RD99 (Hawm Khlong Luang 72), a Non-glutinous Rice Variety

Abstract

Nowadays, although Thai fragrant rice is a large portion of the international market, this fragrant rice is confronted with several challenges including lowering the cost and an increasing production from oversea competitors. In addition, the non-photosensitive rice varieties with soft texture and aroma are limited. The current production relies on photosensitive varieties which limit its growth to the wet season. On the occasion of His Majesty the King Rama 10’s 72nd birthday in the year 2024, Rice Department, led by Chachoengsao Rice Research Center, developed a new fragrant rice variety RD99 (Hawm Khlong Luang 72) that could be an alternative option for farmers to grow in both wet and dry seasons. This variety was renamed from the line number CCS12009-KLG-18-1-1-3-1, which was an outstanding line from the cross between IR841 and Chai Nat 1. This line had been under the processes of yield trials as well as evaluate the resistance to major diseases and insect pests, nitrogen response, physical and chemical properties of grain, milling and cooking quality. It is a non-photosensitive variety, has 115 days from planting to maturity based on the transplanting method, has an average height of 113 cm, and has a moderate response to nitrogen fertilizer (approximately potential yield at 957 kg/rai). The average yield was 780 kg/rai with a high milling quality, which has the total head rice of 50.03%. The length of brown rice is 7.79 mm, 2.22 mm width and 1.80 mm thick considered as slender shape. Seed dormancy of this variety is four weeks. It has excellent cooking quality with a low amylose content of 17.85% and an aromatic quality of 1.69 ppm of 2AP concentration. The quality of cooked rice is soft with moderate stick. It can be qualified as premium grade rice (100%) of export quality. However, it is moderately susceptible to brown planthopper, blast and bacterial blight diseases. It is suitable for planting in irrigated rice production systems in the central and northern parts of Thailand.