Abstract
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 x 8 lattice design with two replications in three irrigation treatments including optimum irrigation, moderate stress and severe 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 the 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 support stable and high yield in both non-stress and stress conditions.
Highlights
Sunflower (Helianthus annuus L.) is one of the 67 species in the genus Helianthus
To investigate suitable drought tolerance indices for screening confectionery sunflower landraces under drought stress conditions, different indices were calculated based on grain yield under stressed and non-stressed environments (Tab. 6 and 7)
A suitable index must have a significant correlation with grain yield under both non-stress and stress conditions (Mitra, 2001)
Summary
Two main types of sunflower are grown: for oilseed production and nonoilseed or confectionery types (Salunkhe et al, 1999). Confectionery sunflower produces large seeds with low oil content and is used in baking and snack applications (Lu and Hoeft, 2007). The confectionery type is one of the most popular and important crops in Iran. It is cultivated in all parts of the country especially in the northwest regions. Abiotic stresses such as cold, salinity, heat and water stress is the principal cause of crop failure worldwide which dipping average yields by more than 50% (Jaleel, 2007)
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