Genotypic Adaptation of Rice to Lowland Hydrology in West Africa

Lowlands in West Africa are characterized by a diverse hydrology, wherein some areas are submerged in flood while other areas are permanently in non-flooded conditions. Thus, rice breeding programs must come up with genotypes that could thrive in either conditions or for a target population of environments. K. Saito of Africa Rice Center, Benin, and colleagues evaluated 14 rice genotypes in seven experiments for two years to investigate the effect of genotype and environment on grain yield, and to identify high-yielding genotypes and plant characteristics linked with high yield.

The studied Oryza sativa indica genotypes, including ‘aerobic rice genotypes' and interspecific genotypes, were developed from crossing O. sativa and O. glaberrima for upland (‘NERICA' genotypes) and lowland conditions (‘NERICA-L'). Higher grain yields were observed from flooded lowland conditions. Three environment groups were identified based on water availability: aerobic, hydromorphic (rainfed during growth, with drought spells during vegetative stage), and permanently flooded. An interspecific genotype (WAB1159-4-10-15-1-3) produced high yield in flooded and hydromorphic environments. Other interspecific genotypes (NERICA-L-6 and NERICA –L-54) exhibited high yields only in flooded environments. However, an aerobic rice genotype (B 6144F-MR-6-0-0) produced more yield than those three interspecific genotypes in aerobic conditions. In hydromorphic environments, grain yield was found to be correlated with growth duration.

The researchers concluded that interspecific breeding could be an efficient technique in enhancing lowland rice productivity, and also recommend a systematic effort to screen and identify rice genotypes that perform well across or within specific target population of environments in West Africa.

Read more about this study in the recent issue of Field Crops Research Journal at http://dx.doi.org/10.1016/j.fcr.2010.07.020.