At the genus and species level, variation in root anatomy and architecture may interact to affect strategies of drought avoidance. To investigate this idea, root anatomy and architecture of the drought‐sensitive common bean (Phaseolus vulgaris) and drought‐adapted tepary bean (Phaseolus acutifolius) were analyzed in relation to water use under terminal drought. Intraspecific variation for metaxylem anatomy and axial conductance was found in the roots of both species. Genotypes with high‐conductance root metaxylem phenotypes acquired and transpired more water per unit leaf area, shoot mass, and root mass than genotypes with low‐conductance metaxylem phenotypes. Interspecific variation in root architecture and root depth was observed where P. acutifolius has a deeper distribution of root length than P. vulgaris. In the deeper‐rooted P. acutifolius, genotypes with high root conductance were better able to exploit deep soil water than genotypes with low root axial conductance. Contrastingly, in the shallower‐rooted P. vulgaris, genotypes with low root axial conductance had improved water status through conservation of soil moisture for sustained water capture later in the season. These results indicate that metaxylem morphology interacts with root system depth to determine a strategy of drought avoidance and illustrate synergism among architectural and anatomical phenotypes for root function.

中文翻译：

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根生木质部和建筑表型整合在一起，调节干旱胁迫下的用水。

在属和种的水平上，根部解剖结构和结构的变化可能相互作用，从而影响避免干旱的策略。为了研究这一思想，分析了干旱敏感的普通豆（菜豆）和适应干旱的三元豆（菜豆）的根部解剖结构和结构，并探讨了干旱条件下的水分利用情况。在两个物种的根中都发现了木质部解剖学和轴传导的种内变异。高传导根部木质部表型的基因型比低传导性根部木质部表型的基因型每单位叶面积，枝条质量和根部质量获得的水分更多。观察到P. acutifolius的根系结构和根深存在种间差异与寻常假单胞菌相比，根长分布更深。在根深厚的P. acutifolius中，具有高根电导率的基因型比具有低根轴电导率的基因型更能利用深层土壤水分。相反，在根部较浅的寻常型百日咳中，低根轴电导率的基因型通过保持土壤水分以改善本季后期的持水量而改善了水分状况。这些结果表明，根外根的形态与根系深度相互作用，从而确定了避免干旱的策略，并说明了根系功能在建筑和解剖表型之间的协同作用。