Agronomic Management System and Precipitation Eff ects on Soybean Oil and Fatty Acid Profi les

This study investigated long-term agronomic management systems and precipitation level effects on soybean [Glycine max (L.) Merr.] total oil content and fatty acid composition. Management systems evaluated included conventional (CT), no-till (NT), low chemical input (LI), and zero chemical input (ORG). Total oil content and major fatty acids profi les were analyzed by accelerated solvent extractor (ASE 200) and gas chromatography with fl ame ionization detector (FID). The results showed these four management systems have limited infl uence on soybean grain total oil content and oleic acid (O) and linoleic acid (L) compositions. The NT management system signifi cantly improved soybean oil yield on a land-area basis as a result of higher annual grain yields. Soybeans grown under the NT management system had as high or higher palmitic acid (P) composition than the other three management systems; similarly, the CT treatments had as low or lower linolenic acid (LN) composition in soybean when compared with the other three management systems. The levels of stearic acid (S), O, L, and LN had a signifi cant quadratic relationship (R2 = 0.64–0.75) with total (July–September) precipitation. The oil quality ratio of O/(L + LN) had a quadratic relation with precipitation. Juan Gao, Xinmei Hao, Kurt D. Thelen, Dep. of Crop and Soil Science, Michigan State Univ., East Lansing, MI, 48824; G. Phillip Robertson, Dep. of Crop and Soil Science, Kellogg Biological Station, Michigan State Univ., East Lansing, MI, 48824. Received 22 Aug. 2008. *Corresponding author ( [email protected]). Abbreviations: CT, tilled conventional chemical-input system; den df, denominator degree of freedom; FAME, fatty acid methyl ester; FID, fl ame ionization detector; KBS, Kellogg Biological Station; L, linoleic acid; LI, tilled low chemical-input system; LN, linolenic acid; LTER, long-term ecological research site; NT, nontilled conventional chemicalinput system; num df, numerator degree of freedom; O, oleic acid; ORG, tilled no-chemical-input system; P, palmitic acid; S, stearic acid. Published in Crop Sci. 49:1049–1057 (2009). doi: 10.2135/cropsci2008.08.0497 © Crop Science Society of America 677 S. Segoe Rd., Madison, WI 53711 USA All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Permission for printing and for reprinting the material contained herein has been obtained by the publisher.