Knowing the key hydraulic traits of different genotypes at early seedling stages can potentially provide crucial information and save time for breeding programs. In the current study we investigated: (1) how root, stem and whole plant conductivities are linked to xylem traits, and (2) how the integrated hydraulic system impacts leaf water potential, gas exchange, chlorophyll a fluorescence and the growth of three coffee cultivars (clones of Coffea canephora Pierre ex Froehner cv. Conilon) with known differences in drought tolerance. The Conilon clones CL 14, CL 5 V and CL 109A, classified as tolerant, moderately tolerant, and sensitive to drought respectively, were grown under non-limiting soil-water supply but high atmospheric demand (i.e., high VPD_air). CL 14 and CL 5 V displayed higher root and stem hydraulic conductance and conductivity, and higher whole plant conductivity than CL 109A, and these differences were associated with higher root growth traits. In addition, CL 109A exhibited a non-significant trend towards wider vessels. Collectively, these responses likely contributed to reduce leaf water potential in CL 109A, and in turn, reduced leaf gas exchange, especially during elevated VPD_air. Even when grown under well-watered conditions, the elevated VPD_air observed during this study resulted in key differences in the hydraulic traits between the cultivars corresponding to differences in plant water status, gas exchange, and photochemical activity. Together these results suggest that coffee hydraulic traits, even when grown under non-water stress conditions, can be considered in breeding programs targeting more productive and efficient genotypes under drought and high atmospheric demand.

在苗期早期了解不同基因型的关键水力性状可以潜在地提供关键信息并节省育种计划的时间。在当前的研究中，我们调查了：（1）根，茎和整个植物的电导率如何与木质部性状相关；（2）集成的液压系统如何影响叶片水势，气体交换，叶绿素a荧光和三种咖啡的生长已知的耐旱性差异的栽培品种（Caffeea canephora Pierre ex Froehner cv。Conilon的克隆）。Conilon克隆CL 14，CL 5 V和CL 109A分别被分类为耐性，中度耐性和对干旱敏感，在土壤水供应不受限制但大气需求高（即高VPD）的条件下生长_空气）。与CL 109A相比，CL 14和CL 5 V表现出更高的根和茎水导率和电导率，以及更高的整株电导率，这些差异与更高的根系生长性状有关。另外，CL 109A对较宽的容器显示出不明显的趋势。总体而言，这些响应可能有助于降低CL 109A中的叶片水势，进而减少叶片气体交换，尤其是在VPD_空气升高的情况下。即使在水分充足的条件下生长，VPD_空气也会升高在这项研究中观察到的结果导致了两个品种之间水力性状的关键差异，这与植物水分状况，气体交换和光化学活性的差异相对应。这些结果共同表明，即使在非水分胁迫条件下生长，咖啡的水力性状也可以在针对干旱和高大气需求的更高效和高效基因型的育种计划中加以考虑。