Abstract <p>The studies aimed to develop a sunflower population homozygous for the dominant allele of the broomrape resistance gene of the G_RU race under conditions of open pollination. The efficiency of using DNA markers of the <i>HaOr7</i> gene for selecting resistant homozygous plants from a population of F₅ hybrids from crossing the resistance donor line RG with the recipient—the confectionery variety SPK plus—was studied. In December 2023, under protected ground conditions and artificial infection, an assessment of the resistance of 273 plants of the F₅ RG × SPK plus population and 16 plants of the control susceptible variety VNIIMK 8883 to broomrape race G_RU was carried out. Control-level damage (from 21 to 34 attached broomrape tubercles) was observed in 11 plants, it varied from five to 13 tubercles in 18 plants, and high resistance was observed in the remaining 244 plants: from zero to four tubercles. The alleles of the <i>HaOr7</i> gene were determined using multiplex PCR with markers for the presence or absence of dominant and recessive alleles: 151 plants were found to be homozygous for the dominant allele, 11 for the recessive allele, and 111 heterozygous. All 11 plants homozygous for the recessive allele were susceptible to broomrape with damage at the control level: 25.54 tubercles; homozygous for the dominant allele and heterozygotes showed resistance with an average number of tubercles of 0.32 and 1.80, respectively. The proportion of heterozygotes among 160 phenotypically resistant plants was 28.8%, which suggests further segregation in the population and a decrease in the efficiency of selection with each generation. A combination of phenotypic assessment with marker-assisted selection is recommended to increase the efficiency of breeding confectionery sunflower varieties resistant to broomrape. As a result of using two assessment methods, 66 completely resistant plants homozygous for the dominant allele were selected for further breeding based on economically valuable traits.</p>