Front & back matter

Growth, precocity and productivity of starfruit (Averrhoa carambola L.) in response to root restrictive membranes (Kesan membran pembatasan akar terhadap tumbesaran, kematangan dan daya pengeluaran belimbing besi (Averrhoa carambola L.) M. Zainudin* Key words: growth, precocity, productivity, root restrictive membrane, starfruit Abstrak Tumbesaran serta peningkatan hasil pokok buah-buahan saka dapat dikawal melalui banyak kaedah. Pembatasan akar menggunakan membran geotekstil telah dikaji terhadap belimbing besi bagi mengawal tumbesaran tampang dan meningkatkan hasil. Sebanyak 60 pokok belimbing (B10 dan B17) yang berumur satu tahun telah diujikaji dengan empat perlakuan pembatasan akar menggunakan reka bentuk blok lengkap terawak yang diulangsama sebanyak enam kali. Ketinggian pokok dan garis pusat batang tanaman yang dibataskan akarnya berkurangan sebanyak 10-12% berbanding dengan kawalan. Tumbesaran pucuk seperti jumlah keluasan daun, bilangan daun dan bilangan pucuk juga berkurangan. Pembungaan pula lebih cepat manakala purata berat buah, bilangan buah dan hasil yang boleh dipasarkan tidak terjejas. Tambahan pula, hasil tanaman daripada kaedah pembatasan akar adalah lebih tinggi daripada hasil tanaman yang ditanam secara konvensional pada tahun kedua pengeluaran. Pembatasan akar juga dapat mengurangkan tumbesaran tampang dan mempercepat pengeluaran hasil. Kaedah ini boleh digunakan secara praktik untuk mengawal saiz pokok serta dapat menjimatkan penggunaan tenaga buruh dalam perusahaan penanaman belimbing. Abstract Tree vigour control and yield improvement of perennial fruit trees could be achieved through many cultural practices. A study was conducted on starfruit trees using geotextile membrane to examine the effects of root restriction in controlling vegetative growth and improving precocity. Sixty one-year-old starfruit trees (B10 and B17) were subjected to four treatments of root restrictive membranes arranged in a randomized complete block design with six replications. Plant height and stem diameter of root restrictive-membraned plants were reduced by 10-12% compared to the control. Vegetative shoot vigour also decreased as indicated in the reduction of total leaf area, leaf number and shoot number. Although flowering was enhanced, average fruit weight, fruit number and marketable yield were unaffected. Moreover, the yield of restricted plants was more compared to the yield obtained through conventional planting in the second year of production. This study shows that root restrictive membrane is an effective mean to reduce vegetative growth and promote precocity. It offers a practical approach to control tree size and labour saving in commercial planting of starfruits