Journal of Apicultural Science

The structure of nectaries and nectar secretion in common pear (Pyrus communis L.)

Journal of Apicultural Science. Volume 49, Issue 1, Pages 85-92, ISSN (Print) 1643-4439
The structure of nectaries of Pyrus communis was examined under light (LM) and scanning electron (SEM) microscopes. The nectar from pear blossom was collected with the pipettes methods and the sugar content in the nectar was determined refractometrically. Situated at the upper part of the floral receptacle, the nectaries of common pear were equally thick along their whole length. Small cells of the secretory tissue, with thick cytoplasm, made up a thick multi-layer which did not have any contact with the vascular tissue. Observations under SEM revealed that the cells of the above-nectary surface were covered with a thick cuticle with distinct lines, while the cuticle covering the nectary was relatively thin and smooth. The nectary epidermis cells were usually polygonal in shape. Numerous open stomata, throughout nectar is secreted, were situated on the bottom of hollows of considerable size. Around the stomata, dried nectar was observed of various shapes and forms. Nectar was secreted for three days. The average amount of the secreted nectar was 2.47 mg with the concentration of sugar of 12.8%. It seems that the location of nectaries in a flower and dilute, quickly drying nectar are the reasons for the low attractiveness of pear flowers to pollinators.
Pyrus communis, nectary structure, nectar secretion
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