Investigating Vernalisation & Creating Genetic Crosses

Certain plants require a cold spell in their life cycle to initiate the sequence of events that leads to flowering. The term vernalisation is used to describe the promotion of flowering by exposure of young plants to cold temperatures. It is effective on seeds that have taken in water or on a growing plant, but not on dry seeds. The necessary ‘chilling’ treatment may be for only a few days but often several weeks are required. The vernalisation requirement is associated with species found growing in regions with winter temperatures that are unsuitable for plant growth. You can see the disadvantage to the plant of premature germination and growth (at the end of the summer season) before the cold winter season.

Vernalisation offers an interesting example of the way that plants have evolved to exploit the predictability of seasonal change and, in this case, to ensure that flowering occurs at an appropriate time. It also gives an example of how environmental factors control and interact with different stages in the life cycle.

This sheet describes the process of vernalisation and how it can be done to help induce flowering in Chinese cabbages. You can then use the resultant plants to carry out genetic crosses with rapid cycling brassicas.