Abstract：
Fundamental questions in bud dormancy remain, including what temperatures fulfill dormancy requirements (i.e., chill accumulation). Recent studies demonstrate freezing temperatures promote chill accumulation and cold hardiness influences time to budbreak - the phenotype used for dormancy evaluations. Here we evaluated bud cold hardiness (CH) and budbreak responses of grapevines (Vitis hybrids) throughout chill accumulation under three treatments: constant (5 °C), fluctuating (-3.5 to 6.5 °C daily), and field conditions (Madison, WI, USA). Chill treatments experiencing lower temperatures promoted greater gains in cold hardiness (CHfield>CHfluctuating>CHconstant). All treatments decreased observed time to budbreak with increased chill accumulation. However, perceived treatment effectiveness changed when time to budbreak was adjusted to remove cold acclimation effects. Among three classic chill models (North Carolina, Utah, and Dynamic), none were able to correctly describe adjusted time to budbreak responses to chill accumulation. Thus, a new model is proposed that expands the range of chill accumulation temperatures to include freezing temperatures and enhances chill accumulation under fluctuating temperature conditions. Most importantly, our analysis demonstrates adjustments for uneven acclimation change the perceived effectiveness of chill treatments. Therefore, future work in bud dormancy would benefit from simultaneously evaluating cold hardiness.
摘要：
芽休眠的基本问题仍然存在，包括什么温度满足休眠要求(即，寒意积累)。最近的研究表明，冻结温度会促进寒冷的积累，而抗寒性会影响萌芽时间-用于休眠评估的表型。在这里，我们评估了在三种处理下，葡萄树（Vitishybrids）在整个寒冷积累过程中的芽抗寒性（CH）和萌芽反应：恒定（5°C），波动（每天-3.5至6.5°C），和现场条件(麦迪逊，WI,美国）。经历较低温度的冷却处理促进了抗寒性的更大增益(CHfield>CHflowating>CHconstant)。所有处理都减少了观察到的萌芽时间，并增加了寒意积累。然而,当调整萌芽时间以消除冷适应效应时，感知的治疗效果会发生变化。在三种经典的寒战模型中(北卡罗来纳州，犹他州,和动态)，没有人能够正确描述对寒意积累的萌芽反应的调整时间。因此，提出了一种新的模型，该模型扩大了积冷温度的范围，使其包括冻结温度，并在波动的温度条件下增强了积冷。最重要的是,我们的分析表明,对不均匀适应的调整改变了寒战治疗的感知有效性.因此,芽休眠的未来工作将受益于同时评估抗寒性。
