Several yield-related traits selected during crop domestication and improvement 1 , 2 are associated with increases in meristem size 3 , which is controlled by CLE peptide signals in the CLAVATA–WUSCHEL pathway 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 . Here, we engineered quantitative variation for yield-related traits in maize by making weak promoter alleles of CLE genes, and a null allele of a newly identified partially redundant compensating CLE gene, using CRISPR–Cas9 genome editing. These strategies increased multiple maize grain-yield-related traits, supporting the enormous potential for genomic editing in crop enhancement.