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Bożena Denisow, Monika Strzałkowska-Abramek, Małgorzata Bożek and Anna Jeżak

Abstract

This study, conducted in 2008 and 2012 - 2013, evaluated the flowering pattern (seasonal and diurnal), the abundance of flowering, nectar, and pollen yield, and insect visitor activity for Corydalis solida (L.) Clairv. and C. cava Schweig. et Koerte. The populations occur in the ground layer of a deciduous forest (Fagetalia ordo, Querco-Fagetea class) in a natural gorge within the current area of the UMCS Botanical Garden in Lublin, Poland (51° 16’ N, 22° 30’ E). The phenology of Corydalis species showed distinct year-to-year plasticity (e.g., blooming period in March - April or in April - May; duration 18 - 42 days). The most intensive flower opening was noted in the early morning hours (85 - 90% of daily openings occurred between 6.00 and 10.00 h, GMT +2 h). The average sugar yield was similar at 4.6 kg/ha (C. cava) and 5.2 kg/ha (C. solida), but the average pollen production differed and reached 2.1 kg/ha (C. cava) and 4.1 kg/ha (C. solida). The flower-visitor interaction in Corydalis species involved both biological (early pattern of diurnal flowering, protandry, pollen presentation at the moment of anthesis) and morphological (nectar hidden in deep spur) features. Apis mellifera foragers predominated on both Corydalis species (mean of total visitors, 68.0% to C. solida; 62.5% to C. cava) and foraged mainly for pollen (82% of foragers), while bumblebee queens (mean of total visitors, 32.0% to C. solida; 37.5% to C. cava) collected mainly nectar (68.0% of foragers).

Open access

Bożena Denisow, Monika Strzałkowska-Abramek, Małgorzata Bożek and Anna Jeżak

Abstract

The flowering phenology and pollen production of three ornamental Centaurea species were investigated in the years 2009 and 2012-2013. The study objects, Centaurea montana L. = Cyanus montanus (L.) Hill, Centaurea mollis Waldst & Kit, and Centaurea dealbata Willd. were cultivated within an area of the UMCS Botanical Garden in Lublin, Poland (51° 14’ N, 22° 34’ E). Under the environmental conditions of SE Poland, the Centaurea species flowered continuously from mid-May to the first week of June. The mass of pollen in anthers was found to be species-related: 3.70 mg (C. montana), 4.02 mg (C. mollis), and 6.01 mg (C. dealbata) per 100 anthers. The total pollen yield was related to the mass of pollen produced in flowers and the abundance of blooming. Pollen grains were medium-sized, spheroid (C. dealbata) or prolato-spheroid (C. mollis and C. montana) in shape, and characterized by high viability (over 80% on average). The pollen provided by the plants of ornamental Centaurea species amounted to 6.0 - 7.9 g per m2 on average. The honeybee was the most frequent visitor of C. dealbata, accounting for 55.2% of the total pollinators, and bumblebee species predominated on the flowers of both C. montana (77.7%) and C. mollis (85.6%). Solitary bees and dipterans were also observed on the flowers of all species studied, but C. mollis was avoided by lepidopterans. Ornamental Centaurea species provide pollen reserves that could support communities of invertebrate pollinators, although the period of effective supply fluctuates annually due to changeable periods of blooming.