Postembryonic primary root growth relies on meristems that harbour multipotent stem cells that produce new cells that will duplicate and provide all the different root cell types. Arabidopsis thaliana primary root growth has become a model for evo-devo studies due to its simplicity and facility to record cell proliferation and differentiation. To identify new genetic components relevant to primary root growth, we used a Genome-Wide Association Studies (GWAS) meta-analysis approach using data published in the last decade. In this work, we performed intra and inter-studies analyses to discover new genetic components that could participate in primary root growth. We used 639 accessions from nine different studies and performed different GWAS tests ranging from single studies and pairwise analysis with high correlation associations, analyzing the same number of accessions in different studies to using the daily data of the root growth kinetic of the same research. We found that primary root growth changes were associated with 41 genomic loci, of which six (14.6%) have been previously described as inhibitors or promoters of primary root growth. The knockdown of genes associated with two of these loci: a gene that participates in Trans-acting siRNAs (tasiRNAs) processing Suppressor of Gene Silencing (SGS3) and a gene with a Sterile Alpha Motif (SAM) confirmed their participation as repressors of primary root growth. As none has been shown to participate in this developmental process before, our GWAS analysis identified new genes that participate in primary root growth. Overall, our findings provide novel insights into the genomic basis of root development and further demonstrate the usefulness of GWAS meta-analyses in non-human species.