Master of Science (MS)


Plant, Environmental Management and Soil Sciences

Document Type



The effect of growth regulators gibberellic acid (Pro-Gibb™), daminozide (B-Nine™), ancymidol (A-Rest™) and paclobutrazol (Bonzi™) were evaluated on species of Clerodendrum grown as flowering pot plants. Studies on photoperiod and post-production longevity were also included. Experiments were conducted on C. bungei, C. thomsoniae, C. ugandense, C. phillippinum, C. paniculata and C. speciosissimum in polycarbonate greenhouses. For C. thomsoniae the best growth control was achieved by applying paclobutrazol and ancymidol drench at a rate of 1.0 mg a.i. /pot. For C. ugandense, the most appropriate application rate of PGR was paclobutrazol drench at 5 to 15 mg a.i./pot. C. bungei did not respond significantly to either daminozide or paclobutrazol treatments compared to control. Based on the visual quality rating, C. bungei were acceptable as marketable plants until day 7, and C. ugandense were acceptable as marketable plants until day 5. Neither daminozide nor paclobutrazol had any effect on C. bungei quality ratings in post-production. In C. ugandense, however, there were significant differences in post-production when comparing the daminozide and the paclobutrazol treatments. On day 5, 7 and 11, the paclobutrazol treated plants had significantly lower quality ratings compared to control and compared to those treated with daminozide. It appears that the paclobutrazol treatment may produce a quality plant, but has a negative effect on post-production longevity. Gibberellic acid at 10 ppm was considered the best rate and most economical rate for promoting optimum vegetative growth of C. thomsoniae to sufficiently cover a round support hoop. C. speciosissimum, C. phillippinum, C. paniculata and C. speciosissimum were determined to be long day plants (12-h photoperiod or longer). Height of C. paniculata and C. speciosissimum was significantly increased by the 12 or 16-h photoperiod.



Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Jeff S. Kuehny