Nectar secretion dynamics in Nicotiana rustica
Nectar sampling of 23 Nicotiana rustica plants in a 15’ x 15’ garden plot located in Lamont, Alberta (53° 45' 35.7876'' N 112° 46' 38.712'' W) began August 5th, 2020 and took place every day, weathering permitting, until August 20th. Each day, buds on participating plants were bagged with 4" x 6" sheer drawstring pouches to exclude pollinators from the sample flowers. The selected buds were ones that appeared to be near-flowering, so that when eventually sampled they would be in anthesis (Figure 1). Each flower selected was sampled twice in a twelve-hour period, between 8:00 – 10:00 and 20:00 – 22:00. When the initial sample was taken (8:00 – 10:00 or 20:00 – 22:00) alternated each sampling round, so that the final samples of the entire data set would reflect both the nectar produced over the day and overnight. Only one flower/plant/round was sampled to reduce confusion. The initial sample period began by removing the exclusion bags and marking flowers in anthesis on each plant. Nectar samples were then collected from the newly opened flowers with 75 mm Drummond™ Capillary Tubes. The length of the nectar along the tube was measured with a ruler and recorded to be converted to a volume later. After this measurement the nectar was expelled from the microcapillary tube onto the sample well of a Fisherbrand™ Handheld Digital Brix/RI Refractometer, which had been previously zeroed and cleaned with distilled water. In a shaded area with the cover closed, the refractometer read off and produced the average of 15 Brix° measurements of each nectar sample (automatically correcting for temperature), and the number recorded. The sample well was cleaned, the flower re-bagged, and the process repeated for the next marked flower. These same flowers were then resampled 12 hours later using the same process, to determine the volume and Brix° concentration of the nectar produced between sample periods. Hypotheses: H0: Nicotiana rustica’s nectar attributes, including nectar volume (μl), weight of sugar present within the nectar (mg), or the nectar concentration (mg/μl), will not vary depending on the time of day it is secreted. Ha: One or more of Nicotiana rustica’s nectar attributes will vary depending on the time of day it is secreted.