Abstract
Drought stress is one of the most significant environmental factors restricting plant production all over the world. In arid and semi-arid regions where drought often causes serious problems, wheat is usually grown as a major crop and faces water stress. In order to study drought tolerance of wheat, an experiment with 34 genotypes including 11 local and commercial cultivars, 17 landraces, and six genotypes from International Maize and Wheat Improvement Center (CIMMYT) was conducted at the experimental station, School of Agriculture, Shiraz University, Iran in 2010-2011 growing season. Three different irrigation regimes (100%, 75% and 50% Field Capacity) were applied and physiological and biochemical traits were measured for which a significant difference was observed in genotypes. Under severe water stress, proline content and enzymes’ activities increased while the relative water content (RWC) and chlorophyll index decreased significantly in all genotypes. Of these indices, superoxide dismutase (SOD) and RWC were able to distinguish tolerant genotypes from sensitives. Moreover, yield index (YI) was useful in detecting tolerant genotypes. The drought susceptibility index (DSI) varied from 0.40 to 1.71 in genotypes. These results indicated that drought-tolerant genotypes could be selected based on high YI, RWC and SOD and low DSI. On the whole, the genotypes 31 (30ESWYT200), 29 (30ESWYT173) and 25 (Akbari) were identified to be tolerant and could be further used in downstream breeding programs for the improvement of wheat tolerance under water limited conditions.
Highlights
Drought stress is known to be the most important environmental factor that limits plant’s growth and production (Kirigwi et al, 2004; Almeselmani et al, 2011) and has been a great threat to wheat production worldwide
The highest and lowest relative water content (RWC) contents belonged to genotypes number 20, 8, 2 and 29, 25, 5, 3 under normal condition, genotypes 28, 24, 19, 1 and 22, 21, 17 under 75% FC drought stress, and genotypes 28, 24, 19 and 33, 22, 13, 2 under 50% FC drought stress, respectively
Genotypes with high drought susceptibility index (DSI) and low yield index (YI) were sensitive to drought
Summary
Drought stress is known to be the most important environmental factor that limits plant’s growth and production (Kirigwi et al, 2004; Almeselmani et al, 2011) and has been a great threat to wheat production worldwide. It is vital to understand wheat’s response to drought stress throughout growth stages to mitigate its detrimental effects. Drought stress responses are altered by changes in the expression level of various compatible solutes/osmolytes and the reactive oxygen species (ROS), which in turn affect plant at morphological, physiological and biochemical levels (Shinozaki et al, 2007; Sheoran et al, 2013). Chances are there that genotypes may respond differentially under moderate to severe water stress at a similar growth stage. During drought stress, plant water relations play a key role in the activation and/or modulation of the antioxidant defense mechanism (De Carvalho, 2008). Change in activities of antioxidant enzymes under drought stress depends on plant species, genotype and stress intensity and duration (DaCosta and Huang, 2007)
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