SUMMARY
Benih ikan mas telah mengalami penurunan kualitas genetik yang menyebabkan penurunan performa fenotipik di lingkungan budidaya. Salah satu upaya perbaikan genetik adalah melalui pembentukan populasi sintetis yang merupakan penggabungan potensi genetik beberapa populasi plasma nutfah ikan mas. Penelitian ini bertujuan membentuk dan mengevaluasi performa genotipik dan fenotipik populasi sintetis ikan mas, yang merupakan penggabungan dari strain Rajadanu, Majalaya, Sutisna, Wildan, dan Sinyonya. Performa genotipik dievaluasi menggunakan metode mikrosatelit DNA, sedangkan performa fenotipik dievaluasi menggunakan analisis biometrik terkait kegiatan budidaya. Hasil penelitian menunjukkan bahwa nilai keragaman genetik populasi sintetis lebih tinggi 55,0%-287,5% dengan tingkat inbreeding 40,0%-77,14% lebih rendah dibanding populasi-populasi pembentuknya. Hal ini berdampak terhadap performa fenotipik populasi sintetis yang lebih baik, diindikasikan dengan peningkatan panjang, bobot akhir, dan tingkat produktivitas, masing-masing sebesar 2,5%-20,6%; 9,4%-61,8%; dan 18,2%-66,0% lebih baik dibanding populasi-populasi pembentuknya. Peningkatan kualitas genetik dan performa fenotipik populasi sintetis ini memberikan peluang untuk memperbaiki kualitas benih ikan mas pada kegiatan budidaya.Common carp in Indonesia has experienced a decline in genetic quality. The progressive decline leads to a significant decrease in carp performance in the farming environment. One of the efforts to genetically improve carp growth performance is through developing synthetic carp populations, which is a blend of the genetic potentials from several germplasm populations. This study aimed to form and evaluate the performance of genotypic and phenotypic of synthetic populations of common carp, blended from five strains of common carp, i.e., Rajadanu, Majalaya, Sutisna, Wildan, and Sinyonya. The genotypic performance was evaluated using the DNA microsatellite method. The phenotypic performance was assessed using biometric analysis, especially in terms of culture performance. The results showed that the genotypic performance of the synthetic populations of common carp was better than that of the founder strains. This performance was indicated by higher genetic diversity values, about 55.0%-287.5% and lower levels of inbreeding, about 40.0%-77.1%, compared with their founder populations. Phenotypic performance of the synthetic populations is also better than their founder populations, indicated by higher body length, weight, and productivity, about 2.5%-20.6%, 9.4%-61.8%, and 18.2%-66.0%, respectively. The improvement on genetic quality and phenotypic performance of the synthetic population provide opportunities to improve the quality of common carp fry in aquaculture activity.