Plant Growth and Development — BIOLOGY STD 11 Science — Question

Beside light, the temperature also affects the flowering and other vital phenomenon of plants. It has been observed that there are some plants which do not flower until they are not exposed to low temperature, i.e., they depend either qualitatively or quantitatively on exposure to low temperature to flower. This chilling requirement of the plants for flowering is known as vernalisation. It prevents the precocious reproductive development late in the growing season, enabling plant to have sufficient time to reach the level of maturity. Examples of Vernalisation:

1. Food plants like wheat, barley, rye has two types of food varieties.

1. Spring varieties: These are planted in spring and are normally come to flower and produce grain before the end of same growing season.
2. Winter varieties: These are planted in autumn season If they are planted in spring season they would fail to flower or produce a mature grain within a span of flowering season. Thus, winter variety germinated in winter remains as seedling, resumes growth in the spring and are harvested by mid-summer.

2. Similarly the same process ofvernalisation is observed in another varieties, like biennial plants, which are monocarpic in nature that usually flower and die in second season. if these biennial plants are subjected to a cold treatment thus, stimulate subsequent photoperiodic flowering response.