Paclobutrazol effects on growth performance and public preference on potted Syzygium myrtifolium (Roxb.) Walp.

A study was conducted to investigate the effects of plant growth retardant, Paclobutrazol (PBZ) on the growth performance and public preference on the treated-Syzygium myrtifolium (Roxb.) Walp. for container planting. In landscape, S. myrtifolium is always planted as a hedge plant, single planting or topiary for roadsides, urban parks, house lawns and golf clubs. However, it requires frequent trimming to maintain the aesthetic functions as it grows vigorously. PBZ was thought to be a better technique to reduce trimming activity and at the same time able to maintain crown form. S. myrtifolium plants were planted in polyethylene bags (33 cm x 27 cm) filled with soil, organic matter and sand (3:2:1). PBZ at rates of 0, 1.25, 2.50 and 3.75 g/L were soil drenched at 30 days after the plants were trimmed at approximately 100 cm in height and new shoots were produced. Growth performance (plant height, leaf area and leaf area index) of S. myrtifolium wereobserved monthly, while public preference on the appearance, aesthetic value and willingness to purchase S. myrtifolium were obtained by using a questionnaire form.Fifty individuals of various occupations related to the landscape industry were randomly chosen from 140 participants of a series of landscape courses conductedby the Forest Research Institute Malaysia (FRIM) over a period of five years. PBZ significantly reduced plant height and leaf area, however the leaf area index increased. No significant difference in terms of growth performance of S. myrtifolium was observed among different rates of PBZ. Enhanced appearance and aesthetic value of S. myrtifolium were also indicated by the respondents. Application of PBZ greatly increased the market value of S. myrtifolium for container planting purposes.