In Thailand, rice are cultivated on the rainfed unbunded upland environment about
0.928 million ha annually, which usually subject to drought stress due to an eratic rainfall
throughout growing season, and usually having low yield stability and productivity. Two
experiments were characterized a drought tolerant-related physiological traits, yield and its
components of 6 elite landrace upland rice cultivars (Niaw Dum Luem Phua, Dawk Pa Yawm,
hukaothong 2, Sew Gliang, Sam Deuan, and Leb Nok) with IR1552, and Khao Dawk Mali 105,
a moderate drought-tolerant check varieties. The first experiment was carried out at King
Mongkut’s Institute of Technology Ladkrabang, Bangkok during Aug-Sep 2018 for 4 drought
tolerant-related characters at maximum tillering including longest root, root dry weight,
root/shoot dry weight ratio, and stomatal conductance. The germinated seeds were grown in a
cylindrical like-shape plastic pots, data were recorded for 10 hill/experimental unit. The second
experiment was conducted at the experimental field of Rajamangala University of Technology
Tawan-Ok, Chon Buri province, on loammy-sand, unbunded upland field under natural rainfed
in rainy season (Jul-Nov), 2018. Ungerminated seeds were directly planted with space of 25x25
cm, yield and yield components were sampling recorded for 10 hill/experimental unit. All
studied characters among cultivars; longest root, root/shoot dry weight ratio, stomatal
conductance, yield and all yield components except, root dry weight were highly significant
different (p≤0.01). IR1552 had the highest yield of 72.52 g/hill. Among 6 landrace cultivars,
Niaw dum luem phua showed the highest drought tolerant-related characters, yield components,
and rough yield of 59.77g/hill. While, Khao Dawk Mali 105 had rough yield of 51.42 g/hill.