Abstract
In order to compare different rice genotypes grown under drought stress conditions a field experiment was conducted. In this study thirty different genotypes of native, breeded and upland cultivars were evaluated. Analysis of variance showed significant differences among genotypes in respect of all vegetative and morphological traits. Genotypes were devided into three groups by cluster analysis based on all studied traits with minimum variance method (Wards Method). The total average indicates significant differences among groups in respect of all morphological and physiological characteristics. In addition, eight drought stress tolerance indices including: sensitivity to stress index (SSI), drought response index (DRI), relative drought index (RDI), tolerance index (TOL), mean productivity index (MP), stress tolerance index (STI), geometric mean productivity index (GMP) and harmonic mean index (HM) were calculated according to their grain yield under drought stress and normal conditions. In general, results of this experimnet revealed that, among rice cultivars Domsephid, Deylamany, Hasansaraei, Sadri, Anbarboo and Domsiah had the highest sensitivity referring to drought stress and produced the lowest grain yield. Also, genotypes of IR24 (breeded of IRRI), Nemat, Sephidroud, Kadoos and Bejar (breeded of Iran) and Vandana, upland cultivar (originally from India) had the highest tolerance to drought stress and produced the highest grain yield. In conclusion, it was suggested that, these cultivars are suitable for drought stress conditions and are appropriate for hybridization with the aim of increasing drought tolerance.
Highlights
From the beginning of agriculture, drought stress is one of the most important factors, causing famine and death by its influence on plant productions
Considering the results, dwarf cultivars showed good resistance to drought stress which is caused by more assimilates transfer to panicles
Tolerance to high stress in dwarf cultivars resulted from their smaller size and their growing period
Summary
From the beginning of agriculture, drought stress is one of the most important factors, causing famine and death by its influence on plant productions. There are five main reasons of the importance of drought stress; its unpredictablity, the way of occurance, intensity, time and duration of drought. Interaction between drought stress and other abiotic stresses such as high temperature and changes in nutrition availability limits plant growth and development. Drought stress is a multidimensional stress that affects different plant growth stages. Drought stress or lack of water is limited to arid or semi arid areas, and sometimes, due to irregular distribution of rain, causes unfavorable conditions for plant growth and development. It’s obvious that drought stress causes significant decrease of plant yield (Kumar and Singh, 1998)
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