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The Effects of SO 2 on in vitro Forest Tree Pollen Germination and Tube Elongation

1974; Wiley; Volume: 3; Issue: 4 Linguagem: Inglês

10.2134/jeq1974.00472425000300040024x

1537-2537

David F. Karnosky, G. R. Stairs,

Allergic Rhinitis and Sensitization

Abstract The effects of SO 2 on in vitro pollen germination and tube elongation were examined for Populus deltoides (Bartr.), Pinus resinosa (Ait.), Pinus nigra (Arnold), and Picea pungens (Engelm.). Comparisons were made between pollen fumigated in a dry condition and then placed on the germinating media, and moist pollen fumigated while on the germinating media. Moist P. deltoides pollen germination was significantly reduced at SO 2 concentrations of 0.75 ppm and above. Populus deltoides pollen tube elongation was more sensitive to SO 2 exposure and highly significant decreases in tube length occurred at 0.30 ppm for 4 hours. Tube elongation decreased linearly with increases in SO 2 concentration. Frequent bursting of pollen tubes occurred at SO 2 concentrations greater than or equal to 0.3 ppm for 4 hours. Exposure to SO 2 caused similar effects on pollen germination and tube elongation for Pinus resinosa, Pinus nigra , and Picea pungens . Moist pollen was far more sensitive than dry pollen to SO 2 exposure. A 4‐hour exposure to 1.4 ppm SO 2 severely restricted moist pollen germination and tube elongation of the three conifer species. However, a similar exposure to 10 ppm SO 2 had no effect on dry pollen of the three species. Absorption of SO 2 resulted in an acidification of the germination media. Germination trials on acidified media indicated that the resultant acidification could account for much of the reduced germination and tube elongation in P. deltoides but could not adequately explain the reduced conifer pollen germination and tube elongation.