Naskah diterima tanggal 5 September 2014 dan disetujui untuk diterbitkan tanggal 22 Desember 2014 ABSTRAK.Teknik pengairan memengaruhi pertumbuhan, hasil buah, dan kualitas buah jeruk Siompu. Salah satu teknik pengairan yang prospektif diteliti untuk meningkatkan kualitas hasil Jeruk Siompu adalah pengairan separuh daerah akar. Penelitian bertujuan untuk mengetahui pengaruh pengairan separuh daerah akar terhadap pertumbuhan daun dan kualitas buah jeruk Siompu. Penelitian ini menggunakan rancangan acak kelompok dengan tiga ulangan. Penelitian ini terdiri atas lima perlakuan pengairan yaitu (P0) pengairan seluruh daerah akar (PDA) 20 l air/pohon, (P1) pengairan separuh daerah akar (PSDA) 20 l air/pohon, (P2) PSDA 15 l air/ pohon, (P3) PSDA 10 l air/pohon, dan (P4) PSDA 5 l air/pohon. Teknik PSDA yaitu air diberikan hanya pada sebagian daerah akar (satu sisi) tanaman, sedangkan sebagian daerah akar (sisi lainnya) tidak diberikan air atau diberi peluang mengalami kondisi kering, masing-masing dengan interval waktu 8 hari. Hasil penelitian menunjukkan bahwa PSDA meningkatkan kandungan asam absisat (ABA) daun dan mempertahankan pertumbuhan daun, ukuran buah, sari buah, dan brix seperti perlakuan PDA, tetapi tidak dapat meningkatkan kualitas buah dan mengurangi kadar K daun. Pada musim kemarau, teknik PSDA 10 l air/pohon atau penghematan air 50% dibanding kontrol dapat direkomendasikan untuk pengairan tanaman jeruk Siompu, meskipun perlu dilakukan studi integrasi pengairan separuh daerah akar dengan pemupukan dan mulsa pada musim kemarau.Katakunci: ABA; Jeruk Siompu; Kualitas buah; Pertumbuhan; Pengairan separuh daerah akar ABSTRACT. Irrigation method may affects the growth, fruit yield, and its quality of Siompu citrus. One of the promising irrigation method to be tested on Siompu citrus is partial root zone irrigation (PRZI). The aim of research is to determine the effect of PRZI on leaf growth and yield quality of Siompu citrus. The experiment was designed as a randomized complete block design with three replications. The experiment consisting of five treatments namely (P0) the whole root zone irrigation (FRI) was irrigated with 20 l water plant, (P1) the PRZI was irrigated with 20 l water/plant, (P2) the PRZI was irrigated with 15 l water/plant, (P3) the PRZI was irrigated with 10 l water/plant, (P4) the PRZI was irrigated with 5 l water/plant, PRZI treatments were done by watering one root zone side while the other side was allowed to dry and irrigation was shifted to the dry side while the wet side was allowed to dry every 8 days irrigation interval, respectively. The results showed that the PRZI treatment increased leaf ABA content and maintained leaf growth, fruit size, juice, and brix at the level of the FRI treatment, however, PRZI was not increase fruit quality and also decreased leaf K content. PRZI 10 l water/plant can be recommended to irrigate Siompu citrus during dry season, however, study on the integration of PRZI with fertilizer and mulch during dry season are needed to be done.