RD33 (Hawm Ubon 80) Rice Variety

Abstract

More than 80% of farmers in upper north and northeastern parts of Thailand prefer to grow KDML 105 and RD15 rice varieties because of their good cooking quality and meet market demand. But these 2 varieties are susceptible to blast disease, about 30% yield loss caused by this disease. Therefore, breeding new variety which is resistant to rice blast and having good cooking quality like KDML 105 was conducted in 1995. KDML 105 variety used as female parent cross with IR70177-76-3-1 (blast resistance) used as male parent at IRRI, the Phillipines. Breeding line 1R77924-UBN-62-71-1-2 selected from this breeding program which has been proved from the breeding committee of Rice Department, named "RD33 (Hom Ubon 80)". This variety had been tested for crop yield and other quality by comparing with KDML 105 and RD15 from inter-station yield trials and on-farm yield trials including nitrogen response, yield stability, resistant to brown planthopper, bacterial leaf blight and blast diseases, physico-chemical properties, cooking quality, organoleptic test (eating quality) and farmers' acceptance during 1986 - 2005 ( 10 years). It was found that RD33 is non-glutinous rice, photoperiod - insensitive, average height 154 cm, harvesting date 130 days, average yield 528 kg/rai. Its brown rice is white color with length, width, and thickness are 7.47, 2.11 and 1.80 mm respectively, less chalkiness (0.98), good milling quality, low amylose content (14.0-16.8 %), gel elongation ratio 1.4, aromatic rice variety closed to KDML 105. The prominent property is resistant to many pathogenic races of rice blast fungus (Pyricularia grisea Sacc.). RD33 is suitable for growing in rainfed area (late part of rainy season) in northeastern and upper north parts. Since RD33 is rather susceptible to bacterial leaf blight and brown planthopper therefore, care must be taken when growing in the area prone to these disease and insect pest.