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Spring freeze events seriously limit the growth, development, and grain yield of winter wheat (Triticum aestivum L.). A 2‐yr field experiment with two contrasting cultivars: XM21 (low‐temperature resistant) and XZ24 (low‐temperature sensitive), was conducted using an air temperature control device designed to allow investigation of the physiological and grain yield responses to spring freeze. The plants were grown in the field and subjected to a 5‐d spring freeze episode (approximately 8°C lower than the ambient temperature) at jointing stage (Zadoks scale 31). Spring freeze significantly decreased gas exchange rates and maximum quantum efficiency of photosystem II in wheat leaves of both cultivars. Under spring freeze, the yield loss was 12 to 14% in XZ24 vs. 5 to 6% in XM21. Greater yield loss in XZ24 coincided with a greater reduction of tiller and spike number in XZ24 than in XM21. Spring freeze occurring …