CROP SCIENCE, VOL. 50, JANUARY– FEBRUARY 2010 281 RESEARCH I n West Africa, rice ( Oryza spp.) is developing as a major staple food crop. While rice production has increased by around 170% from the 1970s to early 2000s, it has never caught up with con- sumer demand (Africa Rice Center, 2007) so that only around 40% of current rice consumption is satisfed by domestic produc- tion. Despite the traditional predominance of upland rice (cur- rently 40% of the rice-planted area), the rising demand for rice production is more likely to be satisfed in the lowlands where there is substantial potential for expansion and currently a large gap between yield potential and farm yields (Windmeijer and Andriesse, 1993; Becker and Johnson, 1999; Becker et al., 2003). Becker et al. (2003) reported that average lowland rice yields in diferent ecological zones in West Africa ranged from 3.4 to 5.1 Mg ha –1 and the yield gaps ranged from 3.3 to 5.9 Mg ha –1 . Low soil-nutrient availability and poor water management were the major factors causing the large yield gaps in this region (Wopereis et al., 1999; Becker and Johnson, 2001; Balasubramanian et al., 2007). Since the cost of fertilizer is increasing and resource-poor farmers in the fragile environments cannot aford to buy fertilizer, identifcation or development of rice genotypes that are adapted to nonfertilized conditions and have high responsiveness to nutrient inputs would be an attractive and cost-efective approach (Ladha Grain Yield Performance of Selected Lowland NERICA and Modern Asian Rice Genotypes in West Africa K. Saito,* K. Azoma, and M. Sié ABSTRACT Six lowland experiments were conducted over three years in southern Benin to assess yield differences in 28 rice (Oryza spp.) genotypes grown under nonfertilized and fertilized condi- tions. These included the interspecific hybrids, the lowland New Rice for Africa (NERICA) geno- types developed from crossing O. sativa and O. glaberrima. Fertilizer rates were 70–86N: 30–37P 2 O 5 : 30–37K 2 O kg ha –1 . Fertilizer appli- cation increased average grain yield across all genotypes and experiments by 39% (154 g m –2 increase). Considerable genotypic differences existed in grain yields under both nonfertilized and fertilized conditions, and in yield response to fertilizer application. Two lowland NERICA genotypes (‘NERICA-L-6’ and ‘-54’) outyielded ‘IR 72’ and ‘WITA4’ (standard checks) across nonfertilized and fertilized conditions in four experiments with favorable water availability in wet seasons (651 vs. 575 g m –2 ). The high grain yields resulted from large spikelet number m –2 and biomass accumulation. In contrast, three indica genotypes from Asia (‘B 6144F-MR-6-0- 0’, ‘IR 70181-32-PMI-1-1-5-1’, and ‘PSBRc 80’) outperformed the checks in two experiments, one straddling wet and dry seasons and the other with no standing water during most of the usual wet rice-growing season. These results indicate that while specific adaptations are likely to provide significant yield advantage in particular environments, interspecific breeding still offers an effective approach to improving lowland rice productivity. K. Saito, K. Azoma, and M. Sié; Africa Rice Center (WARDA), 01 BP 2031, Cotonou, Benin. The Ministry of Foreign Afairs of Japan provided the fnancial support for this research. Received 6 May 2009. *Corresponding author (k.saito@cgiar.org). Abbreviations: DAS, d after sowing; E, environment; EG, envi- ronment group; F, fertilizer, G, genotype; GG, genotype grouping; NERICA, New Rice for Africa; SOC, soil organic carbon content. Published in Crop Sci. 50:281–291 (2010). doi: 10.2135/cropsci2009.05.0245 © 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 January, 2010