Varietal Differences in Light Requirements for Germination of Celery (Apium graveolens L.) Seeds and the Effects of Thermal and Solute Stress

Abstract

Seed germination in one wild and two cultivated varieties of celery (Apium graveolens L.) was found to be light-dependent and mediated through the phytochrome system. Seeds of cv. Florida at 20°C were very sensitive to light and germination could be promoted by green safe light as well as by short far-red irradiation of brief duration, while seeds of wild celery did not respond to far-red and were less responsive to green safe light. At the optimal temperature, continuous irradiation with white light caused maximal germination in all varieties. The need for light could be satisfied in cv. Florida by two daily short irradiations. In wild celery, more than six short irradiations were needed, while in cv. Alabaster short irradiations did not bring about the full light effect. Daily alternating temperatures also could replace the light requirement. Two varieties, cv. Florida and the wild, differ in their tolerance to high temperature. Seed germination of wild celery is more thermophilic than that of cv. Florida. Thermodormancy is induced by 35°C of shorter duration in seeds of cv. Florida than in those of wild celery. Light enhanced the induction of thermodormancy. Solute stress increased the number of short irradiations required for germination.

Comparison of the seed germination of native and non‐native winter annual Apiaceae in North America, with particular focus onCyclospermum leptophyllumnaturalized from South America

“…Seeds of Apium graveolens required light for germination, but this requirement was highly dependent on temperature, with germination in darkness decreasing as temperatures increased (Thomas et al . 1975; Pressman et al . 1977).…”

“…1975; Jacobsen et al . 1976; Pressman et al . 1977, 1988; Biddington & Thomas 1979; Jacobsen & Pressman 1979; Coolbear et al .…”

Germination of seeds of annual and biennial celery (Apium graveolens)

“…Celery {Apium graveotens L.) is usually a biennial plant. In its first year the plant produces a rosette type shoot and in the second year, after exposure to low temperatures during the winter, it bolts and flowers (Pressman and Sachs 1985). However, 4 cultivars of celery obtained from Taiwan and Thailand are all annuals.…”

“…These showed that celery seeds generally require light for germination (Robinson 1954). Under low temperature conditions (10-15°C) some varieties germinate in the dark (Morinaga 1926, Taylor 1949, while others do not (Pressman et al 1977). Alternating temperatures can substitute for the requirement for light (Morinaga 1926(Morinaga , T-hompson 1974.…”

“…Alternating temperatures can substitute for the requirement for light (Morinaga 1926(Morinaga , T-hompson 1974. At 30°C germination is poor even under continuous light, and at higher temperatures the seeds undergo secondary dormancy (Morinaga 1926, Pressman et al 1977, Biddington and Thomas 1979. Solute stresses, such as diluted sea water or NaCl solutions inhibit the germination of cv.…”