Evaluation of drought tolerance indices for the selection of Iranian barley (Hordeum vulgare) cultivars
Drought is an important factor limiting crop production in arid and semi-arid conditions. Drought indices which provide a measure of drought based on yield loss under drought condition in comparison to normal condition was used for screening drought-tolerant genotypes. This study was conducted to determine drought tolerant genotypes with high yield in stress and non-stress conditions. Ten barley genotypes were tested in a randomized complete block design with three replications at the Research Centre of Islamic Azad University of Firoozabad, Iran during 2010-2011 growing season. Eight drought tolerant indices mean productivity (MP), stress tolerance index (STI), geometric mean productivity (GMP), tolerance index (TOL), stress susceptibility index (SSI), harmonic mean (HARM), yield index (YI) and yield stability index (YSI) were estimated for each genotype based on yield under stress (Ys) and non-stress (Yp) conditions. There were significant differences for all criteria among the genotypes. The correlation coefficients indicated that MP, STI, GMP and HARM were the best criteria for selection of high yielding genotypes under stress and non-stress conditions. Principal components analysis showed two components which explained 99.66% variation. Based on the results of principal component analysis, biplot and cumulative grain yield diagrams and cluster analysis, Nosrat cultivar was the most tolerant genotype and showed considerable potential to improve drought tolerance in barley breeding programs. Kavir and Nimruz cultivars were identified as high drought susceptibility and low yield stability genotypes.
Key words: Mean productivity (MP), stress tolerance index (STI), geometric mean productivity (GMP), tolerance index (TOL), stress susceptibility index (SSI), harmonic mean (HARM), yield index (YI), yield stability index (YSI).