Effects of Water Suspension and Wet-Dry Cycling on Fertility of Douglas-Fir Pollen

Studies were made to determine how long Douglas-fir pollen remains viable after suspension in cool water from 0 to 34 days. Linear regression analysis of in vivo and in vitro tests indicated that filled seed efficiency and pollen viability, respectively, decreased about 3 percent per day. The relation may have been nonlinear the first 6 days, as little decrease occurred during that time. An in vitro test of the effect of none, one, or two drying cycles on previously wetted pollens revealed a great decrease in pollen viability after just one drying cycle. The in vivo test of 1-, 2-, and 3-percent pollen suspensions showed that the 3-percent suspension resulted in 15 percent greater filled seed efficiency than the 2-percent and 57 percent greater than the 1-percent suspension.