Detection of Epistatic, Additive, and Dominance Variation in Winter Wheat (<i>Triticum aestivum</i> L. em Thell.)¹

<jats:p>The objectives of this study were to determine whether epistasis plays a significant role in the genetic systems for selected traits among several winter wheat (<jats:italic>Triticum aestivum</jats:italic> L. em Thell.) cultivars and to evaluate the importance of additive vs. dominance gene action for traits not influenced by epistasis. In each of two replicated experiments, two cultivars (referred to as testers L<jats:sub>1</jats:sub> and L<jats:sub>2</jats:sub>) and their F<jats:sub>1</jats:sub> (L<jats:sub>3</jats:sub>) were crossed to each of 10 other cultivars and evaluated in a single field experiment. The deviations (cultivar ✕ L<jats:sub>1</jats:sub> + cultivar ✕ L<jats:sub>2</jats:sub> — 2 cultivar ✕ L<jats:sub>3</jats:sub>) were analyzed to provide a test for epistasis. An additive‐lominance model was fitted to the data for those characters not affected by gene interactions.</jats:p><jats:p>Results of the two experiments were generally consistent with respect to the detection of epistasis. Epistasis affected the expression of heading date, kernels/spikelet, and grain yield, but not of plant height, protein content, tiller number, spikelets/spike, and kernels/spike in both experiments. Epistasis was indicated for kernel weight in one experiment but not the other. Expression of epistasis was influenced by particular cultivars, indicating that a limited number of cultivars may not be sufficient to detect nonallelic interactions for a character within this species.</jats:p><jats:p>Additive gene action was predominant in both experiments for protein content, spikelets/spike, and kernels/spike, suggesting that improvement of those characters can be achieved through standard selection procedures. Evidence for dominance gene action was obtained for plant height and kernels/spike in one experiment.</jats:p><jats:p>The results of this study indicated that epistasis may be a nontrivial factor in the inheritance of agronomic traits. Genetic models neglecting epistasis may result in biased information.</jats:p>