Inter-annual correlation for protein content and weight per unit volume in wheat
1930
Treloar, A.E. | Harris, J.A.
The possibility of the prediction of the quality (protein content, weight per unit volume, quality index, etc.) of the wheat crop of the individual districts of a large geographic area must depend on the existence of significant correlations between these variables in different years. Statistical analysis of the data for average weight per hectolitre, protein content, and quality index of the Roumanian wheats tabled by Zaharia for the nine year period 1900 to 1908 shows average values of +0.3653 for weight per unit volume, +0.4652 for protein content, and +0.5447 for quality index. The inter-annual correlations for rainfall are low, averaging only +0.1767 for May and +0.0869 for June. It is significant to note that, while these correlations represent interrelationships covering a range of nine crop years, the magnitudes of the correlations are not greatly affected by the period of separation of the two variables. With inter-annual coefficients of the magnitude of those determined herein, the prediction of future quality of wheat crops should be possible within a reasonable degree of accuracy. While this paper is based on Roumanian data, the primary consideration is that of the principle involved. There can be no reasonable doubt that similar results will be found for districts of other geographic areas. The magnitude of the correlation will depend upon the extent of differentiation of the districts in soil and climatic conditions.
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