ABSTRACTBanana and plantain are important for food security. Increase of genetic variability is difficult because most of edible bananas are triploid, sterile and parthenocarpy. Therefore, breeding through convetional method are difficult. The objective of this research were to evaluate phenotypic variation of banana cv. Ampyang (Musa acuminata, AAA, subgroup non-Cavendish) regenerated from in vitro induced mutation by gamma irradiation in a greenhouse. The objectives of this research were to characterize and evaluate phenotypic diversity of banana cv. Ampyang plant, in vi tro regenerated from gamma irradiated plantlet in a greenhouse. The phenotypes (both quantitative and qualitative characters) were evaluated when the plants were at six months after acclimatization. Result indicated banana plant sregenerated from gamma irradiated explants exhibited lower plant height, shorter leaf, and leaf length by leaf width ratio than from non-irradiated ones. Population of banana cv. Ampyang gamma irradiated at30, 40, 45 and 50 Gy showed broader variation in qualitative characters than those treated with 0 Gy. Banana cv. Ampyang originated from explants treated with 0 Gy showed similar stomatal density than those from explants treated with 45 and 50 Gy. On the other hand, those originated from explants treated with 20, 25, 30 or 40 Gy showed lower stomatal densities than those treated with 0 Gy. The results have demonstrated that mutation breeding with in vitro technique could produce morphological changes as well as increase in variability of quantitative traits. A number of these parameters were supposed to be applicable for characterization of variation in other banana cultivars.Key words: Musa acuminata (AAA), stomata density, doses of gamma irradiationABSTRAKPisang penting untuk keamanan pangan. Peningkatan keragaman genetik pada pisang sulit dilakukan karena sebagian besar pisang yang dapat dimakan bersifat triploid, steril dan partenokarpi.Oleh sebab itu, pemuliaan tanaman secara konvensional sulit dilakukan. Tujuan penelitian ini ialah untuk mengevaluasi variasi fenotipik pisang cv. Ampyang (Musa acuminata, AAA, subgroup non-Cavendish)yang diregenerasikan dari kultur in vitro dan diinduksi mutasi dengan sinar gamma. Fenotipe (karakter kualitatif dan kuantitatif) dievaluasi ketika tanaman berumur 6 bulan setelah aklimatisasi. Hasil penelitian menunjukkan bahwa tanaman pisang yang diregenerasikan dari eksplan yang diiradiasi sinar gamma memiliki tinggi tanaman yang lebih rendah, daun yang lebih pendek, dan rasio panjang dan lebar daun yang lebih rendah dibanding tanaman non-iradiasi. Populasi pisang cv. Ampyang hasil iradiasi sinar gamma 30, 40, 45 dan 50 Gy menunjukkan variasi yang lebih lebar dalam karakter kualitatif dibanding tanaman kontrol (0 Gy). Pisang cv. Ampyang asal eksplan kontrol (0 Gy) menunjukkan densitas stomata yang sama dengan tanaman eksplan yang diiradiasi sinar gamma 45 dan 50 Gy. Tanaman yang berasal dari eksplan yang diiradiasi sinar gamma 20, 25, 30 or 40 Gy menunjukkan densitas stomata yang lebih rendah dari tanaman kontrol (0 Gy). Hasil penelitian ini menunjukkan bahwa pemuliaan mutasi dengan teknik in vitro dapat menghasilkan perubahan morfologi dan juga peningkatan variabilitas sifat kuantitatif dan sejumlah parameter tersebut diharapkan dapat diaplikasikan untuk karakterisasi variasi kultivar pisang lainnya.Kata kunci : Musa acuminata (AAA), densitas stomata, dosis iradiasi sinar gamm