The impact of global climate change on the freezing tolerance of winter cereals in Western Canada

Abstract

AbstractDue 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.