469 Some Citrus Flower Characteristics Limit Bee Preference of Hybrids and Their Pollination

in HortScience
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  • 1 University of Florida, Citrus Research and Education Center, Lake Alfred, FL 33580

Except for `Orlando' and `Minneola' tangelos, most citrus hybrids grown in Florida are small-flowered and produced less than half the nectar of large-flowered cultivars. Sugar contents in large- and small-flowered cultivars were not different in 1997, but the concentration of sugars doubled in 1998 over 1997 for small-flowered hybrids, while nectar volume was about one-half of that in the previous year. Nectar volume of large-flowered cultivars increased slightly in 1998 compared to 1997. Of four aromatic volatiles measured from headspace over flowers, `Robinson' and `Ambersweet' were lowest in total while other cultivars had only some specific differences. Grapefruit flowers produced high limonene levels, while `Sunburst', `Fallglo', and `Valencia' gave off the most myrcene. Bees were tested for flower preference in a round, white screenhouse using a mini-hive and duplicated fresh-cut flower bouquets each day. Bees preferred large-flowered cultivars with more nectar. Some other preferences also were observed. In the field, hedge-rows limited cross movement of bees in mature blocks of hybrids, which limits the number of contiguous rows of the preferred cultivar for good pollinization. Timing of bee hive placement was also critical to get bee movement into the intended block because flowering times differ for some cultivars and bees develop inital preferences.

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