Food security is affected by several factors,one of the most important of which is the in the quantitative  and qualitative  increase of agricultural products. For the reason the role of rice in the daily nutrition of Iranians and the need to increase the efficiency of limited territorial resources, we are forced to increase the yield per unit area. Identifying genotypes that contain alleles of genes related to yield improvement is one of the methods of rice plant breeding so that these genotypes, so that these genotypes can be used in breeding programs, to produce high-yield varieties, in plant breeding programs to produce high-yielding cultivars. Considering the importance of the number of seeds in the panicle and its effect in increasing the yield per unit area, in this research, among several genes related to yield, the screening of rice genotypes was investigated using  on the functional marker related to the Gn1a gene. In this research, 52 local and improved genotypes of rice were prepared from the collection of the Rice Research Institute of Iran and the grain number trait was investigated based on phenotypic and molecular evaluations in the field related to the band pattern created by a specific primer pair Grain number 1a gene (Gn1a) contiguous with the gene location controlling the grain number trait. The result of the genetic evaluation led to the identification of 15 cultivars with the allele of the large number of seeds gene and 37 cultivars without the allele of this gene, which, according to the phenotypic evaluation that confirmed it, shows the reliability and accuracy of the marker used to predict and differentiate cultivars for the program breedings are forthcoming. The logistic regression results also confirmed this result. However, a number of other examined samples also had a high number of seeds, which indicates the existence of other genes affecting the number of seeds per panicle in those lines.