Abstract

Drought stress significantly affects rice, a semi-aquatic plant critical for global food security, especially in rainfed areas where yield losses are severe. This study focused on enhancing the drought tolerance of the short-duration rice variety ADT36 through the introgression of qDTY1.1 using marker-assisted backcrossing. Field evaluations were conducted under moisture conditions (MC) (Rabi season, 2022-23) and flood conditions (FC) (Kharif season, 2023). Under MC, the growth rates of the improved lines showed a significant negative difference compared to FC. In the BC3F2 generation, the improved lines exhibited a dwarf phenotype due to the linkage of the sd-1 gene with qDTY1.1, contrasting with the recurrent parent (RP) under MC. However, in the BC3F3 generation under flooding, three recombinant lines (RL-1, RL-3, RL-4) showed increased plant height compared to the RP. Regarding grain yield, there was an increase ranging from 16.3% to 17.8% compared to the RP under MC. Remarkably, under flooding, RL-1 (38.2%), RL-2 (39.6%), RL-3 (42.5%), and RL-4 (21.3%) exhibited significantly higher grain yields compared to MC. This consistent performance of qDTY1.1 in the genetic background of ADT36 suggests these lines are suitable for diverse environmental conditions, highlighting their potential in subsequent trials.

Key words: ADT 36 rice variety, qDTY1.1, Drought stress, Grain yield, Plant height, moisture and flooding.