Evaluation of Drought Tolerance Indices for Selection of Confectionery Sunflower

In order to study the response of 56 landraces of confectionery sunflower to drought stress, an experiment was conducted in the experimental field of Agricultural Research Center of West-Azerbaijan in 2012-2013 cropping seasons. The genotypes were evaluated in three separated rectangular 7 × 8 lattice design with two replications in three irrigation treatments including optimum irrigation, moderate stress and sever stress where irrigation was done after depletion of 50%, 70% and 90% of available water, respectively. Nine drought tolerance indices including mean productivity (MP), stress tolerance index (STI), geometric mean productivity (GMP), harmonic mean (HARM), stress non-stress production index (SNPI), yield index (YI), drought resistance index (DI), modified stress tolerance index in optimum irrigation (MPSTI), and modified stress tolerance index in moderate and severe stress (MsSTI) were calculated based on grain yield under well-watered (YP), moderate drought stress (YS-mild) and severe drought stress (YS-severe) conditions. Grain yield in well-watered (YP), mild and severe stress conditions was significantly and positively correlated with MP, STI, GMP, HARM, SNPI, YI, DI, MPSTI and MSSTI. Results of this study showed that in moderate drought stress conditions the indices MP, STI, GMP and HARM could be used as the most suitable indicators for screening drought tolerant genotypes. Based on cluster analysis, the studied genotypes were grouped in 3 clusters in each one of water treatment conditions. To select drought tolerant genotypes in severe drought stress conditions, it is suggested to use indices MP, STI, GMP, HARM, SNPI and MSSTI because these indices supports stable and high yield in both non-stress and stress conditions.