Evaluation of Drought Tolerance in Rice Recombinant Inbred Lines Using Stress Tolerance Indices

To evaluate drought tolerance in rice recombinant inbred lines obtained from a cross between two cultivars of Ahlami-Tarom (tolerant) and Sepidrood (susceptible), a field experiment was conducted in spring 2016 in the research farm of Gonbad Kavous University. One hundered sixteen genotypes were studied using randomized complete block design with three replications in two environments (drought stress and non-stress conditions). MP, GMP, STI, RDY, HM, K1STI and K2STI indices had high correlations with grain yield under the two environments (drought stress and non-stress), therefore were identified as suitable indices for selecting drought-tolerant lines. A biplot analysis perfermed based on the first and second components of principle component analysis showed that lines No. 12, 112, and 113 were the most tolerant, and lines No. 43, 50, 64, and 89 were sensitive genotypes. Moreover, biplot also identified SNPI and SSPI suitable for identifying tolerant genotypes to drought stress. Grouping of lines based on 17 drought tolerantce indices and grain yield in the stress and non-stress conditions was performed by cluster analysis using Ward method, and four clusters were formed. The second and fourth clusters, with the highest and lowest K2STI, included the most tolerant and most sensitive genotypes to drought stress, respectively. Overall, according to the biplot and cluster analyses, lines No. 112 and 64 were identified as the most tolerant and most sensitive genotypes, respectively. Grain yield of line No. 112, in the drought stress and non-stress conditions was 5190 and 6640 kgha-1, respectively. However, grain yield of line No. 64, in the drought stress and non-stress conditions were 1640 and 2240 kgha-1, respectively.