Flowering spurs located at interior and exterior canopy positions of `Stay-man' and `Delicious' apple (Malus domestics Borkh.) trees were girdled and/or defoliated to determine the influence on nectar production and composition. Nectar volume was less at exterior than interior canopy positions for `Delicious', but not for `Stayman'. Girdling suppressed nectar production by 92% and reduced the sugar concentration of the remaining nectar. Defoliation of nongirdled spurs had no effect on nectar sugar concentration, but defoliation of girdled spurs reduced nectar sugar concentration by 24%. Relative percentages of sucrose, glucose, and fructose, and the sucrose: hexose ratio were unaffected by any treatment. Nectar production of nongirdled spurs did not depend on the presence of spur leaves.
Richard J. Campbell, Richard D. Fell, and Richard P. Marini
Erin M. Silva, Bill B. Dean, and Larry Hiller
Successful pollination of onion (Allium cepa L.) flowers greatly depends on adequate nectar production. In order to understand the nectar production dynamics of onion flowers, nectar was collected at regular intervals during a 24-hour period. Hourly nectar volumes were compared to a variety of environmental conditions, including amount of solar radiation, relative humidity, temperature, wind speed, and evapotranspiration. Production patterns showed mid- to late-morning peaks and late evening peaks in nectar volume. Nectar appeared to be reabsorbed by the flowers during the afternoon and overnight hours. Individual flowers produced the highest amount of nectar several days after initially opening. Nectar production was significantly and inversely related to relative humidity while the effects of temperature, evapotranspiration, wind speed and solar radiation on nectar production were not significant in this study.
James H. Cane and Daniel Schiffhauer
Cranberry flowers (Vaccinium macrocarpon Ait.) require bee visitation for pollination. Bees visit cranberry flowers for nectar and sometimes pollen, but honey bees (Apis mellifera L.) in particular often work alternative co-flowering species for nectar, presumably because cranberry offers inferior nectar rewards. In a common garden setting, replicated plots of the cultivar Stevens were found to secrete significantly more nectar sugar (25% to 35% more) per flower than either `Ben Lear' or `Early Black', two other common commercial cultivars. The nectar secretion rate of `Stevens' was unaffected by a 4-fold range of fertilizer application rates over the preceding 2 years. These results are compared to studies of other crops involving varietal differences and programs of selective breeding for nectar secretion.
S. Wolf, Y. Lensky, and N. Paldi
Fruit and seed set in insect-pollinated agricultural crops rely primarily on honeybees because of their ease of management and transportation. In many fruit and vegetable crops, the number of bee visitations can be the limiting step in obtaining optimal yield. Increasing the attractiveness of flowers to honeybees could, therefore, provide a useful means of improving fruit yield and seed production. Genetic variability in attractiveness to honeybees was found within the genus Citrullus. The number of daily visits per flower ranged from six to 12 among cultivars. Moreover, most of the visits to the more attractive cultivars occurred in the first hour of bee activity, whereas visits to the less attractive cultivars started later in the morning. A positive relationship was found between the frequency of bee visitations and seed number per fruit. Analyses of floral attributes indicated no genetic variability in flower size, amount of pollen grains, or nectar volume; however, differences were observed in the concentration of sucrose and total sugars in the nectar. A positive relationship was found between attractiveness to bees and nectar sugar concentration, suggesting that this characteristic is one of the parameters responsible for variability in attractiveness to honeybees.
Raphael A. Stern and Shmuel Gazit
Pollination of lychee (Litchi chinensis Sonn.) by the honeybee was studied in Israel's two commercial cultivars, `Mauritius' and `Floridian'. Pollination rate, which was determined in a mixed `Mauritius' and `Floridian' plot, followed a consistent pattern: it was low at the first male (M,) `Mauritius' bloom and reached a high value only when the pseudohermaphroditic (M2) `Mauritius' bloom started. Pollen density on bees collected from `Mauritius' inflorescences was very low during the M, bloom and increased to very high values during the M2 bloom. These results indicate that the `Mauritius' M, bloom does not play an important role as a source of pollen for pollination. Pronounced, significant, and consistent differences in nectar volume per flower and sugar concentration in the nectar were found between M1, M2, and female (F) `Mauritius' flowers. Values were very high in F flowers, medium in M2 flowers, and low in M, flowers. Accordingly, the density of bees found on inflorescences was high during the F bloom, intermediate during the M2 bloom, and low during the M1 bloom. The positive correlation between bee density and sugar concentration in the nectar was highly significant for M2 and F `Mauritius' flowers. The nectar contained three sugars: glucose (43%), fructose (39%), and sucrose (18 %). This ratio was the same in nectar from M1, M2, and F `Mauritius' flowers.
Patrick P. Moore
W. David Lane, M. Meheriuk, and R.A. MacDonald
Melissa Broussard, Sujaya Rao, William P. Stephen, and Linda White
Schiffhauer, 2001 ; King and Buchmann, 2003 ; MacKenzie, 1994 ), although some pollen transfer may still occur while foraging for pollen and/or nectar. Additionally, the number of available hives has decreased with recent threats to honeybee health such as
Ian G. Lane, James Wolfin, Eric Watkins, and Marla Spivak
et al., 2017 ). One of the primary methods of conserving pollinators is through the addition of forbs that provide pollen and nectar resources in the landscape ( Murray et al., 2009 ). This method has proven effective in increasing pollinator
Carter M. Westerhold, Samuel Wortman, Kim Todd, and Douglas Golick
pollinating plants?” open response answers were provided by participants. Out of a possible knowledge score of three, the mean knowledge score was 2.44 (±0.59). The benefits of food represented 35% of the responses; of these, nectar was specifically mentioned