Essential Mineral Composition of Rice (Oryza Sativa L.) and Lettuce (Lactuca Sativa L.) Grown in the Lowlands of the City of Daloa, Côte d'IVOIRE

Micronutrient deficiency remains widespread in West Africa, where plant foods supply most mineral intake, yet the mineral value of rice and lettuce grown together in the urban lowlands of Daloa is poorly documented. This study aimed to determine the essential mineral contents of both crops, identify factors structuring their variability using multivariate statistics, and estimate their contribution to recommended daily intakes. Thirty stations in ten lowlands of Daloa were sampled from January 2024 to January 2025. Plant material was oven-dried, ground and dry-ashed at 600 °C, and Ca, Mg, Fe, Zn, Se and Mn were determined by flame atomic absorption spectrometry. Data were analysed with R for descriptive statistics, correlation analysis, Principal Component Analysis and Hierarchical Ascending Classification. Mineral contents varied widely, with Ca as the most abundant element (mean 887.72 mg/kg) and coefficients of variation ranging from 50.84% for Mg to 269.74% for Fe. Ca and Mg were strongly correlated (r=0.798), Fe, Zn and Se formed a second correlated group, and Mn behaved independently. The first two principal components explained 73.5% of total variance and separated stations into three groups reflecting a gradient of mineral richness, including a rice-specific group with very high Mn linked to waterlogging. Lettuce was richer than rice in Ca, Fe and Zn on dry-weight basis, but on fresh-weight basis only lettuce iron covered 39.3% of RDI per 100 g. Mineral contents are governed mainly by growing site rather than crop type, indicating that improving mineral quality requires better management of soil and water conditions.