| Summary: | This 3-year study examined the flowering phenology, to- tal floral display, nectar and pollen production as well as bee visitation to the ornamental shrub Deutzia x carnea (Lem.) Rehd.
D. x carnea bloomed from early June until the middle of July. The total flower display reached 47927 flowers per plant. The number of developed flowers strongly depended on weather conditions before and during the flowering period and fluctuated significantly during the years of study. The flower of D. x carnea lived 5 days and the persistence of an inflorescence was 11 days.
Nectar productivity per 10 flowers differed significantly between the years of study and ranged between 15.7 and
40.14 mg. Mean sugar content in nectar was 39.7%. The total sugar mass in nectar per 10 flowers averaged 9.91 mg (range:
3.81 – 18.91 mg). Pollen mass per 10 flowers was 16.89 mg. The estimated sugar and pollen productivity per plant was 36.8 g and
40 g, respectively.
Among bees (Apoidea), honey bees were principal visitors on Deutzia flowers. The peak of daily activity of honey bees and bumblebees occurred between 11.00 and 15.00 hrs, whereas the presence of other wild bees was noted in the morning and in the late afternoon. All bees gathered mainly nectar, but pollen collectors were also noted. The mean daily visiting rate was 0.0809 visits per flower × min-1.
The use of this shrub in gardens and parks should be encouraged in order to enrich food pasture for urban Apoidea. However, its cultivation is limited to areas of mild climate and adequate water supply.
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