Heterosis, gene redundancy, and self-fertilization are three advantages of a plant becoming polyploid. Polyploid plants show greater long-term adaptability to evolution than their corresponding diploids and are shielded from the harmful effects of mutations.
Heterosis is defined as a crossbred plant species having superior qualities than those of either of its parents. Polyploid plants take advantage of this in several ways. For example, allopolyploids, which are polyploids with chromosomes derived from different species, prevent intergenomic recombination, which allows subsequent generations to have the same amount of varied sets of chromosomes or different alleles corresponding to the same position on chromosomes. Essentially that means greater genetic variety.
Gene redundancy is when several genes of a plant species perform the same function, so if one gene mutates in a way that is not beneficial to the plant, there are others to take over the necessary functions the organism needs to survive. One way polyploid plants take advantage of gene redundancy is by masking recessive genes. An example of a recessive gene in humans is red hair. A person with red hair must have two red hair genes. Any other hair color gene is dominant over red and masks its expression. In plants, recessive traits tend to be damaging, so expressing dominant genes is advantageous to its survival. Gene redundancy also allows plants to diversify gene function.