Drought Field Screening of Rice Genotypes in Drought-prone Rainfed Environment

Abstract

Rice yield significantly reduced due to drought stress in northwest Bangladesh. Drought tolerant rice genotypes could play a vital role to increase rice productivity and sustainability, and improve livelihood of farmers in drought prone rainfed ecosystem. Therefore, the study was undertaken to investigate the responses of rice genotypes under drought prone rainfed environment and to select rice genotypes tolerant for drought stress. A total of 30 rice genotypes were evaluated in drought prone rainfed high Barind tract at Godagari, Rajshahi, Bangladesh (24.27 N latitude, 88.21 E longitude, 40 masl) over two wet seasons (WS) July to December. Twenty five-d-old seedlings were transplanted in 25 x 15 cm spacing @ 3 seedlings hill^-1 following randomized complete block design with 3 replications on 16 August of both the WS. Rainfall, temperature, drought severity, ground water depth, soil moisture content, soil water potential, phenology, leaf  rolling and drying, spikelet sterility, dendogram clustering, rooting behaviors, yield and yield component data were measured to understand drought stress and to evaluate the performance of the genotype. Yield, yield components, leaf rolling, spikelet sterility and root characteristics varied significantly (p=0.001) among rice cultivars. Grain yield and harvest index of the tested rice genotypes ranged from 1.28 to 4.51 t ha^-1 and 0.25 to 0.47, respectively based on drought severity. Across genotypes, 61% root biomass were located in the upper 0-10 cm soil layer, and decreased sharply in the layers below (27, 9 and 3% in the 10-20, 20-30 and 30-40 cm layer, respectively). Based on overall performance under drought stress, four rice genotypes (IR74371-70-1-1, IR83377-B-B-93-3, IRRI123 and IR83381-B-B-6-1) were selected as drought tolerant and BR7873-5*(NIL)-51-HR6 selected as drought escaping. The genotypes IR74371-70-1-1 and BR7873-5*(NIL)-51-HR6 were released as drought tolerant variety BRRI dhan56 and drought escaping BRRI dhan57, respectively. Consequently, the genotypic variation in our germplasm selection indicated considerable scope to develop drought tolerant variety through breeding for improvement of rainfed lowland rice.