The use of grain protein deviation for identifying wheat cultivars with high grain protein concentration and yield

The relationship between grain protein concentration and grain yield in dif ferent cultivars of winter wheat was examined in a series of field experime nts carried out over three years, in which 13, 12 and 8 cultivars were stud ied in each year, respectively. The plants were grown at sites located in S hropshire, west-central England, in years 1 and 2, and at three other locat ions in eastern England in year 3. Above ground plant samples were collecte d at anthesis and again at maturity, when they were separated into grain an d straw, and analysed for dry matter and N content. Analysis of residuals f rom regression of grain protein concentration on grain yield (grain protein deviation, GPD) showed that some cultivars had a higher grain protein conc entration than was predicted from grain yield alone. It was deduced that th e capacity to accumulate a higher grain protein concentration than predicte d from grain yield is under genetic control and thus may be improved throug h breeding. Other factors (weight of N accumulated in the biomass at anthes is, weight of N accumulated in the biomass between anthesis and maturity an d the concentration of N remaining in the straw at maturity) were added ste p-wise into the regression to enable statistical analysis of their relative contributions to grain protein. High GPD may be achieved through increased N accumulation after anthesis, combined with efficient re-translocation of vegetative N reserves. The use of GPD provides a selection criteria in whe at breeding programs to screen for increased grain protein concentration wi thout a concurrent grain yield reduction.