PRIMING OF LETTUCE SEED FOR EARLY AND UNIFORM EMERGENCE UNDER CONDITIONS OF ENVIRONMENTAL STRESS

Seed thermodormancy of some lettuce cultivars may be induced when they are imbibed at temperatures above 26°C. At temperatures above 35°, all lettuce cultivars are susceptible to thermodormancy.
Germination will not occur until temperatures are lowered below the "threshold" for a specific period of time.
In commercial production, high temperatures result in lack of uniformity, ultimately reducing yields.

Seed priming permits seed to imbibe water slowly, thus allowing germination to proceed at a regulated rate.
Primed seeds may be dried and planted with conventional machinery.
Experiments at the University of Florida have shown that thermodormancy in lettuce can be bypassed by seed priming in all cultivars tested to date.
Conditions for priming were similar for all cultivars with the exception of soak duration.
Seeds were primed in the dark in aerated solutions of 1% K₃PO₄ at 15°C for 9 to 22 hours.
Approximately 80% or more of the seeds germinated.
Under field conditions uniform stands were obtained from seeds that were primed and the crop was harvested earlier than from control treatments.
During the early portion of the season when soil temperatures were excessively high, stands could not be obtained unless the seeds were primed.

Symposium on Timing of Field Production of Vegetables

Daniel J. Cantliffe

https://doi.org/10.17660/ActaHortic.1981.122.3