Abstract Phenological traits are crucial for understanding adaptation to climate change due to their genetic control and association with abiotic factors. However, few data on phenology patterns are available for South American Nothofagus species, in particular for Nothofagus alpina, a key species of the temperate forests of Patagonia. Therefore, our aim was to analyze the variation among and within natural populations of N. alpina in two phenological traits (bud burst and foliar senescence), in growing season length and in relative growth height. We registered phenology in 65 open pollinated families of eight Argentinean natural populations installed in a common garden trial. Apical buds and foliar senescence were observed every three days in 6-year-old plants and again three years later in the same plants (N = 373). Day of the year until bud burst (DOY) and until the beginning (DOY10) and the end (DOY90) of foliar senescence were measured. Height was measured twice in a year in order to calculate the annual growth in both seasons. Growing degree days (GDD) and chilling hours (CH) until bud burst were also calculated, with two possible basal temperatures (5 °C and 7 °C) to evaluate their role in DOY. Significant differences among populations and years in DOY and growing season length were found using a linear mixed model (LMM), with the family factor explaining around 30% and 12% of the total variance respectively. The LMM for foliar senescence (DOY10 and DOY90) and the relative growth height (RGH) showed significant differences between years but not among populations. The family factor was significant for foliar senescence, although it only explained a small part of the total variance (DOY10: 4%; DOY90: 2%) and was not significant for relative growth height. A tight relationship between GDD and CH with DOY was found, and LMM showed significant differences among populations and years for both variables. The correlation between the altitude of natural populations and the mean DOY and GDD was high and positive. Our results reveal (i) the genetic control of bud burst and foliar senescence, and phenotypic plasticity of all analyzed traits, (ii) that GDD and CH are implicated in the DOY, and (iii) that altitude is probably conditioning thermal requirement of bud burst. This information suggests good perspectives to face the climate change scenario and highlight the importance of selecting appropriate populations and families for domestication and breeding of N. alpina at particular sites.

中文翻译：

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在一项普通花园试验中进行的为期两年的评估揭示了南美 Nothofagus 自然种群之间和内部的物候差异

摘要 由于遗传控制和与非生物因素的关联，物候性状对于理解对气候变化的适应至关重要。然而，关于南美 Nothofagus 物种的物候模式数据很少，尤其是 Nothofagus alpina，这是巴塔哥尼亚温带森林的一个关键物种。因此，我们的目的是分析高山猪笼草自然种群之间和内部在生长季节长度和相对生长高度两个物候性状（芽爆裂和叶面衰老）方面的变化。我们在一个共同的花园试验中对 8 个阿根廷自然种群的 65 个开放授粉家庭进行了物候学登记。在 6 年生植物中每三天观察一次顶芽和叶面衰老，三年后在相同植物中再次观察（N = 373）。测量了一年中的某一天直到芽破 (DOY) 和直到叶衰老的开始 (DOY10) 和结束 (DOY90)。每年测量两次身高，以计算两个季节的年增长率。还计算了生长期 (GDD) 和萌芽前的冷却时间 (CH)，并使用两种可能的基础温度 (5 °C 和 7 °C) 来评估它们在 DOY 中的作用。使用线性混合模型 (LMM) 发现 DOY 和生长季节长度的种群和年份之间存在显着差异，家庭因素分别解释了总方差的 30% 和 12%。叶片衰老的 LMM（DOY10 和 DOY90）和相对生长高度（RGH）在年份之间显示出显着差异，但在种群之间没有显着差异。家族因素对叶面衰老显着，尽管它只解释了总方差的一小部分（DOY10：4%；DOY90：2%）并且对相对生长高度不显着。发现 GDD 和 CH 与 DOY 之间存在紧密关系，并且 LMM 显示这两个变量在人口和年份之间存在显着差异。自然种群海拔高度与平均 DOY 和 GDD 之间的相关性较高且呈正相关。我们的结果揭示 (i) 芽破和叶衰老的遗传控制，以及所有分析性状的表型可塑性，(ii) GDD 和 CH 与 DOY 相关，以及 (iii) 海拔高度可能调节芽的热需求爆裂。这些信息为应对气候变化情景提供了良好的前景，并强调了选择合适的种群和家庭来驯化和繁殖猪笼草的重要性。