Effect of Various Growth-Regulating Substances upon Several Species of Plants

Abstract

1. Neither vitamin B1 nor naphthaleneacetic acid supplied to chrysanthemum plants in a concentration of 0.1 mg. per liter of complete nutrient solution produced any apparent growth responses or significant difference in dry weight. 2. Chrysanthemum plants receiving naphthaleneacetic acid in a concentration of 0.1 mg. per liter of minus K nutrient solution showed an increase in dry weight over the controls, indicating that the acid can compensate to some extent for the lack of potassium. 3. No significant difference in dry weight occurred between cosmos plants used as controls and those receiving 0.01 mg. of naphthaleneacetic acid, nicotinic acid, or nicotinic acid and vitamin B1 per liter of complete nutrient. 4. Marigold plants showed little variation in dry weight when supplied with nicotinic acid, or with a combination of nicotinic acid and vitamin B1. 5. A significant decrease in total dry weight of the marigold plants supplied with napthaleneacetic acid (0.01 mg. per liter) indicates a retarding effect of the acid on growth. 6. None of the treatments to which the cosmos and marigold plants were subjected resulted in visible effects upon their habit of growth or upon floral initiation.