Fruit weights, fruit set, seediness, and floral visitors of Nicotiana rustica

Published: 4 April 2022| Version 1 | DOI: 10.17632/jz95djmwrr.1
Kennedy Halvorson


Bagging Experiment: To determine if there was a difference between diurnal and nocturnal pollinators, the bagging experiment included four treatments: open (open both day and night), day open (bag removed during daytime), night open (bag removed during nighttime), and closed (no visitation). Flower buds were bagged using small mesh bags prior to anthesis to ensure no pollination had occurred prior to treatment (Reader, 1977; Kearns & Inouye, 1994; Usui et al. 2005; MacPhail & Kevan, 2007). Bags were made of Organza fabric and were 5 cm x 7 cm in size. Sunrise was between 4:39 AM and 4:55 AM during Round 1, and between 5:38 AM and 5:47 AM during Round 2. Sunset was between 19:24 PM and 19:43 PM during Round 1, and between 18:10 PM and 18:24 PM during Round 2. Bags were switched on the day open and night open treatments within 1 hour of the time of sunrise or sunset, coinciding with the changeover between diurnal and nocturnal pollinator activity (Bertin & Willson, 1979; Young, 2002.). The number of flowers on each branch was recorded every day throughout the experiment, and the number of pods developed was counted upon collection (Jennersten & Morse, 1991). Tobacco fruits were harvested once mature, approximately 21 days post-flowering (Rao & Rangaswamy, 1972; Sime & Baldwin, 2003). Reproductive success of the plants was determined by fruit set (number of fruits/number of flowers), fruit weight, and seediness (Usui et al. 2005; MacPhail & Kevan, 2007). Seediness was estimated by weighing all seeds from all pods in a sample, dividing this by the total number of pods to get an average mass of seeds per pod (g), and counting the number of seeds within a subset of the sample (0.05g). The number of seeds in the subset of the sample (0.05g) was then factored against the average mass of seeds per pod (g), giving an average seediness per pod. Insect Visitation Rate & Video Recordings: A time lapse video camera (Edwards et al. 2015) was used to record insect visitation (Kearns & Inouye, 1993). The camera was supported by a tripod and footage was recorded to a memory card. Floral visitations and behaviour (i.e. visitation rate) were determined by analysing video recordings (Kearns & Inouye, 1993; Edwards, 2015; Steen, 2017). Insects were tallied into the following categories: honeybee, bumblebee, small bee, fly, butterfly/moth, beetles, other, unless they could be identified to species (Kearns & Inouye, 1993; MacPhail & Kevan, 2007). Nocturnal recordings included dawn and dusk when there was some limited natural light available. Insects that landed on the outside of the flower were not included in analysis. Only insects that entered and contacted the reproductive parts of the flower were included. Video recordings occurred around the time of the bagging experiment: July 30-August 9 (Plot A), August 31-September 9 (Plot B), and August 18-August 25 (extra site).



York University


Plant Reproduction, Plant-Pollinator Relationship, Plant Ecology