Phytosanitary Evaluation of 54 Rice Accessions Under Iron Toxicity in Burkina Faso

Abstract

The Kou Valley in Burkina Faso experiences abiotic and biotic stresses, including iron toxicity and prevalent rice diseases, which restrict the productivity of local varieties. This study evaluated the tolerance of 54 rice accessions to iron toxicity and major diseases to identify sources of resistance and tolerance. Physicochemical soil analyses were performed at depths of 0-20 cm and 20-40 cm. The incidence and severity of iron toxicity, as well as of rice blast, helminthosporiosis, bacterial leaf blight, bacterial leaf streak and Rice yellow mottle virus were evaluated according to the IRRI scale. Results showed slightly acidic soil with a silt-loam texture at the surface and a silt-clay-loam texture at depth, and significantly higher free iron content in the 0-20 cm layer. Iron toxicity became widespread across all accessions 60 days after transplanting, with varying levels of severity. Some accessions and controls, such as G49 and G42, exhibited low severity, whereas other accessions, notably G17 and G28, exhibited high severity. Highly significant differences were observed between accessions for all evaluated diseases. Hierarchical classification identified four distinct groups, including one with low severity for all diseases, which is of interest for varietal selection. These results highlight significant genetic variability with regard to iron toxicity and the main rice diseases, offering promising prospects for varietal improvement and integrated stress management in irrigated environments in Burkina Faso.