Additional file 2: Fig. S1. Representative plants used for RNA-seq. Fig. S2. Analysis of differentially expressed genes (DEGs) under various light conditions. Fig. S3. GO enrichment categories of F1-MPV DEGs under various light conditions. Fig. S4. Patterns of light and genotypic effects on maize metabolomes. Fig. S5. Analysis of differentially accumulated metabolites in hybrids under various light conditions. Fig. S6. qRT-PCR confirmation of specific DEGs under various light conditions. Fig. S7. WGCNA analysis of F1-MPV differentially accumulated metabolites (DAMs). Fig. S8. Phenylpropanoid biosynthesis pathway under various light conditions. Fig. S9. MPH validation of 45 selected genes. Fig. S10. Biomass heterosis at the seedling stage under various light conditions.