2.2 Manual control experiments
In order to obtain P. teres seeds from different sources, four
types of manual control experiments including nectar addition, natural
conditions, self and cross-pollination were conducted at the six study
sites during the anthesis of P. teres in two consecutive years
(2019-2020). All flowers at FG were selected to conduct nectar addition
experiments. Due to partially overlapped antheses and the same
pollinator of rewarding Thunbergia grandiflora and food-deceptiveP. teres , we mimicked the open flowers of T. grandiflorato produce artificial nectar. Spur of each newly-open flower of P.
teres was supplied with artificial nectar (20 μl volume and 50% sugar
content) and the surplus nectar was removed. Fresh nectar was re-added
using a microsyringe every morning at 08:00 am until the flower wilted.
Nectar addition did not result in floral damage and had no effect on the
floral longevity. So there was no necessity to set control of water
addition. In order to obtain natural fruit and seed set, all flowers and
inflorescences at AR, TSRA and VG were maintained in natural states. Two
flowers of each inflorescence at EPG and EMG were used to conduct self
(The pollinia were from the same or another flower in the same
inflorescence) and cross (The pollinia were from the other flower at
EPG) pollination, respectively. All flowers used in hand pollination
were bagged before the flowers opened and they were bagged again after
pollination. In next April, mature fruits of the four treatments were
collected for subsequent experiments.