I do not have access to the following article:
Application of oils in refining of apple pollen. Ueta, Authors: Jun-etsu; Morita, Izumi.
Authors affiliation: Akita Prefectural Technical Center of Agriculture, Forestry and Fishery, Japan.
Published in: Nogyo oyobi Engei (2007), 82(6), pages 667-670. Written in Japanese.
Abstract: “A review on the application of the solvent pollination method by using oils as the solvent for purifn. of pollen which is superior to that of using the org. solvents. The recovery, storage stability, and pollination capability of pollen purified by oil and org. solvent was also compared.”
Howver, I was able to access the full paper of “Storage of Pollen Grains of Crotalaria retusa in Oils”:
http://www.springerlink.com/content/q33j666578t8l06w/
Of particular interest is that at 180 days storage oil storage did not decrease pollen tube length while organic solvent storage did (at -20 degrees C).
Also, room temperature storage (for dried pollen) was 15 days, but for n-hexane and the tested olis the pollen had good germination for 30 days and “even at 60 days a small proportion of the pollen grains showed germination”.
Quote from page 226: “In all of the pollen samples stored at the laboratory temperature, the reduction in tube growth was apparent much earlier than the reduction in percentage germination; however, the reduction in tube length in samples stored in oils was significantly less than those stored at low relative humidity or in n-hexane (Table 1).”
In Table 1:
At 30 days the tube length for low humidity was 108 microns (4% germination), for n-hexane it was 166 (71% germination), for paraffin oil it was 372 (84% germination), for soybean oil it was 365 (72% germination), and for olive oil it was 332 75% germination).
At 45 days the corresponding numbers are: zero (no germination), 163 (49% germination), 247 (43% germination), 283 (55% germination), and 255 (40% germination).
At 60 days the corresponding numbers are: zero (no germination), 73 (8% germination), 150 (18% germination), 148 (12% germination), and 109 (3% germination).