Temperate fruit trees enter a dormant state and resume growth development once cultivar-specific chill requirements (CR) are fulfilled. Sustainable fruit production requires crucial knowledge of the CR of the varieties to predict the adaptability of crops to future climate conditions. Experimental methodologies based on exposing shoots to forcing conditions, and statistical methods based on analysing long-term phenology records, such as Partial Least Square regression (PLS), are commonly used to estimate CR. To demonstrate the importance of unifying methodologies, we compared CR estimations from six approaches that included bud weight increase (30 % and 50 %), different percentages of bud break (30 %, 50 % and 90 %) after forcing conditions, and PLS regression. The CR of four almond and four apricot cultivars were experimentally and statistically determined in Murcia, South-Eastern Spain. Comparisons between approaches revealed that the choice of the method had a significant effect on the estimates. Large variation in CR estimates was found between PLS regression and the experimental methodologies in some late-flowering cultivars. To assess the adaptation potential of a certain cultivar to future climate conditions based on the CR estimates obtained through the different methodologies, we compared the probability of fulfilling cultivar-specific CR's under two global warming scenarios. Projections revealed a marked decreasing trend of chill availability in the region, which is already threatening the cultivation of genotypes with high CR. This study demonstrates that the variability of methodologies used to quantify CR has an important impact on assessing the probability of a successful adaptation. CR obtained by a certain methodology suggest that insufficient chill might be an increasingly common situation for some cultivars, potentially resulting in production risks. Conversely, other methodologies appear to indicate a more favourable performance for the same cultivar. Implementing standardized methods and metrics is essential to ensure more reliable information regarding the prospects for future crop adaptation.

中文翻译：

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确定温带果树寒冷需求的方法差异限制了全球变暖背景下未来种植的指导方针

一旦满足品种特定的寒冷要求（CR），温带果树就会进入休眠状态并恢复生长发育。可持续水果生产需要了解品种 CR 的重要知识，以预测作物对未来气候条件的适应性。基于将芽暴露于强迫条件的实验方法和基于分析长期物候记录的统计方法（例如偏最小二乘回归（PLS））通常用于估计CR。为了证明统一方法的重要性，我们比较了六种方法的 CR 估计，包括芽重增加（30% 和 50%）、强制条件后不同的芽断裂百分比（30%、50% 和 90%）以及 PLS 回归。在西班牙东南部穆尔西亚，通过实验和统计确定了四个杏仁和四个杏品种的 CR。方法之间的比较表明，方法的选择对估计有显着影响。在一些晚花品种中，PLS 回归和实验方法之间的 CR 估计值存在很大差异。为了根据通过不同方法获得的 CR 估计来评估某个品种对未来气候条件的适应潜力，我们比较了在两种全球变暖情景下实现特定品种 CR 的概率。预测显示该地区的冷量呈显着下降趋势，这已经威胁到高 CR 基因型的种植。这项研究表明，用于量化 CR 的方法的可变性对评估成功适应的可能性具有重要影响。通过某种方法获得的CR表明，对于某些品种来说，冷藏不足可能是越来越常见的情况，可能导致生产风险。相反，其他方法似乎表明同一品种的性能更佳。实施标准化方法和指标对于确保有关未来作物适应前景的更可靠信息至关重要。