Effects of fluoride on pollen germination and pollen tube growth. [Tomatoes]

Tomato plants continuously exposed in atmospheres having 5 ..mu..g or more of F/m/sup 3/, as HF, produced smaller fruits or fruits with fewer seeds, or both, than similar control plants. Such treatment reduced pollen germination and subsequent pollen tube growth. Pistils of self- and manually pollinated flowers (the latter emasculated when flowers were fully open) were removed 2 to 10 days after pollination, stained with aniline blue, and observed under UV light. The amount of pollen on the stigma, per cent of grains which germinated, number of tubes growing to the base of the style, and number of tubes reaching ovules were determined. Pollen from HF-exposed plants had lower germination percentages in vitro than pollen of the controls. Less pronounced results were obtained in cross pollinations (both pollen of controls to HF exposed and the reciprocal), suggesting that the F affected both the male and female parts of the flower. Inhibition of germination and tube growth appears to be proportionately related to the concentration of the F; however, the degree of the F effect can be partially regulated by the amount of Ca within the nutrient solution or media.