Application of Growth-Regulating Substance in Aerosol Form, with Special Reference to Fruit-Set in Tomato

A recently developed aerosol method of applying growth-regulating substances to tomatoes has proved an effective means of inducing fruit setting and,in many cases, of producing seedless fruits. 2. 4-Chlorophenoxyacetic, β-naphthoxyacetic, indoleacetic, indolebutyric, and a-napthaleneacetic acids differed in their capacities to induce fruit-set. Of these, 4-chlorophenoxyacetic acid was the most effective in setting fruit and stimulating early fruit growth. When used at concentrations higher than 0.01%, the treated plants developed abnormal leaves and fruits. 3. β-naphthoxyacetic acid also induced setting of seedless tomatoes when applied as an aerosol. The safest and still effective range of concentration lies between 0.01 and 0.5%. Not all the fruits from treated flowers were seedless. Apparently their age and the amount of pollination determined to some extent the amount of seed development, but early fruit growth was greatly stimulated. 4. Indoleacetic, indolebutyric, and a-naphthaleneacetic acids were less effective than the other compounds in inducing fruit-set and producing seedless fruit when applied by this aerosol method.