In order to determine the best indices for drought resistance, 20 wheat lines were compared in a randomized complete block design with four replications under drought and normal conditions. In the study, five indices including: Stress Tolerance Index (STI), Stress Tolerance (TOL), Stress Susceptibility Index (SSI), Mean Productivity (MP), and Geometric Mean Productivity (GMP) were used. The indices were adjusted based on grain yield under drought and normal conditions. The best index was the one that caused yield increase under both normal and stress conditions. STI and GMP were found to be the best indices for drought resistance selection. Regarding these criteria, the line 5784 was the most resistant line. Germination test by -0.6 Mpa osmotic potential polyethylene glycol showed that, there was a significant difference in germination stress index (GSI) among wheat lines. Also, GSI was positively correlated with GMP and STI. Thus, this trait might be used as a good criterion prior to conducting a field screening for drought tolerance at a large scale, thus saving field experimental costs. The rolled blotter test revealed that GSI was positively correlated with coleoptile length and root weight. Therefore, the longer the coleoptile with greater the root weight, the higher drought resistance would be.
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