RD89 (Num Ban Sang), a Non-glutinous Rice Variety

Abstract

Floating rice varieties are vital in paddy fields where the surface water level is more than 100 centimeters deep and the prolonged flooding lasts for more than 2-3 months. There is no other type of rice varieties or other crops that could be planted and give desirable yield as good as floating rice in the above mentioned areas. However, most floating rice varieties, including those rice varieties certified by the Rice Department are usually high amylose content varieties, crumbly rice once cooked, not suitable for direct consumption, but suitable for processing. This research activity was, therefore, conducted in order to obtain rice varieties with low amylose content, high yield in paddy fields with the water depth more than 100 centimeters, good seed quality, good cooking and eating quality. The breeding cross was made between the rice lines PCR92211-5-2-2B and PCRC93021-67 and the 1^st generation population; PCR02032, was obtained. Mass selection was carried out in the early generation populations and a pedigree selection was carried out in the 5^th and 6^th generation populations. The line PCR02032-4B-24-1 was finally obtained. Research has been carried out at Prachinburi Rice Research Center from 2002-2021 through the following steps; yield trials, evaluation on agronomic characteristics, elongation ability, resistance to rice diseases and insect pests, response to nitrogen fertilizers, analyses of grain physical and chemical quality, milling quality, cooking and eating quality, as well as the acceptance of farmers and rice buying entrepreneurs. The selected promising line was approved by the Varietal Releasing Committee of the Rice Department to be a certified variety, “RD89 (Num Ban Sang)”. It is a photoperiod sensitive, non-glutinous rice variety which flowers during 18-23 November and is ready to be harvested by late December. Its’ plant height was 221 cm. It has erect plant type, moderately strong stems with good ability of internode elongation at the surface water level of 150 cm, green leaf color, and slow leaf senescence. It has mostly compact panicles with 27.72 cm in length and 149 fertile seed per panicle. An average yield from farmers’ fields was 450 kg/rai. RD89 has straw-colored with brown spots husk. Its’ paddy grain size was 10.54 cm in length, 2.68 cm in width and 2.12 cm in thickness. It has white dehulled grain and slender shape with 7.58 cm in length, 2.22 cm in width and 1.86 cm in thickness. It has low chalkiness (0.71) and very good milling quality. For grain chemical quality, RD89 has low amylase content (15.32%) and soft gel consistency. Its cooked rice has normal grain elongation ratio, off white color, and was moderately sticky, soft and non-aromatic. Its distinguishing features are that it has a good potential of internode elongation under the condition with the surface water level more than 100 cm deep, high yield (450 kg/rai), low amylase content (15.32%) and soft cooked rice. It is recommended to grow in the areas with a prolonged flooding of more than 1 month and the surface water level more than 100 cm deep, especially the paddy fields for floating rice in Prachinburi and Nakhon Nayok provinces or areas with similar agricultural ecosystem. Caution should be taken as this variety is susceptible to leaf blast, bacterial leaf blight, bacterial leaf streak, and very susceptible to brown planthopper.