Freeze tolerance is a complex agronomic trait that is difficult to evaluate in the field because of year‐to‐year variation in weather. Discovering plant characteristics closely related to freeze tolerance would enable more effective selection for this important trait. To explore possible physiological mechanisms and search for useful characteristics related to freeze tolerance in winter barley, we conducted field and growth chamber experiments with seven freeze‐tolerant and seven freeze‐susceptible genotypes that exhibited contrasting winter survival in preliminary field screenings. In a 2‐year field experiment, malondialdehyde, proline and water‐soluble carbohydrate concentrations were measured during cold acclimation and deacclimation to investigate differences in osmoregulation and membrane stability between freeze‐tolerant and freeze‐sensitive genotypes. All parameters varied by sampling year, and significant differences between freeze tolerance groups were found mainly during cold deacclimation in the spring. In growth chamber experiments, the size of xylem vessels and stomates was measured with and without cold acclimation. Freeze‐tolerant genotypes had smaller xylem vessels and stomates than freeze‐sensitive genotypes with and without cold acclimation, and small stomatal length was associated with a small xylem vessel area. Thus, it may be possible to improve freeze tolerance in winter barley by selecting smaller xylem and stomate cells. This study also validated germplasms of winter barley with differential freeze tolerance for future projects on breeding for improving winter hardiness and on plant physiology and genetics in response to freezing stress.

中文翻译：

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与冬大麦耐冻性相关的小气孔和木质部导管


耐冻性是一种复杂的农艺性状，由于天气逐年变化，很难在田间进行评估。发现与耐冻性密切相关的植物特征将使对这一重要性状的更有效选择成为可能。为了探索可能的生理机制并寻找与冬大麦耐冻性相关的有用特征，我们对七种耐冻基因型和七种冻敏感基因型进行了田间和生长室实验，这些基因型在初步田间筛选中表现出对比鲜明的冬季存活率。在一项为期两年的现场实验中，测量了冷驯化和去驯化过程中的丙二醛、脯氨酸和水溶性碳水化合物浓度，以研究耐冻基因型和冻敏感基因型之间渗透调节和膜稳定性的差异。所有参数随采样年份的不同而变化，耐冻组之间的显着差异主要出现在春季冷驯化过程中。在生长室实验中，在冷驯化和不冷驯化的情况下测量木质部导管和气孔的尺寸。在有或没有冷驯化的情况下，耐冻基因型比冷冻敏感基因型具有更小的木质部导管和气孔，并且较小的气孔长度与较小的木质部导管面积相关。因此，有可能通过选择较小的木质部和气孔细胞来提高冬大麦的抗冻性。这项研究还验证了具有差异抗冻性的冬大麦种质，用于未来提高抗寒性的育种项目以及应对冰冻胁迫的植物生理学和遗传学项目。