Improving the nutritional status of plants is an effective method for enhancing their ability to withstand drought stress. To evaluate the quantitative, qualitative, and antioxidant properties of castor plant under water deficit conditions stress and foliar application of chemical fertilizers, an experiment was conducted as a split-plot design in a completely randomized block design with three replications. The first factor was irrigation levels including control (normal irrigation), irrigation after 80 mm and 140 mm evaporation from the pan evaporation in the main plots, and eight spraying chemical fertilizers (sulfur, potassium, nitrogen, sulfur+potassium, sulfur+nitrogen, potassium+nitrogen, sulfur+potassium+ nitrogen and control (no spraying)) were included in subplots. The highest proline content, catalase, peroxidase, superoxide dismutase, and total phenol were obtained under irrigation after 140 mm of evaporation conditions and foliar application of nitrogen+potassium+sulfur. Also, the highest grain yield, oil yield, and the lowest oil percentage were observed in the nitrogen+potassium foliar treatment under irrigation conditions after 20 mm of evaporation. Although the content of malondialdehyde increased in water deficit stress treatments, nitrogen+potassium+sulfur and nitrogen+potassium foliar application significantly reduced the peroxidation of membrane lipids (malondialdehyde) under irrigation conditions after 80 and 140 mm of evaporation compared to the control treatment. In conclusion, foliar application of chemical fertilizers in castor can improve the resistance to water stress by strengthening the antioxidant system and then increase its grain and oil yield.

This research was carried out in order to evaluate the biochemical and agronomic traits of dryland chickpea intercropped with dragon’s head in Saqqez city (Kurdistan province). It was conducted as a factorial split-plot experiment, arranged in a randomized complete block design, with three replications during the 2021-2022 cropping year. Treatments included three planting times (autumn, expecting, and spring) as first factor, three chickpea cultivars (Saral, Nosrat, and Anna) as second factor and five cultivation patterns [(pure chickpea), (25% L. iberica: 100% chickpea), (50% L. iberica: 100% chickpea), (75% L. iberica: 100% chickpea), and pure L. iberica cultivation (100% L. iberica). The highest leaf chlorophyll a and b contents were obtained in winter with intercropping of %100 Nosrat chickpea + %50 L. iberica and planting ratio (%100 chickpea +% 25 L. iberica), respectively. The highest leaf carotenoid content was obtained in spring with planting ratio of %100 Saral chickpea + %75 L. iberica. The highest water use efficiency was obtained in winter, in the Nosrat variety, and in pure cultivation. The land equivalent ratio in all intercropping patterns was more than one, which showed the superiority of L. iberica and chickpea intercropping compared to pure cropping.

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.