<p><strong>(<em>The Effect of Explant Types and Amino Acids on Embryogenic Callus Initiation and Proliferation of Phalaenopsis Var. ‘Raiza Agrihorti’</em>)</strong></p><p>Penyiapan kalus embriogenik (KE) yang optimal memiliki peranan penting dalam menghasilkan benih bermutu Phalaenopsis skala komersial. Kendala utama yang dihadapi ialah inisiasi dan proliferasi KE yang masih rendah, serta akumulasi fenolik yang tinggi. Penelitian dilakukan di Laboratorium Kultur Jaringan Balithi dari Agustus 2019 hingga Juli 2020. Penelitian menggunakan Rancangan Acak Kelompok (RAK) pola split plot dan faktorial dengan lima ulangan. Percobaan-1: jenis eksplan (pucuk, pangkal, dan daun plantlet) sebagai petak utama dan perlakuan asam amino (tanpa asam amino, L-Proline, L-Glutamine, L-Cysteine, dan Casein-Hydrolisate) dengan konsentrasi 150 mg/l pada medium PC1 (1/2 MS + 1,0 mg/l TDZ + 0,5 mg/l BAP + 20 g/l sukrosa) sebagai anak petak. Percobaan-2: faktor-1 ialah jenis asam amino (L-Proline, L-Cysteine; L-Glutamine, dan Casein-Hydrolisate) dan faktor-2 ialah konsentrasi asam amino (0, 75, 150, 225, dan 300 mg/l). Hasil penelitian menunjukkan bahwa inisiasi KE Phalaenopsis var. ‘Raiza Agrihorti’ terbaik didapatkan dari pangkal plantlet dan 150 mg/l L-Glutamine dengan waktu inisiasi 18,3-24,0 hari, 80-100% pembentukan KE, dan ukuran KE 0,4-0,5 cm3. Proliferasi KE terbaik ditemukan pada L-Glutamine dengan konsentrasi 150 mg/l. Proliferasi KE mencapai 100% dengan penambahan berat segar sebesar 0,39 g, tingkat multiplikasi (MR) 4,55 kali dan pencokelatan 4,0%. Hasil penelitian ini berpotensi tinggi untuk diterapkan pada kultur starter Phalaenopsis hibrida lain.</p><p><strong>Keywords</strong></p><p>Phalaenopsis hibrid; Asam amino; Inisiasi; Kalus embriogenik; Proliferasi</p><p><strong>Abstract</strong></p><p>Setup of the optimum Phalaenopsis embryogenic callus (EC) is an important role in producing qualified-seedlings of Phalaenopsis in commercial scale. The main constraints that are still being faced are the low rate of culture proliferation and high phenolic accumulations. The research was carried out at the Tissue Culture Laboratory-Indonesian Ornamental Plants Research Institite, from August 2019 through July 2020. The split plot and factorial designs were arranged using a Randomized Completely Block Design (RCBD) with five replications. Experiment-1: explants type (shoot tip, basal part, and leaf of plantlet) was used as main plot and amino acids (amino acids free, L-Proline, L-Glutamine, L-Cysteine, and Casein-Hydrolisate) with 150 mg/l concentration on medium PC1 (1/2 MS + 1,0 mg/l TDZ + 0,5 mg/l BAP + 20 g/l sukrosa) as subplot. Experiment-2: the first factor was amino acids type (L-Proline, L-Cysteine; L-Glutamine, and Casein-Hydrolisate) and the second factor was amino acids concentration (0, 75, 150, 225, and 300 mg/l). Results of the studies revealed that the best EC initiation of Phalaenopsis var. ‘Raiza Agrihorti’ was produced by basal part of plantlet and PC1 medium containing 150 mg/l L-Glutamine with EC Initiation time was 18.3-24.0 days, 80-100% of EC formation and size of 0.4-0.5 cm3. The best proliferation of EC was found in L-Glutamine with 150 mg/l concentration. EC proliferation reached 100% with 4.55 EC multiplication rate, 0.39 g EC fresh weight added, and EC browning as low as 4.0%. The established method is high possibly applied for other Phalaenopsis hybrids.</p>