Selection for High and Low Grain Protein in Six Winter Wheat Crosses1

Abstract

There has been a tendency for the more recent higher yielding cultivars of hard red winter wheat (Triticum aestivum L. em. Thell.) to have lower grain protein content. As a result of this, plant breeders are striving to maintain or increase grain protein levels. Six winter wheat populations involving three high‐protein (HP) and one “normal”‐protein (NP) genotypes were studied to determine the effectiveness of early generation selection for higher grain protein. The HP parents used were ‘Atlas 66’, ‘Flex’, and ‘Danne/Nap Hal’. The NP parent was KS73114. Three HP ✕ HP and three HP ✕ NP crosses were studied. Random spikes from the six F2 populations were grown as F3 head rows. Each cross was divided into four equal sized grids to reduce environmental bias on selection and 25 rows were selected from each grid to obtain 100 rows per cross. Each row was selected on the basis of acceptable agronomic characteristics and harvested. Percent grain protein was then determined by the Kjeldahl procedure. The five highest protein and five lowest protein lines per grid were then identified for a total of 20 high‐protein and 20 low‐protein lines per cross. The high‐low selections were grown as F4's in replicated tests at Stillwater, OK in 1979–1980. All crosses differed significantly for grain protein percentage between high‐protein and low‐protein selection groups, with differences ranging from 0.5 to 1.0% protein. No significant differences for grain yield between high‐protein and low‐protein groups were observed for three crosses. In two other crosses the low‐protein groups were significantly higher yielding than the high‐protein groups while the reverse was found in the remaining cross. Realized heritability estimates for grain protein ranged from 0.39 to 0.61. Phenotypic correlation coefficients of grain protein and grain yield were negative for all crosses and statistically significant, ranging from −0.32 to −0.60. The use of grids in this study resulted in an average 9.2% increase in efficiency of selection for grain protein.