PROTEIN AND GRAIN YIELD INHERITANCE IN FOUR POPULATIONS OF HARD RED WINTER WHEAT (TRITICUM AESTIVUM L.)

Grain-yield and grain-protein inheritance was investigated in crosses of six hard red winter wheat cultivars. Parents for these crosses consisted of four high-protein cultivars--Lancota Selection, Century II, 77Y10442, and 77Y10456; and two moderately low-protein cultivars--Newton and Bennett. Early-generation testing was carried out on the crosses of Newton/Lancota Selection and Lancota Selection/Century II. F(,1), F(,2), and backcrosses of these two crosses and their parents were planted in two separate field experiments. Early generations of the crosses of Bennett/77Y10442 and Lancota Selection/77Y10456 were evaluated in a similar fashion by Chaudhry (1982). Advanced generations (F(,3), F(,4), and F(,5)) of all four crosses also were evaluated in this study. Frequencies for grain-protein content, grain yield, number of grains per plant, 100-grain weight, number of spikes per plant, and number of grains per spike had normal distribution curves, suggesting quantitative inheritance for these traits. Heritability estimates for grain-protein content and grain yield, determined by the components of variance in the early generations and parent-offspring regressions in the advanced generations, were low and inconsistent in different generations. Heritability estimates were generally lower for grain yield than for grain-protein content. Both yield and protein expressions were under strong environmental influence. The mode of gene action varied in different crosses. Additive and additive x additive gene effects were significant in protein expression of Newton/Lancota Selection (low x high) crosses and additive gene effects had a major role in the protein expression of Lancota Selection/Century II (high x high) crosses. The modes of gene action and inconsistency in the heritability estimates suggest that several major and minor genes may be involved in protein expression in the crosses studied. Grain-protein content was negatively associated with grain yield but in varying magnitudes in different generations. The correlation coefficient for the highest negative association was -0.56 and the lowest was nearly zero. The major components of grain yield were number of grains per plant and number of spikes per plant