Abstract:
Sri Lanka is a country with an outstanding biodiversity including a rich native flora. Some of these
native plants have the potential to be introduced to the landscape industry as ornamental plants with
minor improvements. Crotalaria retusa L. is one such plant with beautiful yellow colour flowers
which attract butterflies in large numbers. However, architecture of the plant, mainly natural plant
height narrows its suitability to be introduced as a potted ornamental plant. Paclobutrazol (PBZ),
an efficient plant growth retardant which inhibits synthesis of sterols and gibberellins in plants
resulting a reduced internodal growth, could be used successfully to develop dwarf plants. Hence,
the objective of the present study was to identify the best PBZ level to produce dwarf potted plants
and to determine the customer satisfaction for overall appearance of the treated plants. Four PBZ
levels (3, 4, 5 and 6 mg/100 ml) were applied as a soil drench to seedlings. Control plants were
treated similarly with distilled water. Complete Randomized Design (CRD) was used with 12 plant
replicates. All plants treated with PBZ showed a reduced height compared to the control plants.
Plant height and flower size were reduced with increasing PBZ concentrations. Significantly shorter
internodal distances and heights were recorded in plants treated with 6 mg /100 ml PBZ. The highest
dwarfness was observed in plants treated with 6 mg /100 ml PBZ but with no flowers. According
to the customer satisfaction survey the customers were not satisfied with plants treated with the
highest PBZ level as there were no colourful flowers and the plants were extremely dwarf. Highest
preference was received from the customers for plants treated with 4 mg/100 ml PBZ level.
Therefore, the present study confirmed that 4 mg/100 ml PBZ as the best level to develop dwarf
ornamental potted plants of C. retusa.
