Abstract
Annual variation of wheat flour whiteness was examined to establish cultivation techniques for producing good quality wheat with high (superior) and stable flour whiteness. The degree of flour whiteness increased as the bulk density of grains and the maximum viscosity (of the flour) increased and the protein content and precipitation during late stage of ripening decreased. Especially, the correlation of flour whiteness with the bulk density of grains was high, with the highest correlation coefficient. There was a negative relationship between the bulk density of grains and precipitation during the late ripening stage (1-15 days before maturity stage). These results indicate the possibility of using the bulk density of grains as an index of flour whiteness and rain damage. The degree of flour whiteness was influenced the most by precipitation 3 to 6 days before the maturity stage. Judging from the above results, improvement of the tolerance to the precipitation during the late ripening stage is most important for stable production of wheat flour with superior (high) whiteness. The selection of the cultivars whose quality was little damaged by the precipitation during the late ripening stage, and early sowing that allow harvest in May with little precipitation, may be effective for producing good quality wheat with superior (high) and stable flour whiteness.
