a. yazdan sepas

Due to limited water resources in the country, irrigated wheat cultivars in cold and temperate cold regions are faced with lack of irrigation or limited irrigation at the end of the season. In these areas, most farmers who cultivate irrigated wheat due to lack of sufficient water in the spring cannot perform enough irrigation and therefore do not get the desired result from cultivating high-yielding cultivars. Development of new cultivars with high grain yield under terminal drought stress conditions is one of the major goals of wheat breeding program for cold regions of country. Heyran new bread wheat cultivar introduced from International Research Center for Maize and Wheat (CIMMYT) to Iran through an international nursery in 2010 and was evaluated in a primary trial in four research stations (Karaj, Jolge-Rokh, Ardabil and Mashhad), and due to its favorable characteristics was selected for further evaluation in preliminary yield trials in cold regions. This line showed grain yield of 8417 kgha-1 under normal irrigation compared to the check cultivars Orum, Zareh and Mihan (with average yields of 7679, 6828 and 7772 kgha-1, respectively), and under terminal drought conditions with an average seed yield of 4653 kgha-1, compared to the check cultivars Orum, Zareh and Mihan (with average yields of 4375, 3544 and 4358 kgha-1, respectively) and was selected in both conditions. Aforementioned line showed grain yield of 8340 kgha-1 in advanced yield trial of cold regions breeding program under normal conditions compared to check cultivars Orum, Zareh and Mihan (with average yields of 7518, 7613 and 8205 kgha-1, respectively) in five locations, selected for final evaluation in adaptability test. Grain yield of this line which was presented as CD-92-6 at the adaptability test was 4470 kgha-1 against 3711 and 3743 kgha-1 of Zareh and Mihan checks cultivars under water stress conditions, respectively, during two cropping seasons 2013-14 and 2014-15. This line showed overall mean grain yield, of 5143 kgha-1 under terminal drought stress conditions in extensional farmer’s fields. For these conditions checks cultivars Hydari and Mihan showed grain yields of 4808 and 4758 kgha-1, respectively. Grain yield potential of this line was recorded as 6323 kgha-1 in Khorasan Razavi farmers' field. According to the latest evaluations the response of this line to yellow rusts was resistant to semi sensitive under severe artificial infection. Wheat line CD-92-6 has considerable cold tolerance and good bread making quality and based on its good agronomic characteristics in 2019 this line was released as Heyran, for cultivation under terminal drought stress conditions in the cold agro-climatic regions.

Genetic and environmental factors can affect the performance of the genotypes. Genotype ×environment interaction could be result different reaction of the genotypes in different environments. Therefore، determination of stability of the genotypes in different environments is the most important. In this study 15 winter and facultative bread wheat genotypes (including two check cultivars) were used. This experiment was conducted in 11 research stations in cold regions in 2003-04 and 2004-05 cropping seasons. Experiments design was randomized complete block (RBCD) with three replications. Based on results of combined analysis of variance، effect of year، location، genotype and genotype × year interaction effects were found non-significant. However، location ×year، genotype ×location and، genotype × location ×year interaction effects were significant. Based on stability parametric methods such as coefficient of variability (CVi%)، Shukla stability variance (σi2)، simultaneous selection for yield and stability (YS)، and non-parametric method of ranking genotype C-82-12 (Fdl4/Kauz) with average grain yield of 7035 kg ha-1،YS=18، R=5. 86، SDR=3. 427non-significant stability variance (σi2) and low environmental CV was identified as high yielding and stable genotype.

Sepahan is a new bread wheat cultivar derived from progenies of a cross made between Azadi cultivar and some high yielding and resistant to rust advanced lines. All selections were made in Kelardasht and Iranshahr stations and early evaluations in Karaj. It was also studied in regional uniform yield trials in moderate stations including Kaboutar Abad. Results revealed that this line is more tolerant to drought, thus it's suitable for arid areas of Iran and it has higher yield than check cultivar (Mahdavi). It is of spring habit and early maturity, 95-100 cm plant height, grain color amber and thousand kernel weight of 40 gram. Sepahan has grains with average protein and gluten content 10.3% and 23% respectively. Based on these superiorities and good performance, the new line was released in 2006, under the name of Sepahan

Development of wheat cultivars with high and stable yield for different environments is very important in breeding programs. In this study, 19 winter and facultative wheat genotypes along with a check cultivar (c.v. Shahreeyar) were studied for grain yield and its stability at Karaj, Arak, Ardebil, Hamedan, Mashhad, Jolgeh Rokh and Tabriz Agricultural Experimental Stations in 1997-2000 cropping seasons. The experimental design was RCB with four replications. Results of combined ANOVA showed that interaction of genotype x location x year was highly significant. Using different stability analysis methods such as CV, regression analysis and simultaneous selection for yield and stability showed similar results. Genotype C75-5 (OWL 85256*-3oh-*O-*Eoh) was determined as the superior for grain yield among all genotypes in almost all methods. Results of the study on harvest index (HI) indicated that the genotype C-75-15 (Bez- 2B/Cgn/Vratza) was superior for HI stability. Although, the correlation coefficient between grain yield and harvest index was positive and significant (r =0.36**) however, stabilities of these two traits among the genotypes, were not similar.

In order to study the response of different winter and facultative wheat (T. aestivum L.) genotypes to terminal drought stress, this experiment was conducted in the Experimental Field of Cereal Research Department, Seed and Plant Improvement Institute at Karaj in 1999/2000 and 2000/2001 cropping seasons. Twenty winter and facultative wheat genotypes were evaluated in two separate experiments, one with non-stress and in the other one, stress was applied from anthesis to physiological maturity. A randomized complete block design with three replications was used. Results of combined analysis of variance of grain yield showed significant difference between genotypes. Genotype x year and genotype x irrigation interactions were significant at 5% probability level, however, genotype x irrigation x year was not significant. Stress tolerance index (STI), stress susceptibility index (SSI), geometric mean productivity (GMP), mean productivity (MP) and tolerance (Tol) were calculated based on the grain yield of the genotypes in both conditions. Among the genotypes number 8 (Pck/Vee) was outstanding. Grain yield of this genotype in non-stressed and stressed conditions was 9320 and 7079 kgha-1, respectively. MP, GMP, STI and SSI for this genotype were 8200 kgha-1, 8123 kgha-1, 0.85 and 0.98, respectively. Results showed that correlation coefficients between STI, GMP and MP indices and grain yield (under both conditions) were positive and highly significant, therefore, these indices can be used to identify high yielding and tolerant genotypes under non-stressed and stressed conditions. Finally, using cluster analysis based on indices and grain yield (in both conditions), genotypes were classified in five groups.