Effect of high-temperature stress on the growth and seed characteristics of barley and cotton.
The existence of a sensitivity gradient to a uniform high-temperature stress applied at stages during seed maturation can be demonstrated in barley. The germination of freshly harvested seed is depressed following heat stress at 7--10 days after awn emergence, but is enhanced by the same stress applied 3 weeks after awn emergence. The depression is attributed to reduced viability associated with thermal injury. The stimulation following stress at more mature stages of seed development is related to a thinner seed coat, increased permeability as evidenced by faster imbibition rate, and decreased content of water-soluble inhibitors in the seed. These effects of environmental stress during seed maturation aid in explaining differences noted in the germinability at harvest of seed produced in successive years or produced in the same year at different locations. Seed of American Cotton, var. AC 134, was stressed at 50 degrees, 60 degrees, 70 degrees, 80 degrees, and 90 degrees C for 24 or 48 h before seeding. Stresses at 50 degrees to 70 degrees C increased seedling emergence and subsequent performance of the cotton plants, but higher temperatures caused thermal injury or killed the seed.
D002523:Edible Grain / Q000502:physiology*; D003368:Gossypium / Q000254:growth & development / Q000502:physiology*; D001467:Hordeum / Q000254:growth & development / Q000502:physiology*; D006358:Hot Temperature; D012098:Reproduction; D012639:Seeds