Abstract
The applicability of spray pollination for Cryptomeria japonica in the field, as an artificial pollination promotion
technique, was examined to effectively utilize a small amount of pollen while improving workability. First, the effect
of storage time of the pollen grain-water suspension on pollen activity was evaluated. Pollen grains stored for 12 h in
the suspension had a similar germination activity to those evaluated immediately after the suspension was prepared.
Then, spray pollination with three levels of pollen concentrations (0.2%, 0.5%, and 1.0%) on multiple mother tree
clones with female strobili at different developmental stages (start, half-open, and full-open) was tested. In addition,
to evaluate whether mating following spray pollination was successful, the seedlings grown from the collected seeds
were subjected to paternity analysis using DNA markers. There was no effect by spray pollination on the levels of
cone yield and the 100-seed weight (p > 0.05). Conversely, spray pollination at 1.0% pollen concentration had a
significant positive effect on the seed germination rate (p < 0.05). Spray pollination at the two pollen concentrations
of 0.5% and 1.0% had a significant positive effect on the ratio of seedlings (mating success rate) for the spray pollen
used (p < 0.05 and p < 0.01, respectively). The mating success rate with the 1.0% pollen concentration was higher
than that with the 0.5% concentration. Among the three female strobili developmental stages, the mating success rate
tended to be higher when spray pollination was performed at the half-open stage. A mating success rate of 0.362 was
predicted using a spray pollination with 1.0% at the half-open stage of strobili. In summary, spray pollination was
shown to have beneficial effects on mating even in the field.
