The critical nitrogen (N) dilution curve (CNDC) (Nc = A₁W^-A2) and the N nutrition index (NNI) have shown to be a robust diagnostic tool to assess crop N status. Several CNDCs were established for potatoes (Solanum tuberosum L.) in various conditions. However, it is difficult to know if these different CNDCs reflect a true variability across genotype × environment × management (G×E × M) scenarios, or are rather linked to estimation errors. Therefore, the aims of this study were to (i) estimate and compare CNDCs via a Bayesian statistical approach for different G×E × M scenarios in tropical environments and (ii) assess the uncertainty in the relationship between tuber yield and NNI. Field experiments were conducted in three site-years (SYs) in the southeastern region of Brazil. Treatments consisted of two potato cultivars (Agata and Electra) and five N fertilization managements [differing in the N rates (0 −320 kg N ha^-1) and/or application timings]. Based on 95% credibility intervals, we found no significant differences between CNDCs across G×E × M scenarios assessed and thus derived a single generic CNDC for both cultivars and all SYs defined by Nc = 3.86 W^-0.34. This global CNDC was used to compute NNI and discriminate tuber yields obtained under N-limiting and non-N-limiting conditions. An uncertainty analysis revealed that critical NNI threshold values for the tuber yield response to N management were not statistically different among G×E × M scenarios. Therefore, these results support the use of a unique CNDC for estimating the N status (NNI) of potato crop in tropical environments. We found no evidence of the need for SY- or cultivar-specific CNDCs. Future studies should evaluate N dilution curves and NNI for potato across different production environments worldwide.

临界氮 (N) 稀释曲线 (CNDC) ( Nc = A ₁ W ^-A2 ) 和氮营养指数 (NNI) 已被证明是评估作物氮状况的可靠诊断工具。为马铃薯（马铃薯）建立了几个 CNDCL.) 在各种条件下。然而，很难知道这些不同的 CNDC 是否反映了跨基因型 × 环境 × 管理 (G×E × M) 情景的真实变异性，或者与估计误差有关。因此，本研究的目的是（i）通过贝叶斯统计方法估计和比较热带环境中不同 G×E×M 情景的 CNDC，以及（ii）评估块茎产量与 NNI 之间关系的不确定性。田间试验在巴西东南部地区以三个地点年 (SYs) 进行。处理包括两种马铃薯品种（Agata 和 Electra）和五种 N 施肥管理[不同的 N 比率（0 -320 kg N ha ^-1) 和/或申请时间]。基于 95% 的可信区间，我们发现 CNDC 在所评估的 G×E×M 情景中没有显着差异，因此为两个品种和由Nc =  3.86  W ^{- 0.34}定义的所有 SY 推导出一个单一的通用 CNDC. 该全球 CNDC 用于计算 NNI 并区分在 N 限制和非 N 限制条件下获得的块茎产量。不确定性分析表明，在 G×E×M 情景中，块茎产量对 N 管理响应的关键 NNI 阈值没有统计学差异。因此，这些结果支持使用独特的 CNDC 估计热带环境中马铃薯作物的 N 状态 (NNI)。我们没有发现需要 SY 或品种特异性 CNDC 的证据。未来的研究应评估全球不同生产环境中马铃薯的 N 稀释曲线和 NNI。