Pollen germination and hand pollination in pitaya (Selenicereus spp.)

Abstract

Hand pollination is a necessary assisting method for pitaya (Selenicereus spp.) production to achieve a high yield. With the cultivated
area increasing at an exponential rate in recent years, a comprehensive study of the pollination process was conducted. We developed
an ideal medium for pitaya pollen in vitro germination in this study, then tested the activity of pollen collected from or stored for various
time periods. We discovered that those collected between 2 h before blooming and 6 h after blooming had the higher germination rates
(27.2–65.1%), the highest activity was at 2 h after blooming, and that storing them at 4°C for 24 hours reduces their germination rate
from 65.2 percent to 35.5 percent and their production to about 82%. As a result, pollinating plants with pollen that has been held for
more than 24 hours is not recommended unless a breakthrough in pollen storage is achieved. We also discovered that stigma receptivity
and pollen activity are synchronized, which together determines the rate of fruit setting and the size of the fruit. Pollination within 6
hours after flowering offers the optimum fruit setting percentage and size, while pollination at 6:00 pm, 2 hours before blooming, is
also a good alternative; however, pollination at 6:00 am the next morning is expected to result in a 23 % drop in productivity. These
findings will be beneficial for reproductive biology research, as well as laying the groundwork for hand pollination to boost pitaya output
and breeding efficiency.