Rhizosphere hydrophobicity limits root water uptake after drying and subsequent rewetting
Rhizosphere hydrophobicity limits root water uptake after drying and subsequent rewetting
复制标题
DOI：
10.1007/s11104-018-3677-7
复制
发表时间：
2018-05
期刊：
影响因子：
4.9
通讯作者：
M. Zarebanadkouki;M. Ahmed;Clemens Hedwig;P. Benard;S. Kostka;Anders Kastner;A. Carminati
中科院分区：
文献类型：
--
作者：
M. Zarebanadkouki;M. Ahmed;Clemens Hedwig;P. Benard;S. Kostka;Anders Kastner;A. Carminati
背景和目的最近的实验表明，几种植物的根际在严重干燥和随后的再润湿后会暂时变成疏水的。是否这样的疏水性限制根吸水是未知的。MethodsA一组实验进行测试是否根际水排斥性产生负面影响根吸水。为此，使用商业表面活性剂作为再润湿剂，以促进桑迪土壤中羽扇豆（白羽扇豆）根际的润湿性。羽扇豆植物生长在根箱中，并进行严格的干燥循环。然后，一半的植物用水灌溉，一半用表面活性剂溶液灌溉。利用时间序列中子照相技术对灌溉过程中根际水分再分布进行了监测。在第二个实验装置中，羽扇豆生长在桑迪土壤中，该土壤被分成五个垂直隔室，隔室由1 cm厚的粗砂层（用作毛细屏障）隔开。将水和表面活性剂注入不同的隔室中，用中子照相术监测灌溉隔室以外的根组织的再水化2-3 h。根复水率被用来估计整个根-土interfaces.ResultsThe羽扇豆根在桑迪土壤灌溉水的根际保持部分干燥至少2-3小时，而它被迅速复湿时，灌溉与表面活性剂。水流入的根与表面活性剂溶液灌溉的速度比6.5倍，到根灌溉用水conclusionsThese结果证明，在桑迪土壤中的羽扇豆根际的水排斥性限制在第一个两到三个小时后灌溉的水通量到根和根的再水化。这可能并不总是负面的，因为它可以限制水分从根部流失到干燥的土壤中，从而避免严重的根部脱水。
Background and AimsRecent experiments showed that rhizosphere of several plant species turns temporarily hydrophobic after severe drying and subsequent rewetting. Whether or not such hydrophobicity limits root water uptake is not known.MethodsA set of experiments was performed to test whether rhizosphere water repellency negatively affects root water uptake. To this end, a commercial surfactant was used as a rewetting agent to facilitate the wettability of the rhizosphere of lupins (Lupinus albus) in a sandy soil. Lupin plants were grown in rhizoboxes and were subjected to a severe drying cycle. Then half of the plants were irrigated with water and half with the surfactant solution. Time-series neutron radiography technique was used to monitor water redistribution in the rhizosphere during irrigation. In a second experimental set-up, lupins were grown in a sandy soil partitioned in five vertical compartments separated by a 1-cm layer of coarse sand (acting as a capillary barrier). Water and surfactant were injected in different compartments and the rehydration of the root tissues beyond the irrigated compartments was monitored with neutron radiography for 2–3 h. Root rehydration rates were used to estimate the water fluxes across the root-soil interface.ResultsThe rhizosphere of lupin roots in sandy soil irrigated with water remained partly dry for at least 2–3 h, while it was rapidly rewetted when irrigated with surfactant. Water flow into the roots irrigated with surfactant solution was 6.5 times faster than into the roots irrigated with water.ConclusionsThese results prove that water repellency of the rhizosphere of lupins in sandy soils limited the water fluxes into the roots and root rehydration during the first two to three hours after irrigation. This might not always be negative, because it can limit water losses from roots to dry soil and therefore avoid severe root dehydration.