How is artificial supplementary pollination carried out for dawn redwood (Metasequoia glyptostroboides)?

The artificial supplementary pollination method for dawn redwood (Metasequoia glyptostroboides) is: the dawn redwood has unisexual flowers and is monoecious; when the male cones turn from green to yellow, select individual trees that are robust and bear many inflorescences, pick inflorescences with branches and cultivate them indoors to collect pollen. Cut the flowering branches into lengths of about 20 cm, whittle the base into a straight cross-sectional cut, tie every 20 to 30 branches into 1 bundle, align the bases of the branches, attach 1 ball of absorbent cotton soaked in nutrient solution to the cut surface of the branches, wrap the outside of the cotton ball with plastic film (to prevent the nutrient solution from evaporating), hang the bundled inflorescences indoors, lay white glossy paper beneath them to catch the pollen, use a syringe to inject an appropriate amount of nutrient solution into the absorbent cotton ball every 6 to 8 hours, and regulate the development speed of the inflorescences by controlling the indoor temperature, so that the pollen-shedding time of the male inflorescences coincides with the development of the female flowers outside. Before pollination, place the small bundles of male flowers in a dry, clean plastic bag and shake them, and a large amount of pollen will be shed. Artificial supplementary pollination: after selecting the pollinated mother trees well, pay attention to observing the development of the female flowers in order to choose the best pollination timing; carry out pollination when the vast majority of female flowers have opened and the ovules have extruded pollination drops. Mix every 5 to 10 grams of the collected pollen with 50 grams of talcum powder, put it into a silk or fine nylon cloth bag, tie it to the tip of a long pole, and shake it inside and outside the crown of the selected mother trees to achieve the purpose of pollination.