RDH1, a Non-glutinous Hybrid Rice Variety

Abstract

Thailand rice production has been facing problems about the low average of yields across planted areas as compared to other rice exporting countries. High yielding variety such as hybrid rice is used as a method to increase rice productivity in many countries. Therefore, research was conducted to develop high yielding hybrid rice as farmers’ choice for increasing yields in irrigated paddy areas. PTT06001H is a hybrid (F₁) derived from three-line breeding method where IR79156A male sterile line with the corresponding IR79156B maintainer line was used as female parent and JN29-PTT-43-1-5-5-1-3-1R restorer line as male parent. The male parent was developed from F₂ to F₇ pedigree selection of JN29 hybrid variety to obtain JN29-PTT-43-1-5-5-1 line followed by two generations of further selection. Research have been carried out by Pathum Thani Rice Research Center during 2002 to 2009 through the following crop improvement steps, i.e., studies of combining ability and heterosis, comparison of yield and yield stability, evaluation on resistance to rice disease and insect pests, response to N fertilizer application, analyses for grain physical and chemical quality, milling quality and cooking and eating quality. The promising line was subsequently approved by the Varietal Releasing Committee of the Rice Department to be a certified variety, “RDH1”. It is a photoperiod-insensitive and non-glutinous rice with 115 days to harvest, erect plant type, 116 cm height, strong culm, light yellow internode, dark green leaf, erect leaf angle, purple lines on leaf sheath, erect flag leaf, just exserted panicle, intermediate panicle type, 29 cm panicle length, 8 panicles per hill, and 200-250 healthy seeds per panicle. RDH1 has average farmer field yield of 929 kg/rai, straw-colored paddy, white dehulled grain, slender grain shape, less chalkiness, high amylose content (27.53 percent), low gelatinization temperature and crumbly cooked rice. Remarkable features are high yield (929 kg/rai) with 14 percent higher yield than Pathum Thani 1 (813 kg/rai), resistance to rice blast in central, eastern and western regions, and moderately resistance to whitebacked planthopper. It is recommended to be grown in irrigated paddy fields in the central and lower northern regions. Caution should be taken as this variety is susceptible to brown planthopper and bacterial leaf blight and moderately susceptible to blast disease in the lower northern region.