GROWTH OF SEVERAL RUBBER CLONES FOR TIMBER PRODUCTION

The study was aimed at evaluating the growth behaviour of selected existing rubber clones under forest plantation management to produce timber. The clones were initially developed under intensive agricultural system to produce latex. We observed growth performance of seven-year-old rubber plantations at Bukit Hari Forest Reserve and Sungai Buloh Forest Reserve, Selangor. In both sites clone PB 235 had the greatest height and diameter. All clones performed better under lower density (600 trees/ha) plantation compared with the higher density (900 trees/ha). Effect of clones was significant in individual as well as in the combined analyses. Interaction between clone and site was highly significant but all clones maintained the same ranking across sites. Clone by density interaction was not significant and coefficients of variation of clonal materials were lower than clonal seedlings. Kajian ini bertujuan menilai pertumbuhan beberapa klon pokok getah yang dipilih untuk pengurusan ladang hutan bagi penghasilan balak. Klon pada mulanya dibangunkan di bawah sistem pertanian intensif bagi penghasilan lateks. Kami memerhati pertumbuhan ladang getah berusia tujuh tahun di Hutan Simpan Bukit Hari dan Hutan Simpan Sungai Buloh, Selangor. Di kedua-dua tapak, klon PB 235 menunjukkan ketinggian dan diameter yang terbesar. Semua klon menunjukkan pertumbuhan yang lebih baik apabila ditanam pada ketumpatan rendah (600 pokok/ha) berbanding ketumpatan tinggi (900 pokok/ha). Analisis tapak individu dan analisis tergabung menunjukkan kesan klon yang signifikan. Interaksi antara klon dan tapak adalah sangat signifikan namun semua klon menunjukkan kedudukan yang sama di kedua-dua tapak. Interaksi klon dan ketumpatan adalah tidak signifikan dan pekali ubahan bahan klon adalah lebih rendah daripada anak benih klon.