High temperature during imbibition of lettuce seeds can inhibit germination. Several methods to circumvent thermoinhibition and, or thermodormancy have been proposed including resistant germplasm, adjusting the seed production environment, the use of growth hormones and seed priming. The mechanism of action for each of these methodologies appears to be related specifically to endosperm loosening which allows the embryo to grow under high temperature. Endosperm loosening has been associated with the induction of endo-b-mannanase at the micropylar end. Ethylene may also play an important role in controlling this process.
Lactuca sativa; endosperm; enzyme activity; seed priming; stand establishment