Yellow berry refers to the non-vitreous nature of the wheat kernel. Individual kernels may be vitreous, non-vitreous (yellow berry), or have varying proportions of each (“mottled”). Yellow berry in and of itself represents no defect of the kernel. As in maize, rice, and other cereals, the non-vitreous appearance results from the diffraction of light by minute air spaces and discontinuities in the endosperm. This physical discontinuity of the kernel is highly correlated with protein content, and it is for this reason that there is commercial interest in the trait. In the U.S., the federal standards for wheat differentiate Durum wheat and Hard Red Spring wheat into three subclasses, each based on the percentage of vitreous kernels. Although varieties do differ somewhat in their predisposition to yellow berry, the over-riding cause relates to N fertility and, secondarily, biotic and abiotic stresses on the wheat plant. In general, N applied or available during later grain filling, and yield-reducing stresses (drought, high temperatures) reduce the incidence of yellow berry.
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Henson, J. F., and Waines, W. G. 1983. Nitrogen metabolism and yellow berry of two bread wheat cultivars. Crop Sci. 23:20-22.
Robinson, F. E., and Cudney, D. W. 1979. Nitrate fertilizer timing, irrigation, protein, and yellow berry in durum wheat. Agron. J. 71:304-308.
USDA. 1996. Official United States Standards for Grain. 7 CFR Part 810. U.S. Dep. Agriculture, Grain Inspection, Packers and Stockyards Administration, Federal Grain Inspection Service. September, 1996, USDA-GIPSA-FGIS. U.S. Govt. Printing Office.
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