EFFICIENCY OF VARIOUS INSECTS IN GERMPLASM REGENERATION OF CARROT, ONION AND TURNIP RAPE ACCESSIONS

Seed regeneration is one of the most important tasks in genebank work. To regenerate germplasm of allogamous, entomophilous plant species in isolation facilities, insects are often used as pollen vectors. The o bjective of this study was to determine the effect of pollinator speci es, pollinator densities, pollinator combinations, and flower preferen ces on the seed quantity and quality of Daucus carota, Allium cepa, an d Brassica rapa. The isozyme phosphoglucoisomerase (PGI) served as gen etic marker in determining outcrossing rates and pollen dispersal dist ances. Field plots and isolation cages without insects were used as co ntrols. The pollinators studied consisted of the following insect spec ies from German native fauna: red mason bees (Osmin rufa L.), hoverfli es (Eristalis tenax L.), and blowflies (Calliphora sp. and Lucilia sp. ). In D. carota and B. rapa, higher seed yields were achieved in isola tion cages than in field plots, but in A. cepa lower seed yields were obtained in the isolation cages. Although O. rufa showed no liking for A. cepa, unintentional pollination was effected by this insect in iso lation cages. Lower insect densities were necessary for O. rufa than f or the various fly species.