T he phenotype of an individual plant may be determined not only by its genotype and the environment in which it develops but also by maternal eff ects. Maternal eff ects in plants occur when the maternal parent contributes to the phenotype of its off spring beyond the equal chromosomal contribution from each parent. Maternal eff ects can have a profound impact on selection, especially if the units of selection are seeds produced on a single plant. For instance, selection for altered seed composition in soybean [Glycine max (L.) Merr.] is sometimes based on the phenotype of a chip from a single seed or the phenotypes of bulked seeds from heterozygous plants in early generations of inbreeding (Wilcox and Cavins, 1985). Maternal plant infl uence on seed phenotype would likely aff ect selection decisions in such cases. Understanding how maternal eff ects infl uence this selection can lead to the development of more effi cient breeding strategies and result in an increase in genetic gain.Roach and Wulff (1987) described three types of maternal eff ects and classifi ed them as cytoplasmic genetic, endosperm nuclear, and maternal phenotypic. In the botanical context, cytoplasmic genetic maternal eff ects occur when the maternal parent passes genes located in the cytoplasm that aff ect a certain trait to her off spring. In self-pollinated species, these eff ects are heritable and are typically detected in each successive generation of inbreeding. If cytoplasmic nuclear genetic eff ects exist, the eff ects may dissipate or appear, depending on the interaction, for example, the cytoplasmic male-sterile-nuclear ABSTRACT The success of genetically altering the fatty acid composition of soybean (Glycine max (L.) Merr.) seed oil is determined by the rate of genetic gain through selection. Maternal effects can infl uence genetic gain. Objectives of this study were to investigate the presence and magnitude of maternal effects on fatty acid content of soybean oil. Maternal effects for unsaturated fatty acid content were evaluated over 2 yr using reciprocal F 1 soybean seed from crosses between the mid-oleic/low-linolenic line 'N98-4445A' and six cytoplasmically diverse cultivars. Maternal effects were signifi cant across genetically diverse materials and likely the result of the phenotype of the maternal plant. The magnitude of the maternal effect was typically less when N98-4445A was used as the maternal parent. These data suggest that selection based on the oil composition of single F 2 seeds might be ineffective but less so if the altered fatty acid parent is the maternal parent. Maternal effects on saturated fatty acid content were evaluated both in the fi eld and in vitro using reciprocal F 1 soybean seed from the cross between the high-palmitic line 'N02-4441' and 'Dare'. Maternal effects were signifi cant when grown in the fi eld. When reciprocal F 1 and parental 25 d old embryo seeds were grown in vitro, maternal effects between reciprocal crosses were not apparent, while signifi cant differences between the parents were...