Botany - Plant Growth and Development Question with Solution | TestHub

Flowering is a phytochrome regulated process. Phytotchrome is a blue protein pigment with a molecular mass of about $125\mathrm{k}\mathrm{Da}$ (kilodaltons). Phytochrome occurs in two interconvertible form $P_R$ (which absorbs red light) and ${\mathrm{P}}_{\mathrm{fr}}$ (which absorbs far red light). The studies with mutants of Arabidopsis support and prove that the ${\mathrm{P}}_{\mathrm{fr}}$ is the active form of phytochrome. When ${\mathrm{P}}_{\mathrm{R}}$ molecules are exposed to red light, most of them absorb it and converted to ${\mathrm{P}}_{\mathrm{fr}}$. This causes floral induction in the shoot.