j.jafarzadeh

Wheat (Triticum aestivum L.) is important in the food regime of three-quarters of the world's population because it is nutritious and cheap compared to other similar foods. The competition between wheat and weeds is considered as one of the most important limitations of global wheat production. In Iran, weeds are of particular importance in reducing wheat yield, and according to the surveys, the average damage caused by weeds in the country's wheat fields is 23%. The most common way to manage wheat weeds is herbicide application. Every crop resists herbicides at a given growth stage, otherwise, herbicide application will damage the main crop. In recent years, the most frequent broadleaf herbicides used for weed chemical control in wheat are 2-4-D + MCPA (U46 combi fluid). To apply the 2,4-D herbicide, wheat should be at the tillering to the appearance of the first visible node stage. Application of 2,4-D after the first node will cause spike deformation and yield reduction due to the adverse effect of herbicide on sporogenesis. This study investigated different application times effects of 2-4-D + MCPA (U46combifluid) and Bromoxynil + MCPA (Bromicide MA) on winter wheat yield and weed control. The study aimed to determine the application time of the best herbicide with minimal damage on dryland wheat.

To investigate the effect of hormone herbicides on weeds and the yield of dryland bread wheat in different vegetative growth stages in cold dryland areas, a field experiment was conducted as a randomized complete block design arrangement with four replications during 2021-23 cropping seasons at the Dryland Agriculture Research Institute, Maragheh, East Azerbaijan. Treatments included the application of 2-4-D + MCPA (U46combifluid) and Bromoxynil + MCPA (Bromicide MA) (1.5 L ha-1) at the tillering (Z29), the 2nd   node (Z32), and the booting stages (Z45) with two control treatments of weeding (weed infested) and no weeding (weed free). The Varan wheat cultivar was sown at a depth of 4–6 cm with a seeding density of 380 seeds per square meter. To evaluate weed type and density (plant m-2), sampling was done 30 days after herbicide application. The crop was harvested at full maturity to collect data for grain yield and a thousand grain weight and grain/spike. After checking the normality of the data, they were analyzed with GenStat (V.12) software and the mean comparison was performed by the Least Significant Difference (LSD) test at the 5% probability level.

The results indicated that the weed growth time is affected by the rainfall in dryland conditions so that in the 2021-2 year, the main spring precipitations occurred in May while in the 2022-23 year, it happened in April. Therefore, for the first cropping season, the highest weed density was recorded in the second   node stage whereas at the tillering stage in the second cropping season. In the first year, due to lower rainfall, and drought stress, a further decrease in wheat yield was observed in response to the delayed herbicide application so that it was higher in the 2-4-D + MCPA herbicide treatment. In the 2021-22 year, the lowest yields were recorded for 2-4-D + MCPA and Bromoxynil + MCPA herbicides in the booting stage with 1568 and 1710 kg ha-1, respectively. In the 2022-23 year, the lowest grain yield was observed for 2-4-D + MCPA in the second node, and booting stages, respectively, 1701 and 1747 kg ha-1.

Based on the results, wheat is more sensitive to delayed application of 2-4-D + MCPA and reduces wheat yield more, in contrast, it is more tolerant to bromoxynil + MCPA herbicide (Bromicide MA), and it can be applied up to the 2nd node stage (Z32).

Kamal, is a new winter bread wheat cultivar developed by the national rainfed bread wheat breeding program for the cold and temperate dryland areas of Iran. New cultivar created by crossing between Sbn//Trm/k253 and 88Zhong218//Ctk/Vee/3/Kvz/Gv//Prl in Maragheh Research Station. Kamal was selected from segregating population from F2-F7 in Maragheh (2002-2008) based on agronomic characteristics. Based on results, Kamal grain yield means in preliminary and advanced regional yield trail was 2234 and 1719 kgha-1, respectively. Results of elite trail in cold and moderate research stations (2012-2015) showed that the grain yield mean of Kamal was 2120 and means of Azar2 and Ohadi cultivars were 2066 and 2083 kgha-1, respectively. Kamal cultivar in East Azerbaijan province was compared with conventional control cultivars in the farmer fields for 3 years and the results showed that the average grain yield of Kamal and checks were 2604 and 2230 kgha-1 respectively. Kamal is a winter type variety with time to heading of 143 days, 67 cm plant height, 40, gr. 1000 kernel weight, 11.4% protein content, 20 ml Zeleni numer, 41 degree of hardness, 27% wet gluten and 15 unit of gluten index. Results revealed that Kamal cultivar is tolerant to cold and drought stresses, with suitable earliness, and good bread quality but susceptible to yellow rust and leaf rust, this xultivar way and released in 2019 under the name of Kamal for cold and moderate cold dry areas of Iran.

