c06-08-0546(1) Prasad.indd

Selection criteria that can facilitate grain yield improvement would be considered important plant breeding tools. We assessed the value of spectral refl ectance indices (SRI) as indirect selection tools for grain yield improvement in winter wheat (Triticum aestivum L.). The objectives of this study were to estimate genetic correlation between SRI and grain yield, heritability, response to selection, correlated response of grain yield, and relative selection effi ciency of SRI for grain yield improvement. Three fi eld experiments consisting of 25 winter wheat cultivars and 2 sets of 25 recombinant inbred lines were conducted in the Oklahoma State University Agronomy Farm for 2 yr. Eight SRI were calculated at three growth stages (booting, heading, and grain-fi lling). The water-based indices (water index and normalized water indices) showed moderate to high heritability and higher genetic correlations with grain yield compared to the commonly used vegetation-based indices (normalized difference vegetation index and simple ratio). The water-based indices also showed higher correlated response than direct response for grain yield. Up to 83% of the top 25% highest-yielding genotypes were selected by the two newly developed water-based indices (normalized water index 3 [NWI-3] and normalized water index 4 [NWI-4]). These results suggest the strong genetic basis of NWI-3 and NWI-4 as potential selection tools for winter wheat grain yield improvement under Great Plains conditions. B. Prasad, B.F. Carver, W.R. Raun, and A.R. Klatt, Dep. of Plant and Soil Sciences, 368 Ag Hall, Oklahoma State Univ., Stillwater, OK 74078, USA; M.L. Stone, Dep. of Biosystems and Agricultural Engineering, Oklahoma State Univ., Stillwater, OK 74078, USA; M.A. Babar, Dep. of Agronomy, Kansas State Univ., Manhattan, KS 66506, USA. This research was partially funded by Oklahoma Agricultural Experiment Station, Oklahoma Wheat Commission, and Oklahoma Wheat Research Foundation. Received 28 Aug. 2006. *Corresponding author ([email protected]). Abbreviations: GNDVI, green normalized diff erence vegetation index; NWI, normalized water indices; NWI-1, normalized water index 1; NWI-2, normalized water index 2; NWI-3, normalized water index 3; NWI-4, normalized water index 4; RNDVI, red normalized diff erence vegetation index; SR, simple ratio; SRI, spectral refl ectance indices; WI, water index. Published in Crop Sci. 47:1416–1425 (2007). doi: 10.2135/cropsci2006.08.0546 © 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. Published online July 30, 2007