Malays. Appl. Biol. (1997) 26(1): 63-73
TRUNCATION SELECTION OF ORTETS FOR CLONAL EVALUATION IN COCOA
SHAHARUDIN SAAMIN
Strategic, Environment and Natural Resources Research Centre, MARDI, P.O. Box 12301, 50774 Kuala Lumpur, Malaysia
ABSTRACT
Heterosis in cocoa (Theobroma cacao L) has been exploited to produce progenies and clones for planting materials Current emphasis in cocoa breeding is on selection of superior individuals (ortets or mother trees) for clonal evaluation Ortets form the basis for clones. Thus, it is very important to follow an effective selection procedure. Examination ol cumulative pod yield data from 6 progeny trials and 6 family row observations involving 9,591 trees indicated that the trial mean plus half to one standard deviation could be used as selection cut-off point for each trial or family row observation. This gave a selection intensity of approximately 15% to 25%. Further selection pressure on bean weight, shape and number resulted in less potential ortets that could be evaluated as clones. Early high yielding trees maintained their yield trend in later years. This means that early selection of ortets could be done effectively. Selected ortets were vegetatively propagated for entry into a preliminary clonal trial.
ABSTRAK
Kejadian heterosis pada tanaman koko (Theobroma cacao L) telah dieksploit untuk memperolehi progeni dan klon sebagai bahan tanaman. Penekanan program membaikbaka koko ialah untuk mendapatkan pokok-pokok induk berpotensi untuk dibiak dan dikaji sebagai klon. Dengan itu proses pemilihan pokok induk yang berpotensi eloklah dijalankan dengan berkesan. Penelitian data jumlah buah (kumulatif) daripada 6 percubaan dan 6 pemerhatian progeni meliputi 9,591 pokok menunjukkan pokok-pokok yang mengeluarkan hasil 1/2 hingga 1 sisihan piawai lebih tinggi dari purata berpotensi dipilih sebagai pokok induk. Cara ini menentukan keamatan pemilihan setinggi 15% hingga 25%. Tekanan pilihan ke atas ciri-ciri seperti berat, bentuk dan bilangan biji akan meninggikan lagi keamatan pemilihan. Pokok-pokok yang mengeluarkan buah yang banyak pada peringkat awal terus mengekalkan daya penghasilan sebegitu. Ini bermakna pemilihan untuk mendapatkan pokok induk boleh dijalankan lebih awal dengan efektif. Pokok-pokok induk yang terpilih dibiakkan dan jimasukkan dalam pengujian klon.
Key words: Clones, cocoa, ortets, selection
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