The Use of Paclobutrazol as a Growth Retardant for Storing
Indigenous Forest Seedlings

by

Aznina Aminor
B. For. Sc.
1996

Supervisor: Assoc. Prof. Dr. Sheikh Ali Abod
Co-supervisor: Dr. Jamaluddin Basharuddin

Artificial regeneration of dipterocarp forests involves a broad spectrum of limitations. One of the main problems is to get a regular supply of planting stocks. Storage of germinated seedlings inhibited with growth retardant may be the solution to a regular supply of planting material for plantation programs. Two species of dipterocarp seedlings, Meranti Tembaga (Shorea leprosula) and Meranti Sarang Punai (Shorea parvifolia) were used in this study. Each species with two sizes were subjected to a Paclobutrazol growth retardant (PP333) at concentrations of 0, 0.1, 0.25, 0.5, 1.0, 2.0, 4.0, 8.0 and 12.0 g/l. Plants were foliar sprayed to run-off so that excess chemical was also deposited into the potting soil. Plants were measured for height, diameter, leaf area, number of branches, number of leaf and stomatal conductance. They were harvested after 12 weeks for root and shoot dry weight measurements. Paclobutrazol significantly reduced the growth of Shorea leprosula and Shorea parvifolia for both sizes. The effects of chemical increased with increasing chemical concentration from 0.25 g/l to maximum 12.0 g/l. Weekly measurements of height, leaf area increments and stomatal conductance revealed the differences in values between treated plants and control generally increased with time. However, this is a preliminary study on dipterocarp species and further research is needed before being recommended for practical application.

Citation:
Aznina, A. 1996. The use of Paclobutrazol as a growth retardant for storing indigenous forest seedlings. B. For. Sc. Project Report. Faculty of Forestry, Universiti Pertanian Malaysia. 63 leaves. (http://www.oocities.org/EnchantedForest/Palace/1170/abnina.html)