Temperature and Oleic Acid Seed Content: Correlation in Soybean Populations with Different Maturity Profiles.

Temperature effects are primarily responsible for the environmentally induced variation of the unsaturated fatty acid composition in soybean seed. Temperature increase during the seed-filling stage, which coincides with the period of oil deposition, typically leads to the elevation of oleate content in soybean oilseeds. In this study, three soybean populations consisting of 721 F5-derived lines (N98-4445A x ‘Satelite’), 118 F5-derived lines (N97-3363-3 x PI423893) and 231 F3-derived lines (N98-4445A x PI423893), which segregated for oleate content and maturity, and differed in maturity profiles, were grown in replicated, multi-environment trials in North Carolina. Correlations between the average daily temperature, during the period of oil deposition, and oleate content were estimated for both the overall experimental lines of each population and for lines grouped according to maturity. In the soybean populations of earlier maturity, oleate content was negatively correlated with temperature averaged over the seed-filling stage. It was shown that experimental lines classified in the early maturity groups led to the negative correlation between temperature and oleate content in the early-maturing populations; while, lines of middle or late maturity led to positive correlations in the late-maturing population. Temperature during seed-filling was positively correlated with oil content for all three populations, regardless of their maturity profile. The strong positive correlations between temperature and photoperiod during seed-filling suggested that further investigation is necessary to determine which of the two is responsible for the changes in the unsaturated fatty acid composition.