Drought-tolerance and grain yield stability are among the most important aspects in adaptation and successful performance of rainfed winter bread wheat cultivars. The main objectives of this study were (i) to assess the effectiveness of drought tolerance indices for selection of drought-tolerant winter bread wheat genotypes, and (ii) to identify high-yielding genotypes with yield stability in variable environments. In this experiment, 24 winter bread wheat genotypes were evaluated in 12 yield trials under two moisture-regimes (rainfed and supplemental irrigation) in two dryland research stations differing in winter temperature (temperate and cold agro-climatic conditions) during three cropping cycles (2018-2021). Yield-based drought tolerance indices including; stress tolerance index (STI), geometric mean productivity (GMP), mean productivity (MP), tolerance index (TOL), stress susceptibility index (SSI) and yield stability index (YSI) were used to estimate drought tolerance levels of winter bread wheat genotypes across locations and cropping cycles. GGE-biplot technique was used for grain yield stability analysis. Combined-analysis of variance revealed that the main effects of cropping season, location, moisture-regime, genotype, and their interactions effects on grain yield were significant (P<0.01). The combined and yearly PCA-based biplots and correlation matrix analyses revealed that STI, GMP and MP were consistently correlated (P<0.01) with grain yield in either rainfed and irrigated environments, indicating the effectiveness of these indices for selection of high-yielding genotypes in both conditions. Based on these indices, G13 (Chenab/GB-SARA-27 IRW2009-10-023-0MA-0MA-0MA-0MA-0MA-6MA), G14 (Chenab/GB-SARA-27 IRW2009-10-023-0MA-0MA-0MA-0MA-0MA-7MA), G11 (Dharwar Dry/Nesser//SARA-BW-F6-06-85-86-2-5 IRW2009-10-056-0MA-0MA-0MA-0MA-0MA-6MA) and G22 (Unknown-2) were the most drought-tolerant genotypes. GGE-biplot analysis identified G11, G13 and G14 as high yielding genotypes with yield stability across environments. In conclusion, the genotypic variation for drought tolerance and grain yield stability found in this study should be further explored in the national rainfed winter bread wheat breeding programs in Iran.

To study drought tolerant in rainfed winter bread wheat genotypes, 48 genotypes (lines and cultivars) were evaluated under two rainfed and supplementary irrigation conditions at Maragheh research field station, Maragheh, Iran, in2018-19 and 2019-20 cropping cycles. The results of combined analysis of variance showed that effects of years, genotypes and year × genotype interaction on day to heading, day to physiological maturity, grain filling duration, plant height, 1000-grainweight, biological yield, grain yield and harvest index were significant. The average grain yield of genotypes under rainfed conditions was 1707 kg ha-1. The highest grain yield under rainfed conditions related to genotypes no. 4, 23, 20 and 26, respectively, with 2080, 2066, 2035 and 1999 kgha-1.under supplementary irrigation conditions genotypes No. 13, 7, 11 and 25 with 3044, 3014, respectively, with 2943 and 2914 kgha-1 had the highest grain yield. Supplementary irrigation increased mean grain yield by 738 kg ha-1, mean plant height by eightcm, mean 1000 grain weight by three grams and mean harvest index by four percent. Drought stress reduced grain yield of all genotypes. No significant correlation was observed between grain yield of genotypes under rainfed and supplementary irrigation conditions. Positive and significant correlations were observed between MP, GMP, HM, STI and YI with grain yield (Ys) under rainfed and supplementary irrigation (Yp) conditions which indicated the suitability of these indices for selection of genotypes with reasonable grain yield under either conditions. Based on the results of principal component analysis and three-dimensional diagram, genotypes 20, 23 and 26 were identified as drought tolerant genotypes with reasonable yield in both rainfed and supplementary irrigation conditions. Genotypes 13, 7, 11, 25 and 32 were also identified suitable for supplementary irrigation conditions.

