(b) (i) Write any four points regarding Physiological effects of cytokinins.
(ii) Define Vernalisation.
(iii)
In the above representation, what does `P_(r)` and `P_("fr")`stand for ?

Explanation

(b) (i) Physiological effects of cytokinins :
1. Cytokinin promotes cell division in the presence of auxin (IAA)
2. Cytokinin can break the dormancy of certain light-sensitive seeds like tobacco and induces seed germination
3. Cytokinin promotes the growth of lateral bud in the presence of apical bud
4. Cytokinin (i) increases rate of protein synthesis (ii) induces the formation of inter-fascicular cambium (iii) overcomes apical dominance (iv) induces formation of new leaves, chloroplast and lateral shoots.
(ii) Vernalisation : Many species of biennials and perennials are induced to flower by low temperature exposure `(0^(@)C to 5^(@)C)`. This process is called vernalization. The term vernalization was first used by T.D. Lysenko (1938).
(iii) `P_(r)-` Phytochrome red (660 nm)
`P_("fr")-` Phytochrome far red (730 nm)