Abstract The objective of this study was to investigate the dormancy dynamics of ‘Tannat’ grapes in warm-winter climate conditions, as well as correlating it to chill and heat accumulation. Single-nodes of 1-year-old canes were sampled throughout fall-winter, corresponding to different chill accumulation periods, and placed in growth chamber as means to evaluate the percentage of budburst, the time of 50% budburst (DD50), the time (days) to reach DD50, maximum budburst (MB), and average time to budburst (ATB). For each sampling date, chill accumulation was calculated according to several models in order to detect the most suitable for our climatic conditions. Heat accumulation, expressed as growing degree hours (GDH) was also calculated in order to predict budburst in the field from the completion of endodormancy and maximum budburst. Our results show that the single-node test is effective to represent the dormancy dynamics of ‘Tannat’ grapes in warm-winter conditions. Besides, the DD50 is a valid concept to determine endodormancy completion, which was fulfilled with approximately 100 chill hours below 7.2 °C (CH7). Even though the CH7 was the most consistent model, our results suggest that endodormancy is induced by temperatures greater than 7.2 °C in late summer/early fall. The growing degree hours (GDH) accumulated from the end of endodormancy and maximum budburst is fairly accurate to estimate actual budburst in the field. Chill accumulation is inversely correlated with time to reach DD50 and ATB, i.e., as chill accumulation increases time to reach DD50 and ATB decreases.

中文翻译：

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'Tannat' 葡萄在暖冬气候条件下的休眠动态

摘要 本研究的目的是调查‘Tannat’葡萄在暖冬气候条件下的休眠动态，并将其与寒冷和热量积累相关联。1年生甘蔗单节在整个秋冬季取样，对应不同的寒气积累期，放入生长室作为评价萌芽率、50%萌芽时间（DD50）、时间(天) 达到 DD50、最大萌芽 (MB) 和平均萌芽时间 (ATB)。对于每个采样日期，根据多个模型计算冷量累积，以检测最适合我们气候条件的数据。还计算了热量积累，表示为生长期（GDH），以便从内休眠的完成和最大的萌芽来预测田间的萌芽。我们的结果表明，单节点测试可以有效地代表 'Tannat' 葡萄在暖冬条件下的休眠动态。此外，DD50 是确定内休眠完成的有效概念，在低于 7.2 °C (CH7) 的情况下大约 100 小时的冷却时间完成。尽管 CH7 是最一致的模型，但我们的结果表明，夏末/秋初温度高于 7.2 °C 会诱导内眠。从内休眠结束和最大萌芽开始累积的生长期（GDH）对于估计田间的实际萌芽是相当准确的。冷量积累与达到 DD50 和 ATB 的时间成反比，即，随着冷量积累增加达到 DD50 的时间，ATB 减少。