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首页> 外文期刊>Journal of Experimental Botany >Patterns of nocturnal rehydration in root tissues of Vaccinium corymbosum L. under severe drought conditions.
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Patterns of nocturnal rehydration in root tissues of Vaccinium corymbosum L. under severe drought conditions.

机译：严重干旱条件下越桔根组织夜间补液的规律

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摘要

Although roots in dry soil layers are commonly rehydrated by internal hydraulic redistribution during the nocturnal period, patterns of tissue rehydration are poorly understood. Rates of nocturnal rehydration were examined in roots of different orders in Vaccinium corymbosum L. 'Bluecrop' (Northern highbush blueberry) grown in a split-pot system with one set of roots in relatively moist soil and the other set of roots in dry soil. Vaccinium is noted for a highly branched and extremely fine root system. It is hypothesized that nocturnal root tissue rehydration would be slow, especially in the distal root orders because of their greater hydraulic constraints (smaller vessel diameters and fewer number of vessels). Vaccinium root hydraulic properties delayed internal water movement. Even when water was readily available to roots in the wet soil and transpiration was minimal, it took a whole night-time period of 12 h for the distal finest roots (1st to 4th order) under dry soil conditions to reach the same water potentials as fine roots in moist soil (1st to 4th order). Even though roots under dry soil equilibrated with roots in moist soil, the equilibrium point reached before sunrise was about -1.2 MPa, indicating that tissues were not fully rehydrated. Using a single-branch root model, it was estimated that individual roots exhibiting the lowest water potentials in dry soil were 1st order roots (distal finest roots of the root system). However, considered at the branch level, root orders with the highest hydraulic resistances corresponded to the lowest orders of the permanent root system (3rd-, 4th-, and 5th-order roots), thus indicating possible locations of hydraulic safety control in the root system of this species.
机译：尽管在夜间，干燥土壤层中的根通常通过内部水力重新分配而补水，但对组织补水的方式知之甚少。夜芽水化率在Vaccinium corymbosum L.中以不同顺序的根进行了检查。“ Bluecrop”（北高丛蓝莓）在分锅系统中生长，其中一组根系在较湿的土壤中，另一组根在干土中。牛痘被认为是高度分支且极细的根系。据推测，夜间根部组织补液会很慢，尤其是在远侧根部，因为它们的水力约束更大（较小的血管直径和较少的血管数量）。牛痘根的水力特性延迟了内部水分的流动。即使在湿土壤中根系容易获得水分并且蒸腾作用很小的情况下，在干燥土壤条件下，最细末梢的根部（第1至第4阶）也要花整整12个小时的夜间时间才能达到与细根在潮湿的土壤中（第1到第4阶）。即使干燥土壤下的根与潮湿土壤中的根平衡，日出前达到的平衡点仍约为-1.2 MPa，这表明组织尚未充分补水。使用单分支根模型，估计在干燥土壤中表现出最低水势的单个根为一阶根（根系的远端细根）。但是，从分支级别考虑，具有最高水力阻力的根序对应于永久性根系的最低序（三阶，四阶和五阶根），因此表明了在根部进行水力安全控制的可能位置该物种的系统。

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