Stability of linolenic acid in seed oil of soybean accessions with elevated linolenic acid concentration

Increasing linolenic acid composition in soybean [Glycine max (L.) Merr.] seed oil is desirable to lower the ratio of linoleic to linolenic acid. Linolenic acid content that varies in soybean oil is affected by temperature of the growing environment during the reproductive growth stage. The objective of this study was to evaluate stability of linolenic acid composition among 18 plant introductions (Pls) with linolenic acid contents ranging from 85 to 155 g kg -1 and two checks in 10 environments. Linolenic acid concentration of the commercially grown normal and elevated linolenic acid varieties Taekwang and Daemang averaged 79 and 93 g kg -1 , respectively. Linolenic acid composition of each plant introduction and check varieties varied over environments and had a negative relationship with mean maximum temperature during the final 30 days of the reproductive stage. Four stability parameters range, coefficient of variation and two stability coefficients (b T and b E ) were used to measure the stability of linolenic acid. PI593997, PI153245 and PI587632B were relatively more stable across 10 environments. PI189950 (107 g kg -1 ) had the highest average linolenic acid composition and showed the lowest (4.8) linoleic to linolenic acid ratio. Thus, linolenic acid content of these elevated PIs and check varieties was too low over the 10 environments to consistently provide soybean oil with a linoleic to linolenic acid ratio of <4 to 1 desired in food or supplements for added health benefits.