Question

Cabbage is a biennial plant which produces flowers in second year of growth. In an attempt to make it flower in a single year, four potted plants (I, II, III and IV) of cabbage were subjected to different temperatures for several days as given in the table.

$\begin{array}{cc}\text{Potted plant}& \text{Temperature}\\ \text{I}& 5^{\circ }C\\ \text{II}& {20}^{\circ }C\\ \text{III}& {30}^{\circ }C\\ \text{IV}& {25}^{\circ }C\end{array}$

Which potted plant will show flowering ?

• A. $I$
• B. $II$
• C. $III$
• D. $I$

Answer 1

The correct option is A $I$

In plants, flowering is either quantitatively or qualitatively dependent on exposure to low temperature which is known as vernalisation. The biennials plants complete their life cycle in two years as in cabbage, carrot, etc. They germinate and grow vegetative in first year and produce flowers in the second year of growth. These plants fulfill their cold requirement during winters. However, such biennial plants can be made to flower in one growing season by providing low temperature treatment (i.e., 0−5${}^{\circ }$C temperature) to young plants or moistened seeds. The low temperature required for vernalization is usually 0−5${}^{\circ }$C. So the correct answer is 'I'.