Effect of Growth Retardants on Production of Containerized `Barbara Karst' Bougainvillea
in HortScienceThe effect of four PGRs on production of `Barbara Karst' bougainvillea [Bougainvillea × buttiana (Bougainvillea glabra Choicy × Bougainvillea peruviana Humb. & Bonpl.) was determined. Liners were transplanted into 3.8-L containers with a soilless substrate on 6 Apr. 1995 and were pruned on 15 May (mean height and width 23.6 and 34.5 cm, respectively). Uniconazole (10 ppm), maleic hydrazide (2808 ppm), daminozide (5000 ppm), and paclobutrazol (50, 100, or 200 ppm) were applied as a foliar spray (to wet) by a compressed air backpack sprayer on 16 May (0 weeks after treatment [WAT]). Daminozide (5000 ppm) was reapplied 31 May and 13 June as described above. Soil drenches of 5, 10, or 20 ppm paclobutrazol were additional treatments. Two nonPGR-treated controls were included: pruned at 0 WAT, and pruned at 0 and 4 WAT. There were eight replications per treatment placed in a randomized complete block design on a container bed under full sun and drip irrigation. At 6, 9, and 12 WAT, growth, flowering, growth habit, number of structural branches (>15 cm long), and level of bacterial spot infection by Pseudomonas andropogonis were recorded. Marketability was recorded 12 WAT and phytotoxicity noted 1, 4, 5, 6, 9, and 12 WAT. No PGR treatment effectively suppressed growth, or enhanced quality or marketability of `Barbara Karst' bougainvillea grown in 3.8-L containers. Furthermore, daminozide reduced the number of structural branches and maleic hydrazide was phytotoxic.
