Ten wheat genotypes were tested in a randomized complete block design with three replications under two irrigated and rainfed conditions to identify drought tolerant genotypes. Indices of drought tolerance were calculated based on the potential (Y_p) and under stress (Y_s) yield. Analysis of variance of indices exhibited highly significant differences among the geometric mean productivity (GMP), mean productivity (MP) and stress tolerance index (STI) and non-significant differences between the stress susceptibility index (SSI) and stress tolerance (TOL) indices. This indicates the existence of genetic variation for the attributes studied and the possibility of selection for drought tolerance genotypes. The highest significant positive correlations were found among GMP, MP and STI indices and potential and under rainfed yield. The highest GMP, MP, and STI were related to the TV2 genotypes. Principal component analysis reduced five indices down to two components with 99.49% proportional cumulative variance. Correlation and principal component analysis indicated that the most suitable criteria for the identification of genotypes under irrigated and rainfed conditions were GMP, MP and STI indices. Three dimensional plots exhibited that TV2 was the best drought tolerance genotype. Results of biplot analysis also identified the same genotype as the highest yielding one in both conditions.

Genetic studies of plants are base on high efficiency of purified DNA samples. In this study, we optimized DNA extraction and PCR conditions of Satureja khuzistanica from Iran. The aerial organs of this plant contain high levels of essential oil which makes it difficult to DNA extraction with high quality and thereby intervened with subsequent PCR expansion. Four published DNA extraction protocols include Dellaporta (1983), Doyle and Doyle (1990), Murry and Thompson (1980), Kang and yang (2004) were compared for their capability to produce suitable quality DNA from Satureja khuzistanica. The protocol that provided the foremost DNA quality in the Satureja khuzistanica is selected. In Dellaporta method, no acceptable results were found because SDS buffer extraction was not attached to proteins well. In Doyle and Doyle, the obtained DNA was negligible. In kang and yang method, the quality of extracted DNA was not satisfying. Finally, in modified Murray and Thompson method, the extracted DNA has proper quality. In this method, these factors had the considerable effect on the quality of extracted DNA include: change of incubation time, high NaCl concentration, temperature changes in centrifugation stages, use of proteinase K and TE with high amount of salt and use of plant leaves before flowering stage