RDJ1, a Japonica Non-glutinous Rice (Wang Tawng 72)

Abstract

Consumption of japonica rice in Thailand has noticeably increased at about 15-20%. However, the limitation of production is not only covering of climate in northern Thailand, but also the japonica rice varieties. DOA1 and DOA2 are only two varieties that have been commercially grown more than two decades though their susceptibility to leaf blast, leading to insufficiency for domestic consumption. Recently, a new japonica, non-glutinous rice variety has been developed by Chiang Rai and Phitsanulok Rice Research Centers that adapt to the climate of northern Thailand. A single cross between PSL95037-25-1-2-Pan-1 as a female parent and a tropical japonica Shubu as a male parent was made at Chiang Rai Rice Research Center in 2012 followed by the early stage of progenies selection. The varietal development processes, the evaluation for yield, disease and insect resistance, nitrogen response and other agronomic characteristics have been conducted. In addition, the properties of grain and cooking quality have been improved according to the consumers’ requirements. An outstanding line, CRI12026-6-9-PSL-4-1-1-1, was selected from many lines that were included in the evaluation processes during 2015-2020. This line has been accepted by The Thailand Rice Variety Board and agreed to release as RDJ1 (Wang Tawng 72). RDJ1 is a japonica, non-glutinous rice variety, photoperiod insensitive with maturity of 89-113 days (wet season) and 105-123 days (dry season), having erect clump and moderately stiff stem with a plant height of 93 cm. The average yield is 755 kg/rai while its potential yield of 953 kg/rai. This new variety has straw color paddy with awn, no seed dormancy and paddy length of 7.65 mm. It has bold shape of brown rice, non-aroma with low amylose content (17.31%), low chalkiness and high milling recovery (65.50% milling head). It is resistant to leaf blast but susceptible to brown planthopper and whitebacked planthopper. RDJ1 is suitable for planting under irrigated rice area in upper and lower northern regions of Thailand. However, planting under the suitable condition of lower northern rice area may shorten its maturity.