Changes in agronomic and seed characteristics with selection for reduced palmitic acid content in soybean

Development of soybean [Glycine mar (L.) Merr.] cultivars,vith reduced saturated fatty acid content is an important goal of soybean breeders. The objective of this study was to determine if genes for reduced palmitic acid content in the fatty acid germplasm N87-2122-4 were associated with changes in agronomic and seed quality characteristics. Approximately 22 reduced (54-72 g kg(-1)) and 22 normal (90-119 g kg(-1)) palmitic acid F-5:7 lines were sampled from each of two crosses N87-2122-4 x 'Kenwood' and N87-2122-4 x 'P9273' and grown in replicated tests at four North Carolina locations. Lines homozygous for the major reduced palmitic acid gene produced significantly (P < 0.01) less (approximate to 10%) seed yield than lines homozygous for the normal gene. Furthermore, selection differentials for the normal palmitic acid populations were significantly (P < 0.01) larger than for the reduced palmitic acid population. Oleic and linolenic acid contents were significantly (P < 0.01) greater for reduced palmitic acid lines, while the major reduced palmitic acid gene had no significant (P > 0.05) effect on linoleic and seed protein contents. Seed oil content was significantly (P < 0.05) greater among reduced palmitic acid Lines in the N87-2122-4 x Kenwood cross only. Genetic correlations were estimated among lines to examine the influence of selection for palmitic acid genetic modifiers on agronomic traits. Palmitic acid content was significantly (P < 0.05) and negatively correlated with changes in oleic acid, and significantly (P < 0.05) and positively correlated with changes in linolenic add contents. Genetic modifiers conditioning palmitic acid content seemed independent of genes controlling seed yield, suggesting that selection for reduced palmitic acid content among Lines homozygous for the reduced palmitic acid gene may be achieved without a reduction in seed yield. Efforts to further reduce palmitic acid content in populations fixed for the major palmitic acid gene should improve the quality of soybean oils produced for food processing markets.