Yields of cereal grain and protein

Earlier work has shown that, in cereals in general, grain yield (Y) and protein content (P) are strongly negatively related. It is shown here that the expected positive expected relationship between grain yield and protein yield also holds, with (YP) given approximately by YP = 0.141 + 0.0969 Y. All cereal breeding in which high protein content is desired therefore faces a compromise with grain yield.