The impact of global climate change on the freezing tolerance of winter cereals in Western Canada
Ian R. Willick, Karen Tanino, Lawrence V. Gusta
Abstract
Abstract 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 (LT 50 ) or the durational freeze test (LD 50 ). There was a gradual loss in LT 50 and LD 50 in crowns held at −4°C, with the greatest loss after 120 days. The LT 50 test could only identify species differences in freezing tolerance whereas LD 50 identified cultivar‐specific differences. Rehardened plants previously subjected to a 4°C dry thaw regained an LT 50 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 LT 50 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.