Oxygen dynamics in submerged rice (Oryza sativa)
Oxygen dynamics in submerged rice (Oryza sativa)
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DOI：
10.1111/j.1469-8137.2007.02364.x
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发表时间：
2008-01-01
期刊：
影响因子：
9.4
通讯作者：
Pedersen, O.
中科院分区：
文献类型：
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作者：
Colmer, T. D.;Pedersen, O.
植物完全浸没可防止 O-2 和 CO2 与空气直接交换。水下光合作用会导致水下植物的 O-2 供应发生显着的昼夜变化。尚未直接测量沉水水稻 (Oryza sativa) 的 pO(2) 动态，但在早期研究中，根部径向 O-2 损失在芽照明后出现初始峰值。使用 O-2 微电极在光照和黑暗期间监测沉水水稻芽和根的 O-2 动态。还测量了组织糖浓度。在淹没水稻芽的光照下，pO(2) 迅速增加，然后略微下降到新的准稳态。初始峰首先在芽中出现，然后在根中出现，并且当向培养基中添加20 mol m(-3) 葡萄糖以确保根中的底物供应时仍然观察到初始峰。在光照后新的准稳定状态下，鞘部的 pO(2) 比黑暗中高一个数量级，根部的 pO(2) 也有所提高。淹没水稻光照后 pO(2) 的初始峰值可能是由于黑暗期间积累的 CO2 所推动的高初始净光合作用速率所致。然而，由于淹没水稻中的糖分随着时间的推移而下降，呼吸作用的底物限制也可能导致长时间淹没后 pO(2) 的早晨峰值。
Complete submergence of plants prevents direct O-2 and CO2 exchange with air. Underwater photosynthesis can result in marked diurnal changes in O-2 supply to submerged plants. Dynamics in pO(2) had not been measured directly for submerged rice (Oryza sativa), but in an earlier study, radial O-2 loss from roots showed an initial peak following shoot illumination.O-2 dynamics in shoots and roots of submerged rice were monitored during light and dark periods, using O-2 microelectrodes. Tissue sugar concentrations were also measured.On illumination of shoots of submerged rice, pO(2) increased rapidly and then declined slightly to a new quasi-steady state. An initial peak was evident first in the shoots and then in the roots, and was still observed when 20 mol m(-3) glucose was added to the medium to ensure substrate supply in roots. At the new quasi-steady state following illumination, sheath pO(2) was one order of magnitude higher than in darkness, enhancing also pO(2) in roots.The initial peak in pO(2) following illumination of submerged rice was likely to result from high initial rates of net photosynthesis, fuelled by CO2 accumulated during the dark period. Nevertheless, since sugars decline with time in submerged rice, substrate limitation of respiration could also contribute to morning peaks in pO(2) after longer periods of submergence.