Choose the incorrect statement.

Many of the extrinsic factors such as temperature and light, control plant growth and development via PGR.

Seed coat barrier in some seeds can be broken by mechanical abrasions using knives, sandpaper, etc. or vigorous shaking.

Roles of PGRs could be complimentary or antagonistic as well as could be individualistic or synergistic. 

Biennials are bicarpic plants that normally flower and die in the second season.