Effects of Paclobutrazol on Growth and Flowering of Bougainvillea spectabilis WILLD

摘要

The effects of paclobutrazol were examined in respect to the growth and flowering of Bougainvillea spectabilis WILLD under conditions of long and short natural photoperiods. In the middle of July and at the beginning of November, doses of paclobutrazol; 0 (control), 10, 20, 30 and 50 mg a.e./pot soil drench, and 0 (control), 125, 250, 500 and 1000 ppm foliage spray, were applied to plants grown in 18 cm pots (h=16.5 cm). With the application of paclobutrazol in the form of soil drench and foliage spray, the time from application to flowering decreased slightly under the long photoperiod conditions but this effect did not occur under short photoperiod conditions. Paclobutrazol in the form of soil drench and foliage spray greatly decreased the length of shoots, decreased the number of flowers per plant and increased the number of shoots per plant even at the lowest doses and concentrations with both long and short photoperiods. It was found that the duration of growth suppression was greater when paclobutrazol was applied in the form of soil drench.