Effect of temperature on soybean seed constituents: Oil, protein, moisture, fatty acids, amino acids and sugars

Soybean plants were grown at day/night temperatures of 24/19 C until the beginning of seed development, and then transferred to 5 different temperature regimes (18/13, 24/19, 27/22, 30/25 and 33/28 C) in the CSIRO phytotron. Mature seeds that developed under these conditions were analyzed for variances in composition. Fatty acid composition was strongly affected by temperature: linolenic and linoleic acids decreased markedly whereas oleic acid increased as the temperature increased; palmitic and stearic acids remained unchanged. Oil content was positively correlated with temperature, and protein content increased at the highest temperature. Of the sugars analyzed, sucrose concentration decreased by 56% with a 15 C increase in temperature, and stachyose showed a slight reduction; other sugars remained unchanged. Amino acid composition was generally stable; however, methionine increased with increased temperature during seed development. Moisture content was unaffected.