Response of Tomato Fruiting to Hydrogen Fluoride as Influenced by Calcium Nutrition

Two varieties of tomatoes grown at 40 to 200 ppm calcium were continuously fumigated with HF throughout flowering and fruit development. Fruit size was directly related to the level of calcium nutrition, and within each calcium treatment the fruits on plants subjected to HF at about 6 μg F/m³ were smaller than those on unfumigated plants. The smaller fruit size was associated with partial or complete seedlessness, suggesting that calcium plays an essential role in fertilization with which fluoride may interfere. Fluoride injury to the tomato foliage was most severe at the lowest calcium level. Treatment with HF at about 8 μg F/m³ produced some injury to tomato foliage but had no apparent effect on fruiting. Evidently fluoride can affect plant fruiting, but considering the severity of the HF treatments required, effects on tomato fruiting probably are of little practical significance. The relationship between fluoride injury and calcium nutrition suggests interference with calcium metabolism as a mechanism of fluoride injury to plants.