Keragaman Buah Jeruk Keprok SoE Mutan Generasi M 1 V 2 Hasil Induksi Mutasi Sinar Gamma (Fruit Diversity of SoE Mandarin Mutant at M 1 V 2 Generation Resulted from Gamma Irradiation) Hidayatul Arisah* dan Baiq Dina Mariana Balai Penelitian Tanaman Jeruk dan Buah Subtropika. Jl. Raya Tlekung No. 1 Junrejo, Batu Jawa Timur 65301, Indonesia Telp. (0341) 592683; Faks. (0341) 593047 *E-mail: hidayatularisah@gmail.com Diajukan: 18 Mei 2017; Direvisi: 20 Juli 2017; Diterima: 29 September 2017 ABSTRACT Mutation induced by gamma rays can occur in any random site at allelic level causing genetic variation in every individual plants in a population. Induced mutation on the local citrus varieties SoE allows the increase of diversity in both qualitative and quantitative traits. The study was aimed to determine the influence of mutation on diversity of fruit characters of SoE mandarin mutant. The experiment was conducted in Experimental Field and Plant Breeding Laboratory of Indonesian Citrus and Subtropical Fruits Research Institute in 2014. Descriptive observations based on IPGRI descriptor list for citrus were made on fruit weight, fruit length, fruit diameter, skin thickness, seed number, segment number, skin color, juice volume, juice color, and taste. The result showed that the effect of mutation on diversity of qualitative characters was relatively low; mutant characters were almost identical to those of the control parent. In contrast, quantitative characters showed more diverse result in which genetic similarity percentage ranged from 5.06–33.89%. The highest diversity value was observed on seed number and the lowest one was observed on segment number. There were seven accessions showing seedless character of which 90% of their fruits were seedless with ≤5 seeds/fruit. The induced mutation resulted in fewer seed number and thinner peel of mutant’s fruits than those of citrus fruits of SoE. Based on cluster analysis, selected mutant accessions had low diversity and 76.40% genetic similarity. Keywords: citrus (Citrus reticulata), gamma radiation, morphology character. ABSTRAK Mutasi sinar gamma dapat terjadi secara acak pada level alelik yang menghasilkan keragaman genetik baru. Mutasi pada jeruk menginduksi keragaman karakter secara kuantitatif maupun kualitatif. Tujuan penelitian ini ialah mengetahui pengaruh mutasi terhadap peningkatan keragaman karakter buah pada mutan tanaman jeruk lokal SoE. Penelitian dilaksanakan di Kebun Percobaan dan Laboratorium Pemuliaan Tanaman Balai Penelitian Tanaman Jeruk dan Buah Subtropika Jawa Timur, tahun 2014. Pengamatan dilakukan secara deskriptif berdasarkan Internasional Plant Genetic Resources Institute (IPGRI), pada karakter bobot buah, tinggi buah, diameter buah, ketebalan kulit, jumlah biji, jumlah juring, volume jus, warna kulit buah, warna jus, dan rasa. Hasil penelitian menunjukkan bahwa pengaruh mutasi pada peningkatan keragaman karakter kualitatif relatif rendah; mutan hampir mirip dengan tanaman kontrol untuk karakter kualitatif. Perbedaan pada karakter kuantitatif, ditunjukkan dengan nilai koefisien keragaman 5,06–33,89%, nilai tertinggi pada karakter jumlah biji, sedangkan karakter jumlah juring memiliki nilai terendah. Terdapat tujuh aksesi yang yang menghasilkan buah dengan persentase buah seedless (jumlah biji ≤5) mencapai 90%. Mutasi induksi menyebabkan berkurangnya jumlah biji dan menurunnya ukuran ketebalan kulit buah dibanding dengan kontrol SoE. Berdasarkan analisis klaster, aksesi-aksesi mutan terseleksi mempunyai tingkat keragaman kecil dengan level kemiripan 76,40%. Kata kunci: jeruk keprok (Citrus reticulata), radiasi sinar gamma, karakter morfologi. Hak Cipta © 2017, BB Biogen Bul. Plasma Nutfah 23(2):69–80