Question

Some varieties of wheat are known as spring wheat while others are called winter wheat. Former variety is sown, and planted in spring and is harvested by the end of the same season. However, winter varieties, if planted in spring, fail to flower or produce mature grains within a span of a flowering season. Explain, why?

Answer 1

Spring variety:

The spring variety of wheat is sown in spring and flowers in summer. These varieties do not need exposure to low temperatures for flowering.



Winter variety:

The winter variety is sown in autumn so that the vegetative phase can go through the winter. The low temperatures help the variety to attain maturity before flowering. Flowering then happens in summer.



Vernalisation:

Vernalisation is the process of accelerating the flowering (quantitatively or qualitatively) in plants by exposing them to cold temperatures. The low temperature helps attain vegetative maturity before they produce flowers. It prevents precocious reproductive development at the end of the growing season permitting the plant to attain maturity.



Case-specific conclusion:

Winter varieties need cold treatment during winters to attain vegetative maturity before reproduction. Winter varieties, if planted in spring, fail to flower or produce mature grains within a span of a flowering season as they are not exposed to low temperature during winters which are essential for flowering. Hence, the absence of vernalisation is the reason behind the failure of flowering.