The relation between yield and protein in cereal grain

Abstract An analysis of published data on genetic relations between dry grain yields (y, t ha −1 ) and protein content p , protein as a fraction (g g −1 ) of dry grain of cereals is presented. In all, 106 usable regressions of y on p across geneotypes were assembled. The long‐recognised negative relation between yield and protein concentration was fully substantiated. There is a strong positive relation between grain yield and protein yield. The linear regression coefficient of yield on protein concentration is related to yield, with slope about −15. This relation holds approximately over all cereals. The data can be used to estimate a characteristic parameter described by C = dy/d( yp ) = ∼ 15–25 at the mean of each experiment. The relationship is surprisingly consistent but no simple physiological interpretation is available. In discussion, the high C , the impact of strong negative regressions of y on p for breeding strategies, the fact that protein yield increases with gross grain yield but at falling p and certain socio‐economic consequences are emphasized. An acute need for orderly reporting of experimental data is also emphasised; the existing literature is chaotic as to units, moisture contents and conversion factors.