Wheat is the most important staple food crop in the world as well as in Iran. About 63% of the wheat cultivation areas and 40% of its production is under dryland conditions in Iran. Water and nitrogen are the two most important limiting factors for wheat production in dryland conditions. However, the role of water is about 2.3 to 3.9 times the nitrogen because the water deficiency limits the absorption of the nutrients especially nitrogen. Nitrogen deficiency is very critical than the other nutrients for plant growth in the arid and semi-arid region. Therefore, applying supplemental irrigation (wherever it is possible) at the critical crop growth stages along with nitrogen fertilizer will increase wheat production by increasing the greenness and photosynthetic activity of the plant. In this regard, the cereal department of Dryland Agricultural Research Institute (DARI) has introduced different new wheat cultivars for supplementary irrigation conditions in the last decade. Hence, evaluating the response of bread wheat genotypes to different rates of nitrogen under supplementary conditions, determining the relationship between nitrogen requirement and water status of varieties as well as the relationship between these factors with yield components and effective traits to improve the quantity and quality of the crop, are the key factors for wheat production in dryland areas.

A field experiment was conducted to evaluate the response of dryland wheat (Triticum aestivum L.) genotypes to different rates and timing of nitrogen application under supplemental irrigation in 2018-2020 cropping seasons at DARI, Maragheh, Iran. The experimental design was a randomized complete block with three replicates based on split-split-split plot arrangement consisting of two irrigation treatments (50 mm in planting time and 50 mm in planting time + 30 mm at booting stage) in the main plot; nitrogen application time (fall application and split 2/3 in planting time + 1/3 in booting stage) in the sub-plot; four nitrogen rates (0, 40, 80 and 120 kg.ha−1) in the sub-sub-plot and three genotypes (Takab, Hoor and Griset-16 (sup-96-18) in the sub-sub-sub plots. The soil samples were collected from 0-25 cm depth before the sowing and were determined soil texture (loam to silty clay), pH, EC, Organic carbon, P (Olsen method), K (Sodium bicarbonate method), micronutrients (Fe, Mn, Zn, and Cu) by DTPA method. Because all these elements were more than critical levels (P: 10 mg.kg-1; K: 250 mg.kg-1; Fe: 5 mg.kg-1; Mn: 11 mg.kg-1; Zn: mg.kg-1 and Cu: 1.4 mg.kg-1) in the soil, only nitrogen rates were used in the experiment (Feiziasl et al., 2004; Feiziasl et al., 2009). The data was collected for biological and grain yield, yield components, plant height, spike length, nitrogen use efficiency (NUE), water use efficiency (WUE), and seed quality (Seed protein, Number of Zeleny Grain hardness, Grain starch). The GenStat14 software was used to combined analysis of variance and mean comparison of traits by Duncan's Multiple Range Test. The CurveExpert 2.6.3 software was used to fit equations, Excel to draw charts and Xlstat2016 software to do principal component analysis.

The first year of the experiment produced a significantly higher yield (P≤0.05) due to higher precipitations. Two stages of supplementary irrigation significantly increased biological yield, grain yield, and straw yield by 2975, 895, and 2069 kg ha-1, respectively. Although fall and split application of nitrogen had no significant effect on yield and yield components, fall application increased grain yield, NUE, and WUE by 195 kg.ha-1, 1.97 kg.kg-1, and 0.5 kg.ha-1.mm-1, respectively. Nitrogen application increased grain yield components for which the number of spikes per square meter was increased more than the two others. The nitrogen requirement of dryland wheat was determined 70 kg.ha-1 under single irrigation at planting time by fertilizer placement method while it was determined 90 kg.ha-1 for two stages supplementary irrigation for which 2/3 of it was applied at fall (planting time) and 1/3 at booting stage with supplementary irrigation.

 Although the interactions of irrigation, nitrogen rates, application times, and genotypes factors on grain yield were not significant, supplemental irrigation and nitrogen application could increase the yield production of dryland wheat genotypes.

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.

The reaction of forty two barely landraces, mostly from Azarbijan Province and a susceptible cultivar, Zarjo, was studied under greenhouse conditions in the presence of four highly virulent isolates of Pyrenophora graminea, i.e. Marand 3, Ajabshir 2, Khasseban-Tireh, and Bostanabad. The experimental design was a split-plot based on randomized complete blocks with three replications. Landraces were considered as sub-plots and the isolates as whole plots. The seeds were inoculated by the sandwich method and responses of the landraces were evaluated by the method of Mathur and Bhatnagar. The resistance of landrace #1 to the isolates of Marand 3 and Ajabshir 2 and that of landrace # 27 to the isolate of Ajabshir 2 was observed. These landraces could be used as a source of vertical resistance in barley. Landraces 6, 8, 11, 12, 13, 15, 17, 25, 27, 28, 29, 31, 33, 34, 36, 37 and 41 were classified within the range of partial resistance to partial susceptibility, which may be utilized as the sources of horizontal resistance.