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

Sunflower is one of the most important oilseed crops with more than 50% of nutritional (table) consumption. Considering the climate changes, the development of genotypes tolerant to abiotic stresses is more important than before. In the present research, the recovery capacity of two oilseed sunflower genotypes (DM-2 and H158A/H543R) was evaluated 24 hours after irrigation following sever drought stress (30% of field capacity) by evaluating the changes in enzymes activity at 8-leaf stage and quality and quantity of end product at adult plant stage. The experiments were conducted in frame of completely randomized design with 3 replications under controlled conditions. A significant difference was observed between genotypes in the terms of guaiacol, ascorbate, lipoxygenase and proline contents, as well as leaf area, leaf length, root weight, plant height and root sodium-potassium ratio in recovery conditions. Based on the results of the evaluations and changes in the mean of traits in the comparison of two normal and recovery conditions, as well as the pattern of fatty acids, genotype DM-2 has a high recovery ability.

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.

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.