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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 vulgareL.) and ‘Genesee,’ ‘Illinois 59‐884’ (CI 14023), and ‘Redcoat’ wheats (Triticum aestivumL.) 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.

The genotype‐environmental interaction of test weight and its components in Eastern soft winter wheat, Triticum aestivumL. em ‘Thell,’ was studied at seven locations in 2 years. Significant effects of location and years for test weight indicate that breeders should include a sample of years and locations when selecting for this character. By removing the differential effects of density, an environmental characteristic, from test weight and dealing only with packing efficiency, a varietal characteristic, a definite gain in genetic variance was obtained. Although test weight and kernel weight under different environments were highly correlated, a covariance analysis demonstrated no genetic correlation between them. This suggests that there are no genes in common controlling test weight and kernel weight in the varieties studied. Utilizing a combined regression analysis to examine genotype stability of test weight, cultivars and advanced breeding lines that had a significant interaction with the nursery means over different environments were identified. These lines were relatively indifferent to environmental variation and always had good test‐weight performance. The analysis also identified genotypes with average sensitivity and lines with extreme or undesirable sensitivity.

Test weight is defined as the weight of grain that fills a given volume. It is the product of kernel density and volume of grain occupying the container. The latter component, when expressed as percentage of the volume of the container, is referred to as packing efficiency and was shown to be a cultivar characteristic. Of the two components packing efficiency has a greater effect on test weight when comparing soft winter wheats (Triticum aestivumL. em Thell). There was a negative correlation between test weight and the kernel length‐width ratio (kernel shape). When the length‐width ratio remained constant, there was no increase in test weight when kernel volume increased. Kernel width was correlated more than length with kernel volume. Test weight and flour yield were not correlated within or among cultivars. Kernel protein was related to kernel size within cultivars.

The activity of freezing kinetics inhibitors was characterized by a visual rating technique for several wheat (Triticum aestivumL.) cultivars. The procedure allowed a single test of a cultivar with a minimum of 13 g of seed, and 10 tests per day with the equipment available. Comparisons between several replications of kinetic inhibitor ratings and cultivar survival of high‐intensity freezing showed expected relationships. The activity of kinetic inhibitors from some cultivars was commensurate with survival ability. However, other cultivars exhibited better kinetic inhibitor activity than indicated by their survival rating. The ability to identify cultivars with high activity with no confounding effect by plant weaknesses in other areas that can affect survival, is a distinct advantage of this test. All wheat cultivars tested had lower ratings than ‘Rosen’ rye, the standard for the maximum rating. A large number of cultivars with varied genetic backgrounds are now being screened for improved kinetic inhibitor activity using this technique. As an initial inquiry leading to the screening technique, the validity of using seed as the polysaccharide source in the kinetic inhibitor tests was substantiated by hydrolysis and chromatography. Monosaccharide components were similar for polysaccharides extracted from crown tissues, the important area of freezing resistance, and from seed tissue. Purifying the polysaccharide extracts has proved difficult. In the best preparations, no compositional differences were seen between those polysaccharides exhibiting activity as kinetic inhibitors and those showing inactivity.