Nectar production of some plum cultivars

Nectar production and anther dehiscence of four plum cultivars were studied in a Hungarian plant cultivar collection, from 9 to 18 o'clock hourly, from the beginning of bloom until the end of flowering in spring 2001. The aim of the study was to determine if there was any relation between floral biological type and nectar production rhythm. Both studied self-sterile cultivars were delayed homogamous and both studied self-fertile cultivars were delayed autogamous. Nectar production depended on the stage of blossoming and the periodicity of the secretion, but it could be influenced also by weather conditions. Nectar secretion was reduced at the beginning of flowering. In full bloom the quantity of nectar was measurable and anther dehiscence began in the afternoon. At the end of flowering, nectar secretion and anther dehiscence became continuous. In full bloom the protogynous phase flowers of the self-sterile 'Sermina' and 'Sotetkek tojas' produced nectar with one production maximum, which indicated 12-hour rhytmicity. However, homogamous phase flowers secreted nectar with two production peaks, which indicated 6-hour periodicity. In the self-fertile 'Deli Vengerka' and 'Orias' nectar secretion was insignificant, anther dehiscence became continuous.