| 摘要: |
| 【目的】揭示前期不同水分胁迫条件下局部恢复供水时玉米生长及水分吸收的动态变化，了解玉米生长对土壤水分条件变化的响应特征。【方法】以PEG 6000模拟水分胁迫，采用分根方法，以玉米幼苗整个根系均持续正常供水为对照（CK），在全部根系经受-0.4 MPa预水分胁迫0，1，3和6 d后，对1/2根区恢复正常供水，另1/2根区维持-0.4 MPa胁迫水平，在局部供应0，0.25，0.5，1，3，5，7和9 d后，测定幼苗各部分的生长及水分吸收状况。【结果】胁迫0 d，即前期正常供应后局部-0.4 MPa胁迫，会在一定时间内刺激供应区根系导水率与根干物质量的补偿效应；局部供应3 d内维持玉米幼苗地上部干物质量与CK持平，继续局部亏水会使地上部干物质量及根系导水率、尤其胁迫侧的根系导水率、根长和根干物质量明显降低，而对供应区根干物质量、根长、根面积无显著影响。对于-0.4 MPa胁迫1，3，6 d，玉米叶片相对含水量分别在局部复水3，5，5 d时恢复至CK水平(胁迫0 d始终与CK持平)；地上部干物质量不能完全恢复，但其占CK的相对比例最终趋于稳定；复水侧根系导水率、根干物质量、根长与根面积会有一定的恢复，但复水9 d时仍不能恢复到CK水平，恢复程度均随胁迫时长的增大而减小；持续胁迫侧根系仍持续下降。根冠比有所不同：胁迫时间越长根冠比越大，局部复水后各处理根冠比均呈增大趋势，胁迫0，1，3，6 d各处理显著大于对照的时间分别为局部复水后7，3，1和1 d，增幅随局部复水时间延长而减缓（除胁迫0 d外）。【结论】作物对局部复水的响应与前期亏水持续时间有关，适当的亏水可通过局部复水得到恢复。 |
| 关键词: 玉米幼苗 胁迫时长 局部复水 根系导水率 叶片水分状况 干物质累积分配 |
| DOI： |
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| 基金项目:国家自然科学基金项目（51079124）；中央高校基本科研业务费专项（QN2011067） |
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| Response of maize seedling to partial rewatering after varing stress time |
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WANG Li,NIU Xiaoli,YANG Shuohuan,et al
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| Abstract: |
| 【Objective】This study aimed to reveal the dynamic changes and influencing factors of maize growth and absorption capacity under partial water resupply after different previous water stresses.【Method】Maize seedlings were prepared using split-root hydroponic technique,with PEG 6000 simulating water stress.All roots with normal water supply were used as control treatment,and 4 previous stress times (0,1,3 and 6 d) under -0.4 MPa were treatment levels.All roots were treated with uniform water stress each day before half roots were treated with normal water level while half roots were treated with water stress.The growth and absorption status of each part of seedling was monitored continuously and dynamically at different hours after treatments (0,0.25,0.5,1,3,5,7 and 9 d).【Result】After previous stress time of 0 d,partial water supply stimulated the compensation effect of the hydraulic conductivity and the root try weight at the non-stressed sub-root zone within a certain period of time.The dry weights of corn seedlings maintained the same as the CK in 3 days,while the root dry weight,LR and root hydraulic conductivity with continuous local water deficit decreased significantly.But it had no significant influence on root dry weight,LR and AR of normal water supply parts.By controlling -0.4 MPa water stress level for 1,3,and 6 d and rewatering afterwards,the relative leaf water content recovered to CK after 3,5,and 5 d,respectively.Aboveground dry matter quantity was not fully recovered,but the relative proportion of CK eventually stabilized.The hydraulic conductivity,root try weight,LR and AR of non-stressed sub root had certain recovery,but not to CK 9 days after partial resupply.The degree of recovery decreased with the increase of stress duration.The non-stressed sub-root continued to decline.The root-shoot ratio showed a trend of increase after water resupply,the root-shoot ratios at 0,1,3 and 6 d previous stress treatments were significantly higher than CK 7,3,1 and 1 d after partial resupply.The increase of root-shoot ratio slowed down with the increase of water recovery time (except 0 d). 【Conclusion】Response of crops to partial water resupply was related to pre-stress duration,and the effects of appropriate stress duration can be recovered through partial water resupply. |
| Key words: maize seedling previous stress duration partial rewatering root hydraulic conductance leaf water status accumulation and allocation of biomass |
