Field Evaluation of RD6 Introgression Lines for Yield Performance, Blast, Bacterial Blight Resistance, and Cooking and Eating Qualities

Glutinous rice cultivar "RD6" is well known for its fragrance and high cooking and eating qualities, and is the most popular glutinous cultivar in the north and northeastern regions of Thailand. However, it's susceptible to blast and bacterial blight (BB) diseases. Previously, four blast resistance QTLs on chromosomes 1, 2, 11, and 12, and a single BB resistance gene xa5 pyramided to the background of the RD6 cultivar were tested for a broad spectrum of disease resistance under greenhouse conditions. In the present study, a field experiment was conducted during the rainy seasons of 2015, 2016, 2017, and 2018, across three locations, for performance evaluations of promising lines in terms of disease reaction, agronomical characteristics, grain yield, and quality attributes. The results revealed that the ILs (BC2F5 2-7-5-36, BC2F5 2-7-5-43, BC2F5 2-8-2-25, and BC2F5 6-1/15-2-11) exhibited higher level resistance to leaf blast and neck blast disease. The BC2F5 2-8-2-52 showed resistance to both blast and BB diseases and, like all ILs, exhibited superior yield compared to the original RD6. Furthermore, the agronomic traits and grain qualities were similarly displaced, and were therefore recommended as near-isogenic lines to the RD6. This clearly demonstrated that farm phenotypic selection plays an important role in achieving not only NIL resistance to diseases, but also high yield potential, as well as representing an effective way in which to enhance BB, leaf blast, and neck blast resistance in rice planting in the north and northeastern regions of Thailand.