2021 Volume 90 Issue 1 Pages 72-77
An estimation formula for the grain protein content of the bread wheat cultivar “Setokirara” was constructed by measuring yield and the amount of nitrogen topdressing at anthesis. A data set used for constructing the formula was collected at the fields in Yamaguchi Prefectural Agriculture and Forestry General Technology Center for three years. Multiple regression analysis was used to determine the coefficients of the explanatory variables, and were found to be –4.056×10–3 for yield and 0.517 for nitrogen topdressing. The interaction effect was excluded from the formula because it was not significant. Results demonstrated that the grain protein content of “Setokirara” decreased by 0.406 points as the yield increased by 100 g m–2. Additionally, the grain protein content increased by 0.517 points when 1 g m–2 of nitrogen topdressing was added. The formula was varified using “Setokirara” datasets collected from either the Technology Center (TC) or from a farmer’s fields located in the southern part of Yamaguchi city (FF). The root mean square errors for TC and FF were 1.4% and 2.2%, respectively. The error at FF was larger than that at TC. One reason may be that topdressing application was earlier than anthesis at FF. These results indicate that the formula can estimate grain protein content of “Setokirara” by yield and the amount of nitrogen topdressing at anthesis althogh the error rate may depend on variations in crop management.
