Fifty newly opened flowers from each of the experimental trees
were harvested at various times using different forceps for each
tree. The flowers were tied individually in nylon mesh and placed
in separate 1.5 ml Eppendorf tubes. The Eppendorf tubes containing
the experimental samples were introduced into a Retsch disrupter
for 1.4 min×2 at 25 cycles per second to separate the pollen grains
from the flowers through the nylon mesh. The nylon meshes containing
the flowers were removed and the Eppendorf tubes and
their contents (pollen grains)were stored at−22 ◦C for DNA extraction.