Due to global climate change in Western Canada, winter cereals will be exposed to a higher frequency of winter thaws which will increase crown water and thereby reduce freezing tolerance. Cold‐acclimated winter wheat (Triticum aestivum L.) and fall rye (Secale cereale L.) were held at −4°C under a snow cover for up to 120 days and periodically subjected to a dry or wet thaw for 3 days. Freezing tolerance was monitored by either the conventional freezing test (LT₅₀) or the durational freeze test (LD₅₀). There was a gradual loss in LT₅₀ and LD₅₀ in crowns held at −4°C, with the greatest loss after 120 days. The LT₅₀ test could only identify species differences in freezing tolerance whereas LD₅₀ identified cultivar‐specific differences. Rehardened plants previously subjected to a 4°C dry thaw regained an LT₅₀ comparable to non‐thawed plants. Whereas plants exposed to a wet thaw could only partially reharden. The more freezing tolerant fall rye cultivars maintained a lower LT₅₀ under thawing and rehardening conditions as compared with winter wheat. A short winter thaw dramatically reduced crown freezing tolerance. The selection of superior germplasm to tolerate warming winter conditions is an important goal for future winter wheat breeding efforts.

中文翻译：

---

全球气候变化对加拿大西部冬季谷物的耐冻性的影响

由于加拿大西部地区的全球气候变化，冬季谷物将经历更高频率的冬季解冻，这将增加冠冕水分，从而降低耐冻性。将冷驯化的冬小麦（Triticum aestivum L.）和秋黑麦（Secale graine L.）在-4°C下的积雪下保持长达120天，并定期进行干或湿解冻3天。通过常规冷冻测试（LT ₅₀）或持续冷冻测试（LD ₅₀）监控冷冻耐受性。保持在−4°C的表冠中LT ₅₀和LD ₅₀逐渐损失，在120天后损失最大。LT ₅₀试验仅能鉴定出抗寒性的物种差异，而LD _50则能鉴定出特定品种的差异。之前经受过4°C干融解处理的再硬化植物的LT ₅₀与未融化的植物相当。暴露于湿融化条件下的植物只能部分重新硬化。与冬小麦相比，更耐寒的黑麦品种在解冻和再硬化条件下保持较低的LT ₅₀。短暂的冬季解冻大大降低了表冠的冷冻耐受性。选择优良的种质以耐受冬季变暖是今后冬小麦育种工作的重要目标。