涝渍胁迫对南方地区冬小麦氮素变化的影响

Effects of waterlogging stress on change in nitrogen of winter wheat in South of China

水位调控是实现稻田灌排联合调控的关键技术,在改善麦田生态环境方面发挥重要作用.在水位调控技术的基础上,采用田间试验和室内分析方法,研究了麦田水位调控下,冬小麦不同生育期、不同农田水层深度、地下水埋深下的氮素变化规律.研究结果表明:小麦受淹有利于地下水NH+4-N质量浓度的降低,受淹处理的地下水NH+4-N质量浓度均小于相同排水强度的没有受淹处理的.随着淹水时间的延长,NH+4-N的质量浓度降低速度缓慢.在没有淹水的情况下,地下水控制时间越长,则排水速度越慢,地下水有足够的时间与土壤及作物根系接触,因而越有利于降低地下水NH+4-N的质量浓度.麦田地下水NO-3-N质量浓度的变化规律表现为淹水有利于降低NO-3-N质量浓度;非淹水处理时,在返青分蘖期和拔节孕穗期控水后NO-3-N质量浓度略微升高,而在抽穗开花期和乳熟期NO-3-N质量浓度则显著升高.冬小麦全生育期内,NO-3-N均存在淋失的危险性.

Water level control is a key technique to realize the united regulation of irrigation-drainage in a wheat field and plays an important role in improving the ecological environment of the field. Based on the water level control technology,the change of nitrogen in deep groundwater in winter wheat farmland was studied by using field experiments and laboratory analysis at different growth stages and water depths. The results show that NH+4-N concentration in groundwater in flooding treatment is less than that in non-flooding treatment at the same drainage intensity,suggesting flooding helps to reduce NH+4-N concentration in groundwater. Unfortunately,with the prolonging flooding time,the decreasing rate of NH+4-N concentration gets slow. Under the condition without flooding,the longer the groundwater control time is,the slower the drainage rate is. The groundwater was caused to have enough time to contact with the soil and crop roots,which is in favor of the decreasing NH+4-N concentration. Additionally,flooding can reduce NO-3-N concentration as well. In the case without flooding,the NO-3-N concentration increases slightly at reviving-tillering and jointing-booting stages under water level control,but the NO-3-N concentration rises considerably at heading-flowering and milking stages. There is a danger of NO-3-N leaching in the whole growth period of winter wheat.