Ketahanan Galur Isogenik IRBBN dan Galur Harapan Padi terhadap Patotipe Xanthomonas oryzae pv. oryzae Dominan pada Tanaman Padi di Indonesia

The resistance genes in IRBB near isogenic lines (NILs) which was introduced from International Rice Research Institute (IRRI) have been known. It could be used as source of resistance to the dominant Xanthomonas oryzae pv. oryzae (Xoo) pathotype in Indonesia. The purpose of this research was to evaluate IRBBN NILs and promising lines to the dominant Xoo pathotype in Indonesia i.e. pathotype III, IV, and VIII. Research was conducted at Sukamandi exprerimental field station in Subang, West Java, at dry seasons (DS) 2012 and wet seasons (WS) 2012/2013. The experiment was conducted following Factorial Randomized Completely Block Design with three replications. The first factor were three pathotype Xoo that was pathotype III, IV, and VIII, while the second factor were 20 IRBB lines, 6 promising lines, and 6 refferer varieties such as Conde, Lusi, Logawa, Java 14, Angke, dan Inpari 1. The result showed that three isogenic lines i.e. IRBB 21, IRBB 50, and IRBB 52 were resistant to Xoo pathotype III, IV, and VIII at DS 2012. At WS 2012/2013 was obtained five isogenic lines i.e. IRBB 52, IRBB 53, IRBB 54, IRBB 56, and IRBB 57 resistant to Xoo pathotype III, IV, and VIII. IRBB 52 was consistently resistant to the three Xoo pathotypes in two cropping seasons. It could be recommended to be used as donor in developing new resistant varieties to bacterial leaf blight.   Abstrak Galur isogenik IRBB introduksi dari International Rice Research Institute (IRRI) telah diketahui gen ketahanannya dan dapat digunakan sebagai sumber ketahanan terhadap patotipe Xanthomonas oryzae pv. oryzae (Xoo) dominan di Indonesia. Kegiatan penelitian ini bertujuan untuk mengevaluasi ketahanan galur isogenik dan galur harapan terhadap patotipe Xoo dominan di Indonesia, yaitu patotipe III, IV, dan VIII. Penelitian dilaksanakan di Kebun Percobaan Sukamandi, Subang, Jawa Barat pada musim kemarau (MK) 2012 dan musim hujan (MH) 2012/2013. Penelitian dilakukan dengan Rancangan Faktorial Acak Kelompok dengan tiga ulangan. Faktor pertama adalah tiga patotipe Xoo, yaitu patotipe III, IV, dan VIII, sedangkan faktor kedua yaitu materi yang diuji sebanyak 20 galur IRBB, 6 galur harapan padi, dan 6 varietas pembanding, yaitu Conde, Lusi, Logawa, Java 14, Angke, dan Inpari 1. Hasil penelitian menunjukkan bahwa galur isogenik IRBB 21, IRBB 50, dan IRBB 52 bereaksi tahan terhadap Xoo patotipe III, IV, dan VIII pada MK 2012. Pada MH 2012/2013 diperoleh lima galur isogenik IRBB 52, IRBB 53, IRBB 54, IRBB 56, dan IRBB 57 bereaksi tahan terhadap Xoo patotipe III, IV, dan VIII. Galur isogenik IRBB 52 konsisten tahan terhadap Xoo patotipe III, IV, dan VIII pada dua musim tanam. Oleh karena itu, galur tersebut dapat direkomendasikan untuk dijadikan tetua tahan untuk perakitan varietas tahan HDB.