A method of identifying a maize plant comprising at least 1 allelic variant associated with increased grain yield, said method comprising the following steps: i) obtaining plant material from a plant or a plant population to be tested and extracting DNA from said material; ii) analyzing the DNA sample obtained in step i) to determine the allelic variant present at at least 1 marker locus selected from the group consisting of M59/60-2, M77/78-2, M27/28-2, M47/48-2, M75/76-2, M65/66-2, M9/10-2, M69/70-1, M13/14-1, M73/74-1, M25/26-1, M35/36-1, M63/64-1, M41/42-1, M49/50-1, M61/62-1, M17/18-1, M51/52-1, M19/20-1, and M29/30-1, by a) identifying the at least one marker locus in a PCR reaction using a pair of PCR oligonucleotide primers consisting of a forward primer and a reverse primer, wherein the primers are SEQ ID NO: 59/60 for M59/60-2, SEQ ID NO:77/78 for M77/78-2, SEQ ID NO: 27/28 for M27/28-2, SEQ ID NO: 47/48 for M47/48-2, SEQ ID NO: 75/76 for M75/76-2, SEQ ID NO: 65/66 for M65/66-2, SEQ ID NO: 9/10 for M9/10-2, SEQ ID NO: 69/70 for M69/70-, SEQ ID NO: 13/14 for M13/14-1, SEQ ID NO: 73/74 for M73/74-1, SEQ ID NO: 25/26 for M25/26-1, SEQ ID NO: 35/36 for M35/36-1, SEQ ID NO: 63/64 for M63/64-1, SEQ ID NO: 35/36 for M35/36-1, SEQ ID NO: 41/42 for M41/42-1, SEQ ID NO: 49/50 for M49/50-1, SEQ ID NO: 61/62 for M61/62-1, SEQ ID NO: 17/18 for M17/18-1, SEQ ID NO: 51/52 for M51/52-1, SEQ ID NO: 19/20 for M19/20-1 and SEQ ID NO: 29/30 for M29/30-1, and wherein the allelic variant associated with increased grain yield at said at least one marker locus has a molecular weight of 120 bp for M59/60-2, 85 bp for M77/78-2, 350 bp for M27/28-2, 130 bp for M47/48-2, 170 bp for M75/76-2, 200 bp for M65/66-2, 70 bp for M9/10-2, 175 bp for M69/70-1, 350 bp for M13/14-1, 135 bp for M73/74-1, 125 bp for M25/26-1, 215 bp for M35/36-1, 160 bp for M63/64-1, 225 bp for M41/42-1, 120 bp for M49/50-1, 160 bp for M61/62-1, 100 bp for M17/18-1, 240 bp for M51/52-1, 100 bp for M19/20-1, and 225 bp for M29/30-1 respectively; iii) identifying and selecting a plant comprising at least 1 allelic variant associated with increased grain yield; wherein grain yield is measured in quintals per hectare. i) obtaining plant material from a plant or a plant population to be tested and extracting DNA from said material; ii) analyzing the DNA sample obtained in step i) to determine the allelic variant present at at least 1 marker locus selected from the group consisting of M59/60-2, M77/78-2, M27/28-2, M47/48-2, M75/76-2, M65/66-2, M9/10-2, M69/70-1, M13/14-1, M73/74-1, M25/26-1, M35/36-1, M63/64-1, M41/42-1, M49/50-1, M61/62-1, M17/18-1, M51/52-1, M19/20-1, and M29/30-1, by a) identifying the at least one marker locus in a PCR reaction using a pair of PCR oligonucleotide primers consisting of a forward primer and a reverse primer, wherein the primers are SEQ ID NO: 59/60 for M59/60-2, SEQ ID NO:77/78 for M77/78-2, SEQ ID NO: 27/28 for M27/28-2, SEQ ID NO: 47/48 for M47/48-2, SEQ ID NO: 75/76 for M75/76-2, SEQ ID NO: 65/66 for M65/66-2, SEQ ID NO: 9/10 for M9/10-2, SEQ ID NO: 69/70 for M69/70-, SEQ ID NO: 13/14 for M13/14-1, SEQ ID NO: 73/74 for M73/74-1, SEQ ID NO: 25/26 for M25/26-1, SEQ ID NO: 35/36 for M35/36-1, SEQ ID NO: 63/64 for M63/64-1, SEQ ID NO: 35/36 for M35/36-1, SEQ ID NO: 41/42 for M41/42-1, SEQ ID NO: 49/50 for M49/50-1, SEQ ID NO: 61/62 for M61/62-1, SEQ ID NO: 17/18 for M17/18-1, SEQ ID NO: 51/52 for M51/52-1, SEQ ID NO: 19/20 for M19/20-1 and SEQ ID NO: 29/30 for M29/30-1, and wherein the allelic variant associated with increased grain yield at said at least one marker locus has a molecular weight of 120 bp for M59/60-2, 85 bp for M77/78-2, 350 bp for M27/28-2, 130 bp for M47/48-2, 170 bp for M75/76-2, 200 bp for M65/66-2, 70 bp for M9/10-2, 175 bp for M69/70-1, 350 bp for M13/14-1, 135 bp for M73/74-1, 125 bp for M25/26-1, 215 bp for M35/36-1, 160 bp for M63/64-1, 225 bp for M41/42-1, 120 bp for M49/50-1, 160 bp for M61/62-1, 100 bp for M17/18-1, 240 bp for M51/52-1, 100 bp for M19/20-1, and 225 bp for M29/30-1 respectively; a) identifying the at least one marker locus in a PCR reaction using a pair of PCR oligonucleotide primers consisting of a forward primer and a reverse primer, wherein the primers are SEQ ID NO: 59/60 for M59/60-2, SEQ ID NO:77/78 for M77/78-2, SEQ ID NO: 27/28 for M27/28-2, SEQ ID NO: 47/48 for M47/48-2, SEQ ID NO: 75/76 for M75/76-2, SEQ ID NO: 65/66 for M65/66-2, SEQ ID NO: 9/10 for M9/10-2, SEQ ID NO: 69/70 for M69/70-, SEQ ID NO: 13/14 for M13/14-1, SEQ ID NO: 73/74 for M73/74-1, SEQ ID NO: 25/26 for M25/26-1, SEQ ID NO: 35/36 for M35/36-1, SEQ ID NO: 63/64 for M63/64-1, SEQ ID NO: 35/36 for M35/36-1, SEQ ID NO: 41/42 for M41/42-1, SEQ ID NO: 49/50 for M49/50-1, SEQ ID NO: 61/62 for M61/62-1, SEQ ID NO: 17/18 for M17/18-1, SEQ ID NO: 51/52 for M51/52-1, SEQ ID NO: 19/20 for M19/20-1 and SEQ ID NO: 29/30 for M29/30-1, and wherein the allelic variant associated with increased grain yield at said at least one marker locus has a molecular weight of 120 bp for M59/60-2, 85 bp for M77/78-2, 350 bp for M27/28-2, 130 bp for M47/48-2, 170 bp for M75/76-2, 200 bp for M65/66-2, 70 bp for M9/10-2, 175 bp for M69/70-1, 350 bp for M13/14-1, 135 bp for M73/74-1, 125 bp for M25/26-1, 215 bp for M35/36-1, 160 bp for M63/64-1, 225 bp for M41/42-1, 120 bp for M49/50-1, 160 bp for M61/62-1, 100 bp for M17/18-1, 240 bp for M51/52-1, 100 bp for M19/20-1, and 225 bp for M29/30-1 respectively; iii) identifying and selecting a plant comprising at least 1 allelic variant associated with increased grain yield;