Evaluation of Rice yellow mottle virus Resistance and its Impact on Agronomic Performance in Aromatic Rice Lines
Rice yellow mottle virus (RYMV) is one of the most destructive viral diseases limiting rice production in Africa. Identifying genotypes that combine resistance with superior agronomic performance is essential for developing improved cultivars. This study evaluated 61 aromatic rice lines and three reference genotypes differing in RYMV resistance under greenhouse conditions using healthy and mechanically inoculated plants. Agronomic and disease-related traits were analysed by two-way analysis of variance (ANOVA), principal component analysis (PCA), hierarchical clustering on principal components (HCPC), and the Multi-trait Genotype–Ideotype Distance Index (MGIDI). RYMV infection significantly affected all measured traits (P < 0.001), reducing grain yield (65.3%), above-ground biomass (23.6%), plant height (13.6%), panicle length (11.2%), panicle number (13.3%), and thousand-grain weight (16.2%), while increasing spikelet sterility by 208.0%. Significant genotype × health interactions revealed contrasting responses among genotypes. PCA explained 59.0% of the total phenotypic variation and showed that yield-related traits were negatively associated with spikelet sterility and disease severity. HCPC grouped the genotypes into four distinct clusters according to their agronomic performance and disease response. MGIDI identified ten superior genotypes (Remar2, Remar4, Remar11, Remar13, Remar28, RemarGT, K20-26, K20-Germ13, Basmati370, and the highly resistant control TOG5681) that combined high yield potential with reduced disease impact. These genotypes constitute valuable genetic resources for breeding high-yielding, RYMV-resistant aromatic rice cultivars.