Variety traits

Heat tolerance of lettuce

Lactuca sativa L.

Heat tolerance of lettuce (thermotolerance) is the plant's ability to maintain normal growth and development at temperatures above 25–30 °C, preventing bolting and physiological leaf damage.

In the reference 7 varieties crop Lettuce, where this is mentioned in the description.

Evaluation of lettuce heat tolerance includes laboratory analysis of seed thermoinhibition by calculating the thermoinhibition coefficient, which is the ratio of germination at 30 °C to germination at 25 °C. Varieties with a high coefficient, close to unity, are considered the most thermotolerant. Physiological indicators such as mean germination time, chlorophyll fluorescence, and proline accumulation are also used.

In field and greenhouse conditions, resistance is determined by visual symptoms: the presence of tipburn, which is caused by disrupted calcium transport, and premature bolting. Important markers also include morphological changes, such as internode elongation and leaf blade deformation, which, in combination with damage scoring scales, allow for the assessment of the commercial suitability of varieties under heat stress conditions.

General information about the subject — on the page Heat tolerance.

Sources8

Varieties of Lettuce mentioned in the description

Selection based on the description text, not on official evaluation: these data are absent from registers. For specific variety details, please refer to its profile.