فهرست مطالب s. mahfoozi

In order to produce wheat lines with high tolerance to drought and cold stresses, Sadra variety was generated by a cross between Sardari (male) and promising line Azadi/Azar (female) in Maragheh research station. Results of studies in the cold and moderate cold research stations showed that the grain yield means of Sadra, Azar2 and Sardari cultivars were 2394, 2332 and 2214 kgha-1, respectively, so that grain yield of Sadra was 8% and 3% higher than Sardari and Azar2 check cultivars, respectively. Sadra has a good adaptability to different climatic conditions, so that the new cultivar possess a great potential to be more productive during years with higher precipitation. According to the results, the mean grain yield of Sadra, Azar 2 and Sardari cultivars under optimal rainfall conditions were 3330, 3045 and 2522 kgha-1, respectively. Sadra cultivar has good general adaptability and grain yield stability, winter growth habit, high tolerance to cold and drought stresses, date to heading of 137 days, plant height of 80 cm and 1000 kernel weight of 35 gr. One of the most important characteristics of Sadra is its bread-making quality, so that Sadra with Zeleni number of 33, protein content of 11.3%, hardness of 47, wet gluten content of 30, gluten index of 50 and SDS sedimentation volume of 55 has a great bread-making quality. Based on its high yield potential and other appropriate agronomic characteristics, Sadra cultivar was released for cultivation in the cold and moderate cold dryland conditions of Iran.

Release of new wheat cultivars with good characteristics such as high yield performance and resistance to diseases for specific regions under rainfed condition is an essential task for sustainability of wheat production. Saein was generated by crossing between: Azar2 and 87Zhong291 (with facultative growth type, high yield performance, good thousand kernel weight and resistance to diseases) in 1999-2000 in Maragheh Research Station. Grain yield means of Saein and Azar2 (as check cultivar) during 2006-2013 cropping seasons in Maragheh Research Station were 2601 and 2493 kgha-1 under rainfed condition and 3529 and 3223 kgha-1 with a supplementary irrigation at the sowing time, respectively. Results showed that Saein had also a specific adaptability in Ardabil regions and grain yield means of Saein (new cultivar), Ohadi and Azar2 (as check cultivars) in Ardabil were 1604, 1267 and 1355 kgha-1, respectively. Results of an on-farm study, in the farmer field in Ardabil province, showed that grain yield means of Saein and Azar2 during 2013-2014 cropping season were 2307 and 2275 kgha-1, respectively. The new cultivar is resistant to yellow rust, resistant to moderately resistant to leaf rust and also resistant to common bunt and dwarf bunt as well as resistant to cold damage, lodging and seed shuttering. New cultivar has winter growth type, white grain color, 76 cm plant height and 33 gr 1000 kernel weight. Based on its good characteristics, this line was released as a new wheat cultivar with the commercial name of Saein in 2015 and was recommended for cultivation in rainfed regions in Ardabil province, in the cold dryland areas in the north west of Iran and also in areas with the potential of supplementary irrigation.

The process of adaptation to cold is an important mechanism in wheat cultivars to tolerate cold stress. This work was aimed to calrify the relationship between vernalization requirement with cold tolerance by assessing physiological changes in cold susceptible spring and tolerant winter wheat (Triticum aestivum, cvs. Kohdasht and Cheyyene, respectively) in environmentally controlled conditions, using factiral experiment on the basis of completely randomised design (CRD). By using final leaf number (FLN) method, the vernalization saturation and by using LT50, the level of cold tolerance were determined in both wheat cultivars. FLN results verified no vernalization requirement in Kohdasht and vernalization saturation in Cheyyene at 42nd-d of exposure to 4°C. The results of LT50 proved the maximum cold tolerance on either 42nd-d in Cheyyene (-17°C), or -2°C in Kohdasht (fixed at cold treatment period). The relationship of cholorophyll fluorescence, chlorophyll content (SPAD), proline and total carbohydrates with cold tolerance were studied. The results indicated that cholorophyll fluorescence was less influenced in Cheyyene than in Kohdasht in response to cold stress. Vernalization cold caused significant 30% decline in chlorophyll content in Kohdasht and 36% increase in Cheyyene cultivar on vernalization saturation time (day 42). At this time, 3- and 2-fold cold-induced accumulations of proline and total carbohydrates, respectively were detected in Cheyyene compared to Kohdasht cultivar. In conclusion, such physiological results verified the advantageous response to cold of vernalization required-cultivar in comparison with non-vernalization required-cultivar.

To compare three wheat genotypes for producing the haploid and doubled haploid through chromosome elimination, an experiment was carried out using F1 population from the crosses Raptor×Pishtaz, Norstar×Pishtaz and Mironovskaya×Pishtaz. Measured traits were seed set percentage, embryo and haploid seedling development and were analyzed statistically using χ2 test. Among three genotypes, there was significant difference concerning the percent of seed and embryo forming, but significant difference was not observed for haploid plant. Raptor×Pishtaz showed the highest value for seed set, Mironovskaya×Pishtaz the highest value for haploid plants and embryo forming percent, and Norstar×Pishtaz the lowest level of haploid plants and embryo forming percent. According to the results, the seed set and embryo number traits, when the same number of florets are pollinated, can be considered as an important trait in genotype selection for production of doubled haploid plant. This experiment also showed the dependence of chromosome elimination trait to genotype