ENVIRONMENTAL AND CHEMICAL EFFECTS ON CELERY (APIUM GRAVEOLENS L.) SEED PRODUCTION

Experiments were conducted over a 4-year period to compare the effects of chemical seed soaks with those of various parent plant treatments on the germination characteristics of celery seeds. All mother plants were raised in a glasshouse and during flowering and seed development were treated with growth regulator sprays, supplementary light high in red energy or/and had selected umbels removed.

Generally, umbel removal had little effect on the characteristics of the seeds on the remaining umbels whereas supplementary light delayed leaf senescence and seed ripening with consequent adverse effects on germination. Most growth regulator sprays reduced seed dormancy and improved germination under laboratory conditions but seedling emergence was not improved consistently in the glasshouse. In experiments where individual umbels were harvested, seeds from secondary and tertiary umbels gave higher percentage germination than those from primary and quaternary umbels. -Under commercial conditions, seedling production from seeds sown directly into peat blocks was best from seeds selected from secondary umbels or from non-selected seeds given a post-harvest soak with a mixture of the gibberellins A₄ and A₇ together with ethephon.