Cold tolerance of lettuce

Lettuce seeds are capable of germinating at a temperature of 4–5 °C. Seedlings can withstand short-term temperature drops to –3…–5 °C, while mature plants in the vegetative phase can tolerate frosts down to –5 °C. With further temperature drops to –7…–10 °C, damage to the leaf apparatus occurs, although plants may retain the potential to resume growth.

Varieties that maintain growth and development rates in unheated greenhouses at night temperatures of 3–4 °C and daytime temperatures of 6–7 °C are considered cold-tolerant. The assessment of the trait is based on the biomass accumulation dynamics under stress conditions and the ability to reach market maturity within scheduled timeframes, which is confirmed by the analysis of metabolic markers and genes responsible for adaptation to oxidative stress.