Viability Tests to Evaluate Pollen Reliability in Loblolly Pine Controlled Pollinations

Ultraviolet absorbance and conductivity of loblolly pine ( Pinus taeda L.) pollen leachate were both significantly and negatively correlated with in vitro germinability of 11 stored pollen lots. The absorbance and conductivity tests, repeated on two dates, were very strongly correlated. The in vitro pollen germinability test repeated on three dates were not consistently repeatable. For each of the tests, a simple linear regression equation was developed using the pollen viability values to predict the average number of seeds produced per flower pollinated. Each of the regressions was significant and had approximately the same precision. Forty-five minutes were required to test a pollen sample using the conductivity or absorbance test and 48 hours were required to test a pollen sample using a 0.01 percent honey solution. Great savings in time, highly repeatable results, and precision similar to the traditional germination technique lead the authors to prefer conductivity and absorbance for future pollen testing. Forest Sci. 25:270-274.