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