Screening the Responsible Impact of Fourteen Bread Wheat (Triticum aestivum L.) Genotypes against Osmatic Water Stress Mediated through PEG6000 in Terms of Seed Germination and Early Seedling Growth Stage in Search of Promising Drought Tolerant Genotypes under in vitro Condition | Asian Journal of Research in Biosciences

Seed germination is considered one of the first and critical fundamental life stage of a plant. So, the success in growth and yield production is depending on this stage. A way to overcome the negative effects of deficit water stress on plant production is development of drought tolerant genotypes. With this view an in vitro experiment was attempted to measure and quantify the negative effects of osmatic PEG6000 stress on seed germination and early seedling growth stage of fourteen wheat genotypes to determine the relevant response of studied genotypes with identifying resistant genotypes toward high stress of PEG6000. To achieve this purpose, the experiment was assigned in a split plot arrangement in two factorial CRD fashion projection with three replications under five levels of PEG6000 factors (Ψs) {0% (0 Mpa), 5% (-0.3 Mpa), 10% (-0.6 Mpa), 15% (-0.9 Mpa) and 20% (-1.2 Mpa) w/v} to establish artificial drought stress to assess the progressive effect. The observations are converted into its effects in terms of fifteen biological attributes included (germination percentage, germination index, seedling length, relative percentage of seedling length, reduction percentage of seedling length, seedling fresh weight, relative percentage of seedling fresh weight, reduction percentage of seedling fresh weight, seedling dry weight, relative percentage of seedling dry weight, reduction percentage of seedling dry weight, tissue water content, vigor index, tolerance index and coefficient of relative inhibition). The experiment was repeated for confirmation and the results were similar. The results appeared that the germination percentage was not found as effective indicator of genotypic variation for PEG6000 stress at early seedling stage. Moreover, degree of PEG6000 stress tolerance at early seedling growth stage did not maintain in all studied wheat genotypes. Therefore, the authors were done PCA plots and Euclidean distance analysis to distinguish and clear superiority PEG6000 stress-tolerant genotypes. Overall, genotypes Gimeza-12, Sakha-94, Katela, and Sids-12 are relatively drought tolerant genotypes as they showed a better performance degree of survival on high levels of induced PEG6000 and the remaining genotypes had an intermediate response toward the induced PEG6000. This method can be recommended as a tool for determining the mechanisms to the plant breeder for suitable rapid detection criteria of screening drought tolerant genotypes in a large population incorporate with the reduced cost and labor to initiate breeding programs to develop better drought tolerant genotypes as a best parents for genetic characterization through QTL analysis of mapping population derived from them.

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