Investigation of the Improvement of the Wheat Endosperm Hardness Assessment Method by Improved Construction of the Grain Cutting Knife

The majority of bread wheat varieties in Croatia belong to the group of falsely hard “red, or winter wheat” characterized by the so-called “marbling” of the grain, i.e. the alternation of glassy and floury zones in the endosperm, which significantly complicates the precision of the standard method of deter-mining the share of glassy grains according to Pohl, ICC method standard 129. Recent research has shown that by improving the construction of the knife (by changing the angle and cutting intensity (the so-called “new knife”), a much clearer “cleaner” cut is obtained, which makes it possible to determine the degree of glassiness of the grain with greater accuracy, especially for the transitional or marmorated endosperms. Guided by this hypothesis, the degree of glassiness of extremely glassy, extremely floury and two transitional (marmorated) types of grains, cut with the “old knife” (standard device) and the “new” knife on the same instrument. The obtained results show that the obtained values for the degree of glassiness do not differ significantly between the old and new knife for extremely glassy and extremely floury wheat, while for marbled grains the measurement values differ significantly between individual evaluators and between different types of endosperm hardness, especially in the area of medium values for grain glassiness (80–20). The conclusion of the research is that when determining the values for grain glassiness of marbling-early hybrids of bread wheat in Croatia, the application of the “new knife” will give significantly more precise and accurate values and facilitate the visual assessment of endosperm glassiness.