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首页> 外文期刊>Plant and Soil >Oxygen distribution and movement, respiration and nutrient loading in banana roots (Musa spp. L.) subjected to aerated and oxygen-depleted environments
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Oxygen distribution and movement, respiration and nutrient loading in banana roots (Musa spp. L.) subjected to aerated and oxygen-depleted environments

机译：曝气和缺氧环境下香蕉根（Musa spp。L.）的氧气分布和运动，呼吸和养分含量

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Excessive soil wetness is a common feature where bananas (Musa spp.) evolved. Under O2 deficiency, a property of wet soils, root growth and functions will be influenced by the respiratory demand for O2 in root tissues, the transport of O2 from the shoot to root and the supply of O2 from the medium. In laboratory experiments with nodal roots of banana, we examined how these features influenced the longitudinal and radial distributions of O2 within roots, radial O2 loss, solute accumulation in the xylem, root hydraulic conductivity, root elongation and root tip survival. In aerated roots, the stele respired about 6 times faster than the cortex on a volume basis. Respiratory O2 consumption decreased substantially with distance from the root apex and at 300–500 mm it was 80% lower than at the apex. Respiration of lateral roots constituted a sink for O2 supplied via aerenchyma, and reduced O2 flow towards the tip of the supporting root. Stelar anoxia could be induced either by lowering the O2 partial pressure in the bathing medium from 21 to 4 kPa (excised roots) or, in the case of intact roots, by reducing the O2 concentration around the shoot. The root hair zone sometimes extended to 1.0 mm from the root surface and contributed up to a 60% drop in O2 concentration from a free-flowing aerated solution to the root surface. There was a steep decline in O2 concentration across the epidermal-hypodermal cylinder and some evidence of a decline in the O2 permeability of the epidermal-hypodermal cylinder with increasing distance from the root apex. The differences in O2 concentration between cortex and stele were smaller than reported for maize and possibly indicated a substantial transfer rate of dissolved O2 from cortex to stele in banana, mediated by a convective water flow component. An O2 partial pressure of 4 kPa in the medium reduced net nutrient transfer into the vascular tissue in the stele within 1 or 2 h. Hypoxia also caused a temporary decrease in radial root hydraulic conductivity by an order of magnitude. In O2 deficient environments, the stele would be among the first tissues to suffer anoxia and O2 consumption within the root hair zone might be a major contributor to root anoxia/hypoxia in banana growing in temporarily flooded soils.
机译：过度潮湿是香蕉（Musa spp。）进化的一个共同特征。在O2 缺乏的情况下，湿润土壤的特性，根的生长和功能将受到根组织中O2 的呼吸需求，O2 从枝条到根的运输以及土壤中根系的影响。从介质中供应氧气。在香蕉节根的实验室实验中，我们研究了这些特征如何影响根中O2 的纵向和径向分布，径向O2 损失，木质部中的溶质积累，根部水力传导率，根伸长和根尖存活。在充气的根中，石碑的呼吸量比皮质的快约6倍。呼吸氧气的消耗量随着与根尖距离的增加而显着降低，并且在300–500 mm时比根尖低80％。侧根的呼吸构成了通过气孔供应的O2 的汇，并减少了向支撑根尖端的O2 流动。可以通过将沐浴液中的O2 分压从21 kPa降低到4 kPa（已切除的根）来诱导Steaf缺氧，对于完整的根，则可以通过降低枝条周围的O2 浓度来诱导。根毛区域有时会延伸到距根表面1.0毫米处，并导致从自由流动的充气溶液到根表面的O2浓度降低60％。表皮-次表皮圆柱体之间的O2 浓度急剧下降，并且有证据表明表皮-次表皮圆柱体的O2 渗透性随距根尖距离的增加而降低。皮层和石碑之间的O2 浓度差异小于玉米的报道，可能表明溶解的O2 在香蕉中由对流水流成分介导的从皮层到石碑的大量转移速率。培养基中4 kPa的O2分压会在1或2小时内减少净营养素转移到碑石的血管组织中。低氧还导致径向根部水力传导率暂时降低一个数量级。在O2缺乏的环境中，石碑将是最早遭受缺氧的组织之一，而在根毛区内消耗O2可能是造成临时淹水土壤中香蕉根缺氧/缺氧的主要原因。

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