Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
Vernalisation is the process where flowering is either quantitatively or qualitatively dependent on exposure to low temperatures ( to ).
The term was coined by T.D. Lysenko to describe the promotion of flowering by a period of low temperature.
It prevents precocious reproductive development late in the growing season, ensuring the plant has reached sufficient maturity before flowering.
The site of perception for the cold stimulus is the shoot apex, embryo of the seed, or active meristematic regions.
Vernalisation is often seen in winter varieties of cereal plants like wheat, barley, and rye, which are planted in autumn and harvested the following summer.
Biennial plants, such as sugarbeet (), cabbage, and carrot, are monocarpic plants that require a cold period to transition from vegetative growth to flowering in their second season.
The process involves a hypothetical hormone called 'Vernalin', which is believed to be transmitted from the site of perception to other parts of the plant.
📐Formulae
💡Examples
Problem 1:
Contrast the planting and flowering cycles of 'Spring' and 'Winter' varieties of wheat ().
Solution:
Spring varieties are planted in the spring and flower/produce grain before the end of the same growing season. Winter varieties, if planted in spring, fail to flower. They must be planted in autumn, survive the winter at low temperatures (), and then resume growth in spring to flower in summer.
Explanation:
The winter variety has an obligate requirement for vernalisation during the cold winter months to induce the physiological change necessary for flowering.
Problem 2:
Explain what happens when a biennial plant like a carrot is kept in a tropical climate without a winter season.
Solution:
The carrot plant will continue to grow vegetatively, producing only leaves and a thickened root, but it will fail to 'bolt' (produce a flowering stalk) and produce seeds.
Explanation:
Biennials require a period of low temperature exposure to trigger the transition from the vegetative phase to the reproductive phase. Without this cold stimulus, the synthesis of does not occur.