ROOT APPLICATIONS OF GIBBERELLIC-ACID ENHANCE GROWTH OF 7 PELARGONIUM CULTIVARS

Four concentrations of GA3 (0.05, 0.5, 5.0, or 50 mg.liter-1) were applied to the root systems of seven hydroponically grown geranium (Pelargonium x hortorum cv. Empress Irene, Glacier Crimson, Sincerity, Pink Fiat, Sybil Holmes, and Mrs. Parker and P. x domesticum cv. Lavender Grand Slam) cultivars. The relative growth rate of all cultivars tested increased with GA3 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 GA3 can stimulate growth over a wide range of cultivars. Chemical name used: gibberellic acid (GA3).