Department of Plant and Agroecosystem Sciences, University of Wisconsin-Madison, Madison, WI 53706, USA.
J Exp Bot. 2024 Oct 16;75(19):6182-6193. doi: 10.1093/jxb/erae287.
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 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 (field>fluctuating>constant). 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 was 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 that adjustments for uneven acclimation change the perceived effectiveness of chill treatments. Therefore, future work in bud dormancy would benefit from simultaneously evaluating cold hardiness.
休眠期的基本问题依然存在，包括什么温度能满足休眠要求（即需冷量）。最近的研究表明，低温促进需冷量的积累，而冷胁迫耐性会影响芽休眠的解除时间——休眠评价的表型。在这里，我们在三种处理条件下（恒定温度为 5°C，波动温度为-3.5 至 6.5°C 每天，田间条件）对葡萄（杂交品种）的芽冷胁迫耐性和芽休眠解除响应进行了评估：恒定温度、波动温度和田间温度。经历低温的需冷量处理会促进冷胁迫耐性的更大提升（田间温度>波动温度>恒定温度）。所有处理都随着需冷量的增加而减少了芽休眠的观察时间。然而，当将芽休眠时间调整以去除冷驯化效应时，处理效果的感知发生了变化。在三种经典需冷量模型（北卡罗来纳州、犹他州和动态模型）中，没有一个能正确描述调整后对需冷量积累的芽休眠解除响应。因此，提出了一种新的模型，该模型扩展了需冷量积累温度范围，包括低温，并增强了波动温度条件下的需冷量积累。最重要的是，我们的分析表明，对不均匀驯化的调整改变了对需冷量处理效果的感知。因此，未来休眠期的研究将受益于同时评估冷胁迫耐性。
