Impact of enhanced ultraviolet-B radiation on flower, pollen, and nectar production

Publication Type:Journal Article
Year of Publication:1999
Authors:B. J. Sampson, Cane J. H.
Journal:American Journal of Botany
Volume:86
Pagination:108 - 114
Date Published:1999///
Keywords:CLIMATE, COMPETITION, FLORAL DISPLAY, FLORAL REWARDS-NECTAR, FLORAL REWARDS-POLLEN, FLORAL TRAITS, FLORAL TRAITS-SIZE, FLOWER NUMBER, FLOWERING, HUMIDITY, HYDROPHYLLACEAE, NECTAR SECRETION, OSMIA, PHENOLOGY, POLLEN, POLLEN PRODUCTION, POLLINATION, POLLINATOR, REPRODUCTION, SUGAR, ULTRAVIOLET, WEATHER
Abstract:

Intensified ultraviolet-B radiation or UV-B (wavelengths between 280 and 320 nm) can delay flowering and diminish lifetime flower production in a few plants. Here we studied the effects of enhanced UV-B on floral traits crucial to pollination and pollinator reproduction. We observed simultaneous flowering responses of a new crop plant, Limnanthes alba (Limnathaceae), and a wildflower Phacelia campanularia (Hydrophyllaceae), to five lifetime UV-B dosages ranging between 2.74 and 15.93 kJ.m(-2).d(-1), Floral traits known to link plant pollination with bee host preference, host fidelity and larval development were measured. Intensified UV-B had no overall effect on nectar and pollen production of L. alba and P. campanularia flowers. A quadratic relationship between UV-B and nectar sugar production occurred in P. campanularia and showed that even subambient UV-B dosages can be deleterious for a floral trait. Other floral responses to UV-B were more dramatic and idiosyncratic. As UV-B dosage increased, L. alba plants were less likely to flower, but suffered no delays in flowering or reductions to lifetime flower production for those that did Bower. Conversely, an equal proportion of P. campanularia plants flowered under all UV-B treatments, but these same plants experienced delayed onset to bloom and produced fewer flowers at greater UV-B intensities. Therefore, intensified UV-B elicits idiosyncratic responses in flowering phenology and flower production from these two annual plants. Diurnal patterns in nectar and pollen production strongly coincided with fluctuating humidity and only weakly with UV-B dosage. Overall, our results indicated that intensified UVB can alter some flowering traits that impinge upon plant competition for pollinator services, as well as plant and pollinator reproductive success

Taxonomic name: 
Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith