Water deficit stress is considered as one of the most important factors affecting soil microbial activities in dry and semi-dry ecosystems, which reduces microbial activity by limiting access to nutrients. To evaluate the effect of water stress (30%, 50%, 70%, and 100% of field capacity), urea chemical fertilizer (100, 200, and 300 kg/ha), and the impact of biological fertilizers (inoculation with mycorrhiza alone, co-inoculation with mycorrhiza and nitrogen-fixing bacteria, co-inoculation with mycorrhiza and azospirillum, and control) on the yield characteristics of Zea mays hybrid Sc706, a field experiment was conducted as a split-split plot in a randomized complete block design with three replications in two cropping seasons (2018-2019 and 2019-2020) on a farm in Firoozabad, Fars province, Iran. Dual and triple interactions of water stress, urea chemical fertilizer, and biological fertilizer showed significant differences in all yield characteristics. In most traits, the application of urea chemical fertilizer (200 and 300 kg/ha) along with biological fertilizers (mycorrhiza-azospirillum and mycorrhiza-nitrogen-fixing bacteria treatments) produced the best results. Overall, it can be concluded that the use of 200 and 300 kg/ha of urea fertilizer along with a combination of biological fertilizers, mycorrhiza-azospirillum and mycorrhiza-nitrogen-fixing bacteria, can be suitable options for improving the yield and morpho-physiological characteristics of corn under regional conditions.

Pearl Millet (Pennisetum glaucum L.) is one of the most important crops in arid and semi-arid regions that are cultivated for grain and forage. Due to cross pollination and high heterosis, the development of hybrid varieties is the most important breeding method of pearl millet. In order to study the preliminary yield comparison of hybrid cultivars and investigate the possibility of replacing open-pollinated cultivars with hybrid cultivars, 11 promising pearl millet hybrid cultivars with a check variety (Mehran cultivar) were planted in the randomized complete block design with three replications in Karaj, Isfahan and Zabul. The days to 50% flowering, plant height, stem diameter, leaves number, panicle length, panicle thickness, tiller number, fresh fodder yield, dry matter yield, 1000 seed weight, and seed yield were evaluated. The results of combined variance analysis and mean comparisons showed that there is considerable genetic diversity for the studied traits. The results showed that the cultivars H294, H444, H504, H604, H824, and H794 had the highest grain yield compared to the total mean of the experiment. In addition, five cultivars H543, H333, H353, H563, and H604 were above of total average in terms of fodder production and had good potential to be used in the field as commercial cultivars with the aim of fodder and seed production.

The development of herbicide-resistant weed species is a threat to the agricultural industry in Iran and the world. The first step in managing this issue is the identification of herbicide-resistant populations. In this study, 124 and 45 grass weed accessions, including winter wild oat, annual ryegrass, and littleseed canarygrass, were collected from wheat and canola fields, respectively, in different provinces of Iran. The accessions were screened using commonly used herbicides at the three- to four-leaf stage. The weed accessions collected from wheat fields were exposed to the recommended field dose of clodinafop-propargyl, pinoxaden, mesosulfuron-methyl+iodosulfuron-methyl-Na, and mesosulfuron-methyl+iodosulfuron-methyl-Na+diflufenican. Similarly, the canola grass weeds were treated with haloxyfop-R-methyl, sethoxydim, cycloxydim, and clethodim. The experiment was carried out based on a completely randomized design with four replications under controlled greenhouse conditions. Four weeks after spraying, the fresh weight of the populations was measured. The results showed that 52, 9, 19, and 17% of grass weeds in wheat fields were resistant to clodinafop-propargyl, pinoxaden, mesosulfuron-methyl+iodosulfuron-methyl-Na, and mesosulfuron-methyl+iodosulfuron-methyl-Na+diflufenican, respectively. Morover, 47, 47, and 22% of the canola grass weeds showed resistance to haloxyfop-R-methyl, sethoxydim, and clethodim, respectively; while they were susceptible to cycloxydim. Cross-resistance to selective herbicides in canola was observed in 36% of the tested grass weed species. Additionally, multiple resistance to both ACCase and ALS inhibitors in wheat fields was identified in 13% of winter wild oat and 82% of annual ryegrass populations, respectively. It is recommended to avoid the use of herbicides with the same mechanism of action for controlling grass weeds in areas where the wheat and canola rotation system is prevalent

In order to compare 25 genotypes of bread wheat in terms of morpho-physiological and biochemical traits, an experiment was conducted in a randomized complete blocks design with three replications in the rainfed and irrigated conditions at Razi University, Iran, in 2016-2017. GT-biplot was used to evaluate genetic diversity and to identify stable genotypes with high yield and drought tolerance. Combined variance analysis showed that there was high variability among genotypes for the most of traits. Examining the correlation of traits in two environmental conditions showed that morpho-physiological traits; especially yield components, were the most related to yield. The results of the GT-biplot method showed that the first and second principal components explain 41.7% and 40.1% of the total changes in rainfed and irrigated conditions, respectively. Based on the GT-biplot analysis diagrams of genotypes 10, 15, 6, 13, 2, 14, and the Pishtaz cultivar in terms of physiological traits, yield and its components and the traits related to stem and spike in irrigated conditions, and genotypes 10, 15, 6, 18, and 17 in terms of biochemical traits, yield and its components, and traits related to stem and spike in rainfed conditions were recognized as superior genotypes. The genotypes 2 and 6 in irrigated conditions and the genotype 6 in rainfed conditions had the lowest genotype×trait interaction. Finally, the genotypes 10, 15, and 6 were superior in two environmental conditions and the genotype 6 had the least interaction effect in both conditions. Therefore, these genotypes can be used in breeding programs.

The present research was conducted to simulate the impact of climate change on irrigated barley in Lorestan and Hamadan provinces. For this purpose, nine regions including Aligudarz, Borujerd, Khorramabad, Kuhdasht, Pol-e Dokhtar, Hamedan, Malayer, Nahavand, and Kabudarahang were selected in the two provinces. The APSIM-barley model was employed to simulate the growth and development of irrigated barley. Firstly, the APSIM-barley model was evaluated using two independent field experiments. The first experiment was conducted in Khorramabad to calibrate the crop model; while the second experiment was done in Hamedan to validate the crop model. The future climate was projected using the AgMIP methodology under two scenarios (RCP4.5 and RCP8.5) for the period 2040-2070. The results of the model validation showed that the crop model was able to simulate barley yield and biomass with nRMSE of 16.4% and 13.3%, respectively. Additionally, the results indicated that on average across the study locations, barley grain yield would decrease by 3.8% and 5.7% under RCP4.5 and RCP8.5, respectively. However, in Pol-e Dokhtar, barley grain yield is projected to increase by 1.3% and 4.8% under RCP4.5 and RCP8.5, respectively. Based on these findings, adaptation strategies should be considered in the future to prevent the reduction of irrigated barley yield in the studied provinces.

Adding organic amendments to the soil increases permeability, water-holding capacity, biological activity, and nutrient content, and consequently increases the soil fertility and the yield of plants. In order to evaluate the effects of municipal waste compost and sheep manure on yield and yield components of wheat, a three-year field experiment was conducted as a randomized complete block design with three treatments, including the application of sheep manure (17.3 kg m-2), compost (15.6 kg m-2), and control (no organic amendment) in three replications in Agricultural Research Station of Zarghan, Fars province, during 2015-2018. The results showed that organic amendments had a significant effect on the number of fertile tillers per area, plant height, ear length, grain number per ear, thousand-grain weight, grain yield, biological yield, and harvest index; however, straw weight was not significantly affected by organic amendments. In all three years of the experiment, sheep manure and compost significantly increased wheat grain yield compared to the control treatment. On average, compost and sheep manure increased wheat grain yield by 63.9% and 46.1% in the first year, 29.3 and 53.7% in the second year, and 37.4 and 26.9% in the third year, respectively, compared to the no-amendment treatment. However, in the most cases, no significant difference was observed between sheep manure and compost. Therefore, farmers can use any of the sheep manure or solid-waste compost to increase wheat yield, the amount of which should be determined based on the amount of organic carbon in the farm soil.

This experiment was conducted to investigate the effect of crop arrangement and different levels of nitrogen on the morphological characteristics, photosynthetic pigments, and nutrients of sunflower seeds, as a split plot experiment in a RCBD design with three replications in 2021. The main plots included five different patterns of spatial arrangement (square, normal rectangle, wide rectangle, triangular, and mixed cultivation systems). Different levels of nitrogen chemical fertilizer (urea) in three levels (application of 100, 75, and 50% of the plant's fertilizer requirement) were placed in sub-plots. The results showed that the maximum leaf width (40.3 cm), leaf area index (4.64), number of leaves (29.2), stem diameter (3.95 cm), and plant height (177.3 cm) were obtained from the treatment of triangular planting arrangement. In addition, the triangular planting arrangement and then the square planting arrangement had the highest content of chlorophylls and carotenoids compared to the other planting arrangements, and the lowest content of chlorophylls and carotenoids were observed in the wide rectangular planting arrangement. Moreover, the results showed that the maximum protein, nitrogen, phosphorus, and potassium of sunflower seeds were obtained in the triangular planting arrangement (17.15, 2.98, 0.54, and 1.73%, respectively), and no significant difference was observed in the triangular planting arrangement between different levels of nitrogen. Generally, the triangular crop arrangement by improving the growth characteristics of sunflower resulted in maximum grain yield and 50% reduction in urea consumption, because the yield of sunflower in the mentioned treatment did not show a significant difference with the application of 100% urea fertilizer; Therefore, the triangular cultivation arrangement is introduced as the best cultivation system for sunflower.

For this purpose and identify the best bread wheat lines in terms of yeild and stability, an experiment was carried out during the two crop years of 2020-2021 and 2021-2022 in the research farm of Safi Abad Agricultural and Natural Resources Research Center, Dezful. 407 new wheat lines were evaluated along with 4 regional control varieties, in the first year & 88 best lines of the first year were evaluated along with Mehrgan and Chamran 2 varieties, in the second year. One of the main reasons for this decrease in yield can be attributed to the increase in the temperature of March in the second year (20 degrees Celsius) compared to the first year (16 degrees Celsius), which caused the average grain filling period from 49.5 days in the first year to reach 46.7 days in the second year. Finally, according to the total measured traits of each line during two crop years, lines No. 384, 365, 356, 383, 355, 389 and 424 were selected as the best lines. Pedigree study of the top lines, it was found that in the pedigree of the top 5 lines, there is a common parent named BORL14, which probably made these lines superior to the other tested lines. According to these results, it is possible to propose and implement the use of this line to improve the wheat breeding program in the hot and dry areas of the south.

Vernalization genes (Vrn), in addition to controlling the growth habit of wheat (spring and winter), play a key role in flowering time and early maturity of wheat. They are also of great interest in drought tolerance researches. To investigate the effect of Vrn genes on drought tolerance, four isogenic lines were developed. Isogenic lines were resulted from the crosses of the early heading Australian variety, Excalibur, with the late heading Iranian variety, Roshan, and followed by backcrossing with Roshan. Two experiments were conducted based on randomized complete block design with four replications under rainfed conditions of Sepidan during 2019-2020 and under well-watered conditions of Kerman during 2020-2021 cropping years. In the present research, seven important agronomic traits, including days to heading, days to ripening, grain filling period, spike number per meter square, grain number per spike, 1000-grain weight, and grain yield were assessed. Isogenic lines were assessed for drought tolerance using eight indices, including mean of productivity (MP), yield index (YI), stress tolerance index (STI ), geometric mean of productivity (GMP), stress susceptibility index (SSI ), yield stability index (YSI), and stress tolerance score (STS). The results of stress tolerance score (STS) showed that isogenic lines vrn-B1/Vrn-D1a and Vrn-B1a/vrn-D1 had the highest and the lowest stress tolerance score, respectively. In addition, the vrn-B1 and Vrn-D1a alleles, which cause early flowering, improve drought tolerance by utilizing an escape mechanism from dry conditions.

In order to investigate the changes in weed flora in the irrigated wheat fields of Isfahan county over a 15-year period (from 2019 to 2004), a systematic sampling of weeds was conducted in 100 farms with W pattern during wheat tillering to stem elongation stages. In 2004, the dominant weed species was winter wild oat (Avena ludoviciana) with a abundance index of 76.1; however, in 2019 three weed species, including winter wild oat, wild barley (Hordeum spontaneum), and littleseed canarygrass (Phalaris minor) were recognized as the dominant species with abundance indices of 70.1, 42.3, and 28.6, respectively. In 2004, the dominant broadleaf weed species were lambsquarters (Chenopodium album) with a dominance index of 67.9 and prostrate knotweed (Polygonum aviculare) with a dominance index of 31.96. However, in 2019, the highest dominance indices were observed in lambsquarters, prostrate knotweed, and Flixweed (Descurainia Sophia) with abundance indices of 78.4, 38.5, and 39.04, respectively. The correlation between weed distribution and soil factors (nitrogen, phosphorus, potassium, soil texture, and electrical conductivity), crop rotation, and herbicides was examined using canonical correspondence analysis (CCA). Littleseed canarygrass, wild barley, field brome (Bromus commutatus), licorice (Glycyrrhiza glabra), hoary cress (Cardaria draba), and yellow sweet clover (Melilotus officinalis) showed the highest correlation with soil nitrogen levels.