Genetic Improvement in Winter Wheat Yields in the Great Plains of North America, 1959–2008

Data from USDA-coordinated winter wheat (Triticum aestivum L.) regional performance nurseries collected over the time period 1959 to 2008 were used to estimate genetic gain (loss) in grain yield, grain volume weight, days to heading, and plant height in winter wheats adapted to the Great Plains of North America. In both the Southern Regional (SRPN) and Northern Regional Performance Nurseries (NRPN), linear regression revealed signifi cant positive relationships between relative grain yields of advanced breeding lines and calendar year of the nursery trial. The estimated genetic gain in grain yield potential since 1959 was approximately 1.1% (of the control cultivar Kharkof) yr–1 for all entries in the SRPN, and 1.3% yr–1 if only the most productive entry was considered. For the NRPN, the estimates of genetic gain in grain yield were 0.79% yr–1 for all entries, and also 0.79% yr–1 for the most productive entry. Linear regressions of relative grain yields vs. year over the time period 1984 to 2008, however, showed no statistically signifi cant trend in the SRPN. For the same time period in the NRPN, a statistically signifi cant positive slope of 0.83 was observed, though the coeffi cient of determination (R2) was only 0.28. Relative grain yields of Great Plains hard winter wheats may have peaked in the early to mid1990s, and further improvement in the genetic potential for grain yield awaits some new technological or biological advance. R.A. Graybosch, USDA-ARS, 137 Keim Hall, East Campus, Univ. of Nebraska, Lincoln, NE 68583. C.J.Peterson, Dep. of Crop and Soil Science, 109 Crop Science Building, Oregon State Univ., Corvallis, OR 97331. Mention of fi rm names or trade products does not imply that they are endorsed or recommended by the USDA or the University of Nebraska over other fi rms or products not mentioned. Received 25 Nov. 2009. *Corresponding author ([email protected]). Abbreviations: NRPN, Northern Regional Performance Nurseries; SRPN, Southern Regional Performance Nurseries. Published in Crop Sci. 50:1882–1890 (2010). doi: 10.2135/cropsci2009.11.0685 Published online 23 July 2010. © Crop Science Society of America | 5585 Guilford 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.