What is vernalization?

• A. A warm period that ensures rapid growth
• B. A photoperiod cue for flowering
• C. A required chilling period that makes some plants flower or break dormancy
• D. A drought stress period

Answer: (C)

Vernalization is a period of prolonged cold that a plant must experience to enable flowering or to break dormancy. This cold exposure acts as a developmental signal, not a boost from warmth, so it doesn’t make plants grow faster. Instead, it reprograms the plant’s flowering pathway so that when temperatures rise and day length becomes favorable, the plant can proceed to flower. Many winter annuals and biennials, like those in the cabbage family and other temperate crops, rely on vernalization to ensure they don’t start flowering before winter ends. The cold often works by quieting flowering inhibitors, allowing flowering-promoting processes to proceed after winter. This is different from a photoperiod cue, which depends on day length, and from drought or heat stresses, which are unrelated triggers for flowering in these species. Some plants do not require vernalization and flower in response to photoperiod or other signals instead.