Potential for Drought Tolerance and Yield of a Landrace and Recommended Thai Upland Rice Cultivars

Abstract

     Upland rice usually has low stability of yield due to erratic rainfall throughout the growing season. However, drought tolerant cultivars may produce higher yield stability. Two experiments were conducted to evaluate the potential for drought tolerance and yield of 11 landraces and the Thai upland rice cultivars Baguio, IR1552, and Khao Dawk Mali 105. Drought tolerance was assessed at 40 days after planting (DAP) using the following characteristics: longest root,  root dr wt, root/shoot dr  wt ratio,  and stomatal conductance.   Completely Randomized Design   (CRD) with 3 replications was used at the King Mongkut’s Institute of Technology Ladkrabang, Bangkok, and upland field testing for yield was carried out at the Rajamangala University of Technology, Tawan-Ok, Chon Buri province, during the rainy season of 2019 (Aug-Dec), and Randomized Complete Block Design (RCBD) with 3 replications was used. Data were sampled and recorded for 10 hills/unit. The results showed that the Baguio cultivar had the highest drought tolerance potential with the longest root (50.00 cm), highest root/shoot dry wt ratio (0.61), and lowest stomatal conductance (1.39 mmol m-2s-1). The IR1552 and Khun Wang cultivars came 2nd and 3rd, and had longest roots of 44.10, 43.23 cm, root/shoot dry wt ratios of 0.53 and 0.51, and stomatal conductances of 1.41 and 1.43 mmol m-2s-1, respectively. Sew Gliang had the lowest drought tolerant index. Under drought stress due to low and erratic rainfall with loamy-sand, Baguio had the highest rough yield of 139.13 g/hill, Pa-yah Leum Gaeng had the 2nd rank of 78.67 g/hill, and Khao Dawk Mali 105 had 51.42 g/hill.