Indirect selection for grain protein and grain yield in winter wheat

Summary

Increasing grain protein content is an important wheat breeding goal. Noaman & Taylor (1988b) showed the combination of protein content in the head, peduncle, and flag leaf of winter wheat at heading provided a good estimate for grain protein. The objectives of this research were to apply these results in indirect selection scheme for grain protein improvement and to study the heritability of protein content in these plant parts. Two random winter wheat populations from four parents in double crosses were used in this study. Sixty randon F2-derived F5 and F6 lines were grown in randomized complete block design with 3 replicates in two years. Significant differences for grain yield, grain protein, and vegetative protein content were detected among F5 and F6 lines in both populations. Genotypic and phenotypic correlations between grain protein and vegetative protein were significant and in agreement. Estimates of narrow sense heritability of protein content using variance components method ranged from 0.46 to 0.94 for leaf 2 and head in population 1, and from 0.63 to 0.89 for peduncle and head in population 2. Correlation coefficients (r) between predicted and observed grain protein ranged from 0.50 to 0.88 and from 0.37 to 0.84 in populations 1 and 2, respectively. The highest r was obtained from the combination of head, peduncle, and flag leaf protein at heading. Correlation between protein in plant parts and grain yield was small and not significant. The high heritability of vegetative protein at heading allows the identification of genotypes before pollination which are likely to produce high grain protein. Indirect selection for head, peduncle, and flag leaf protein should result in increased grain protein without yield reduction noted in other breeding schemes.