Sains Malaysiana 41(10)(2012): 1187–1192

Morphological and Physiological Response of Syzygium

myrtifolium (Roxb.) Walp. to Paclobutrazol

(Respons Morfologi dan Fisiologi Syzygium myrtifolium (Roxb.) Walp. Terhadap Paclobutrazol)

Ahmad Nazarudin Mohd Roseli*

Forest Research Institute Malaysia (FRIM), 52109 Kepong, Selangor, Malaysia

Tsan Fui Ying

Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor, Malaysia

Mohd Fauzi Ramlan

Universiti Putra Malaysia (UPM), 43400 Serdang, Selangor, Malaysia

Received:  1 March 2012 / Accepted:  20 June 2012

ABSTRACT

Syzygium myrtifolium (Roxb.) Walp. is a popular landscape plant in Malaysia. This species is always planted as hedge plant and topiary. However, it requires frequent trimming to maintain its form and aesthetic functions as it grows vigorously. Conventional trimming technique by using trimming shear or trimming machine is currently practiced in landscape maintenance which is time consuming, labour intensive and costly. Therefore, a study was conducted to investigate the effects of a plant growth retardant, paclobutrazol, on the growth and physiological response of S. myrtifolium. The plants were planted in polyethylene bags sized 33 cm in height × 27 cm in diameter and filled with soil, organic matter and sand (3:2:1). Paclobutrazol at rates of 0, 1.25, 2.50 and 3.75 g L-1 were soil drenched at 30 days after the plants were trimmed and new shoots were produced. Paclobutrazol significantly reduced plant height and leaf area but increased the leaf area index. Reduced photosynthetic rates were recorded with the treated plants as compared to the control plants. In addition, paclobutrazol at 3.75 g L-1 significantly reduced the transpiration rate as compared with the control plants and plants treated with 1.25 g L-1 of paclobutrazol. However, stomatal conductance was not affected significantly by paclobutrazol. The growth inhibition effect of paclobutrazol reduced the trimming activity in S. myrtifolium. Chlorophyll fluorescence measurement indicated that physiological processes in the paclobutrazol-treated plants were not affected. Paclobutrazol is concluded to offer a better approach in maintaining the growth of S. myrtifolium.

Keywords: Chlorophyll fluorescence; growth inhibition; landscape maintenance; plant growth retardant

ABSTRAK

Syzygium myrtifolium (Roxb.) Walp. merupakan sejenis pokok landskap yang popular di Malaysia. Pokok ini sering ditanam sebagai pokok pagaran dan topiari. Walau bagaimanapun, pokok ini perlu kerap dipangkas kerana pertumbuhannya yang cepat. Teknik pemangkasan menggunakan gunting atau mesin pemangkas biasa diamalkan dan memerlukan jangka masa yang lama, tenaga kerja yang banyak serta kos yang tinggi. Oleh itu, satu kajian telah dijalankan bagi mengenal pasti kesan perencat pertumbuhan pokok, paklobutrazol terhadap pertumbuhan dan respon fisiologi pokok S. myrtifolium. Pokok ditanam di dalam beg politena yang berukuran 33 cm tinggi dan bergaris pusat 27 cm serta diisikan dengan campuran tanah, bahan organik dan pasir (3:2:1). Paklobutrazol dengan kadar 0, 1.25, 2.50 dan 3.75 g L-1 disiram ke media penanaman selepas 30 hari pokok-pokok itu dipangkas dan mengeluarkan daun-daun yang baru. Paklobutrazol didapati mengurangkan tinggi pokok dan keluasan daun, tetapi meningkatkan indeks luas daun berbanding pokok kawalan. Kadar fotosintesis yang rendah juga direkodkan bagi pokok yang dirawat dengan paklobutrazol. Paklobutrazol dengan kadar 3.75 g L-1 menurunkan kadar transpirasi berbanding pokok yang dirawat dengan kadar 1.25 g L-1 paklobutrazol dan juga pokok kawalan. Walau bagaimanapun, konduksi stomata tidak terjejas oleh paklobutrazol. Kesan perencatan pertumbuhan pokok oleh paklobutrazol ini dapat mengurangkan aktiviti pemangkasan bagi spesies S. myrtifolium. Pengukuran terhadap floresen klorofil menunjukkan proses fisiologi pokok yang dirawat dengan paklobutrazol tidak terjejas. Paklobutrazol merupakan satu pendekatan yang sesuai dalam menyelenggara pertumbuhan pokok S. myrtifolium.

Kata kunci: Floresen klorofil; penyelenggaraan landskap; perencatan pertumbuhan; perencat pertumbuhan pokok perencat

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*Corresponding author; email: nazarudin@frim.gov.my