Solution:

Total number of plants obtained in F2 generation of dihybrid cross = 1200

To find out the plants with new phenotypic combination, we need to calculate the number of plants with the expected phenotypic ratio.

Expected phenotypic ratio in dihybrid cross = 9:3:3:1

Where 9 plants show dominant phenotype for both traits, 3 plants show dominant phenotype for one trait and recessive for the other trait, 3 plants show recessive phenotype for one trait and dominant for the other trait, and 1 plant shows recessive phenotype for both traits.

Let's calculate the expected number of plants for each phenotype:

- Dominant phenotype for both traits = 9/16 x 1200 = 675
- Dominant phenotype for one trait and recessive for the other trait = 3/16 x 1200 = 225
- Recessive phenotype for one trait and dominant for the other trait = 3/16 x 1200 = 225
- Recessive phenotype for both traits = 1/16 x 1200 = 75

Therefore, out of 1200 plants obtained in F2 generation, 300 plants (225 + 75) have new phenotypic combination, i.e. they show a combination of traits that was not present in the parental generation.

Conclusion:

In dihybrid cross, 1200 plants obtained in F2 generation, out of which 300 plants have new phenotypic combination. The expected phenotypic ratio can be used to calculate the number of plants with each phenotype.