%, 55.0% and 2.6 times than CK treatment. And the increases in DH662 were more significantly than in XD20. 【Conclusion】Different cultivars had different responses mechanism in their tolerance to waterlogging in seedling growth. A tolerant maize cultivar had intact root structure, higher root activity and developed aerenchyma. And the anaerobic respiration was moderate. So the tolerant maize cultivar could resist waterlogging stress and increase root dry weight.