Association of elevated palmitate with agronomic and seed traits of soybean
Conventional soybean [Glycine max (L.) Merr.] cultivars have approximately 11% palmitate in the seed oil. Increasing palmitate content may be beneficial for producing plastic fats at room temperature without the need for hydrogenation. Trans-fatty acids are produced from hydrogenation, which may be harmful to human health. The objective of the study was to compare soybean lines with 26%-palmitate content and lines with 40%-palmitate content for agronomic and seed traits. Three backcross populations were formed for this study. In each population, 27BC1F[Subscript 2:4] lines with 26%-palmitate and 27 lines with 40%-palmitate were tested at three locations in Iowa during 2000. The mean seed yield and content of oil in the 40%-palmitate lines were significantly less than that of the 26%-palmitate lines. None of the 40%-palmitate lines had a yield equal to any of the 26%-palmitate lines from the same population, and only one population had 40%-palmitate lines equal to 26%-palmitate lines for oil content. Protein content was significantly higher for the 40%-palmitate lines than the 26%-paimitate lines. The increase in protein did not compensate for the decrease in oil: therefore, the value of a metric ton of 40%-palmitate soybean was less than that of the 26%-palmitate type at current commodity prices for protein meal and oil. The 40%-palmitate lines had significantly lower mean plant population, lodging score, plant height, seed weight, oleate content, linoleate content, and stearate content than the 26%-palmitate lines in the three populations. Linolenate was significantly greater in the 40%-palmitate than the 26%-palmitate lines. The increase in palmitate content had adverse effects on agronomic and seed traits of soybean. Although there may be benefits of soybean oil with 40%-palmitate content, the negative associations with important agronomic and seed traits will make it difficult to develop cultivars that will be competitive with the conventional soybean.