Root Applications of Gibberellic Acid Enhance Growth of Seven Pelargonium Cultivars

Four concentrations of GA, (0.05, 0.5, 5.0, or 50 mg·liter –1 ) were applied to the root systems of seven hydroponically grown geranium (Pelargonium × hortorum cv . Empress Irene, Glacier Crimson, Sincerity, Pink Fiat, Sybil Holmes, and Mrs. Parker and P. × domesticum cv . Lavender Grand Slam) cultivars. The relative growth rate of all cultivars tested increased with GA 3 treatments. In conjunction with the increase in growth rate, each of the cultivars showed a reduction in the root: shoot ratio and chlorophyll content per unit leaf area with no change in the percent moisture. These Pelargonium cultivars are genetically diverse, showing that GA 3 can stimulate growth over a wide range of cultivars. Chemical name used: gibberellic acid (GA 3 ).