Final answer:
The genotype ratio in the F2 generation when crossing plants with genotypes RR and rr will be 100% Rr.
Step-by-step explanation:
When crossing two plants with genotypes RR and rr, the genotype ratio in the next generation, F2 generation, will be 100% Rr. This is because when the dominant allele R and the recessive allele r are crossed, the resulting plants will have one copy of each allele. Therefore, all offspring will have the heterozygous genotype Rr.