Relationship Between Crown Moisture Content and Killing Temperature for Three Wheat and Three Barley Cultivars1

Abstract

A quantitative investigation of the relationship between freeze‐damaged plant crowns and the percent moisture of the crowns was conducted. ‘Wong,’ ‘Hudson,’ and ‘Dicktoo’ barleys (Hordeum vulgare L.) and ‘Genesee,’ ‘Illinois 59‐884’ (CI 14023), and ‘Redcoat’ wheats (Triticum aestivum L.) were the cultivars studied. Artificial freezing tests, over a temperature range of —18 to —7 C and over a range of adjusted plant crown moisture percentages of 55 to 75%, were used. Crown damage was assessed as a root regrowth rating on an arbitrary scale of 0 to 9. Equations were obtained for each cultivar relating root regrowth to crown moisture and killing temperature. Predicted root regrowth was plotted against crown moisture and killing temperature as curves representing several levels of survival. The close relationship which exists between moisture content and freezing injury at specific temperatures was clearly demonstrated. Dicktoo barley and Illinois 59‐884 wheat were the cultivars most resistant to freeze‐damage. Macroscopic pictures of freeze‐damaged plant crowns are included.