RD57 (Pathum Thani 200), a Non-glutinous Rice Variety

Abstract

Irrigated rice cultivation in the central region and the lower northern region often face the problem of infestation of brown planthopper, which always causing a damage to the rice yield. In addition, the climate condition of these rice growing areas during the winter time is usually cold. The temperature would continuously drop during the flowering stage, causing unfertile grains which leads to unfilled grains and reduced yields. It is, therefore, necessary to develop rice varieties as an alternative to farmers. The objective of this research was to improve non-photoperiod sensitive rice varieties, which are resistant to brown planthopper, tolerant to cold weather, and high yield, in order to be released to farmers for use in irrigated paddy fields. The research activity was carried out by a crossbreeding between Suphan Buri 1 (brown planthopper resistant) and IR64 cultivars. Pure line selection activities, observation trials, and evaluation trials have been carried out from the F₂ to the F₆ generation and the line SPR94007-PTT-27-2-9-3 has been obtained. Research activities have been carried out at Pathum Thani Rice Research Center from 1994-2014 following the crop improvement steps, i.e., yield trials, yield stability, yield performance in the areas with brown planthopper outbreaks, yield performance under a low temperature condition, evaluation on rice diseases and insect pests, response to nitrogen fertilizer, analyses for grain physical and chemical qualities, milling quality, cooking and eating quality, and an evaluation of farmers’ acceptance. The promising line was finally approved by the Varietal Releasing Committee of the Rice Department to be a certified variety, “RD57” (Pathum Thani 200). It is a non-glutinous, non-photoperiod sensitive rice variety with 87 days to 50% flowering (broadcasting method), 117-120 days to harvest (transplanting method), erect plant type, moderately strong stem, 115-120 cm height, dark green leaf color, 57 cm leaf length, 1.6 cm leaf width, 25.7 cm panicle length, 94-123 fertile seeds per panicle (broadcasting method), and 83% seed fertility rate. RD57 has an average yield of 714 kg/rai under farmers’ field condition. It has a straw-colored paddy with a paddy grain size of 10.75 mm in length, 2.54 mm in width, and 2.01 mm in thickness.  Its dehulled grain has a white color and a slender shape, with a grain size of 7.41 mm in length, 2.23 mm in width, and 1.90 mm in thickness.  It has low chalkiness (0.84) and good milling quality. It has high amylase content (27.33 percent). Newly harvested milled rice when cooked has a crumbly appearance, slightly shiny, and off-white color. The eating quality of cooked rice is hard and not fragrant. Its distinctive features are that it is quite resistant to brown planthoppers in the central region and the lower northern region, resistant to cold weather at a minimum temperature of 14 °C, high yield (714 kg/rai), and good yield stability. It has a high yield potential (1,169 kg/rai), suitable for cultivation in irrigated fields. Caution should be taken as this variety is relatively susceptible to leaf blast, bacterial leaf blight and rice ragged stunt diseases.