ahmad tobeh

Ajwain (Carum copticum L.) is a medicinal herb from the Apiaceae family that is widely cultivated in Europe, Iran, India, Egypt, and Pakistan. Pharmacological and clinical trials indicate that C. copticum is effective in treating pharyngitis, showcasing benefits like antioxidant, antiparasitic, expectorant, and antilithiatic effects. Although this herb can withstand damage from water stress, regular and sufficient watering will increase its yield. Inadequate water supply, particularly in terms of quantity and allocation throughout growth and developmental stages, leads to reduced achievement of the crop's intrinsic potential, eventually decreasing the farmer's production and livelihood. Water deprivation is a major limiting factor in semi-arid and arid regions, affecting all aspects of plant morphology, physiology, growth, development, and yield. Chitosan facilitates the formation of secondary compounds like polyphenolics, flavonoids, and lignin, which are beneficial for various herb species, and for the activation of herb defense enzymes. Humic acid can especially influence the growth of medicinal herbs by affecting cell membrane permeability, metabolic pathways, cellular respiration, photosynthetic efficiency, enzyme activation, and cell growth. Melatonin improves plant tolerance against various environmental stresses, including extreme temperatures, cold, salinity, chemical compounds, heavy metals, and pathogens. The use of selenium improve photosynthesis, antioxidant activity, carbohydrate accumulation, and synthesis of secondary metabolites under drought stress. Therefore, this study aims to assess the effects of stress modifiers; namely chitosan, humic acid, melatonin, and selenium on the physiological and yield traits of ajwain when exposed under water stress.

A two-year field trial was performed in the 2022 and 2023 years of cultivation at the University of Mohaghegh Ardabili in Ardabil, Iran. The experimental design was factorial, using a complete randomized block design with three replications. The factors were the stress modulator treatment (MEN: melatonin, CHN: chitosan, HUC: humic acid, and SEM: selenium and CON: control) and irrigation treatments (watering at 100%, 75%, and 50% field capacity (FC) as normal,  moderate deficit irrigation and severe deficit irrigation, respectively). All plots consisted of 8 rows of herbs spaced 20 cm from each other, with plants spaced 40 cm apart within each row. Seeds of ajwain (Carum copticum L.) were sown on March 20, 2022 and 2023. During the vegetative phase of ajwain, foliar spraying was applied on the leaves in the three stages at ten-day intervals, coinciding with periods of moisture stress. Weeds were carefully controlled when needed.  The soil was collected from a depth of 0-30 cm, analyzed, and found to be silty clay (36% Silt, 33% Clay, 31% Sand) with an electrical conductivity of 0.37 dS /m, pH of 7.8, 1.04% of organic matter, 0.11% total N, 10.04, and 344 mg kg−1 available P and K, respectively. A 2-year investigation analysis of variance (ANOVA) was conducted operating the general linear model (GLM) (SAS 9.1.3) combining the findings from 2022 and 2023. The LSD trial was evaluated for comparing means at p < 0.05.

The results showed that under normal irrigation conditions, ajwain plants sprayed with melatonin had the seed yield (733.35 kg/ha), and essential oil yield (22.11 kg/ha). The maximum absorption of nitrogen, phosphorus and potassium (3.09%, 0.40%, and 1.65%, respectively) was obtained under normal irrigation conditions and foliar spraying with melatonin. While the highest amount of total phenol and flavonoid (29.55 and 3.33 mg/g dw, respectively), DPPH radical inhibition percentage, nitric acid radical inhibition percentage, and superoxide radical collection capacity were 78.85, 67.88, and 138.47% respectively, which were observed in the conditions of severe stress and foliar spraying with melatonin. Also, melatonin foliar application improved the amount of essential oil of ajwain (3.30%) under medium stress conditions. Water stress hinders plant growth and development by impacting many physiologic processes, including nutrient absorption, stomata function, transpiration rate, sugar synthesis, hormone production, assimilation, and photosynthesis. Stressful environments were shown to accelerate the synthesis of EOs, as evidenced by the increased EO content under stress. This is likely due to the role of secondary metabolites in helping plants withstand ecological stresses. The application of MEN, CHA, HUM, and SEM directly enhanced photosynthetic pigments, improved photosynthetic efficiency, increased the concentration and activity of RuBisCo, and promoted ATP and NADPH production to enhance plant productivity. Drought stress triggers the production of secondary metabolites and essential oils, which act as protective molecules against environmental pressures. The biostimulant composition, which includes macro and microelements, vitamins, amino acids, and growth hormones, plays a crucial role in promoting plant growth, as well as the percentage and yield of essential oil. When soil moisture availability is restricted, the uptake of water, the solubility of minerals in the soil, and their absorption by roots decline, leading to adverse effects on photosynthesis and transpiration rates. In these circumstances, as previously demonstrated, the foliar application of MEN, CHA, HUM, and SEM positively influences stomatal opening adjustment and chlorophyll abundance, facilitating the growth, division, and elongation of herb root cells. As a result, foliar spraying of MEN, CHA, HUM, and SEM likely maximized this influence by reactivating various biosynthetic and biological pathways and genes that regulate secondary metabolite production, while also enhancing the glands that manufacture essential oils in the flowers and leaves of plants under water restriction. Since hydrocarbons are required as precursors for the production of phenols, an increase in their rate and concentration influences the enhancement of phenolic combinations. Applying MEN, and CHA has been shown to be beneficial in reducing the impact of free radicals and increasing the production of phenolic compounds. This effect may be related to the role of MEN, and CHA in improving antioxidant activity against ROS.

Overall, among all the tested stress modulators, MEN and CHN emerged as valuable tools for improving growth, physiological characteristics, essential oil, and fixed production in ajwain herb. They can help reduce the detrimental impacts of water stress and establish a sustainable framework for optimizing ajwain performance even under moisture-deficit conditions in semi-arid and arid regions of Iran.

Water deficit is one of the most important factors limiting plant production in arid and semi-arid regions of Iran. Potatoes are highly sensitive to drought stress at all stages of development, especially the tuber formation stage. Using genotypes that are adaptable and tolerant to water deficit is one of the main methods of preventing the reduction of agricultural production in arid regions. This study aimed to select drought-tolerant genotypes by examining water use efficiency, tuber yield, tuber weight per plant, and some potato quality traits including dry matter, starch, and protein of 20 potato genotypes in the Ardabil region. 

In order to select drought tolerant genotypes, an experiment in the form of a randomized complete block design with split strip blocks in three replications during the two cropping years 2018 and 2019 in Ardabil region accomplished. Horizontal treatments included 20 potato genotypes and vertical treatments included drought stress and no stress.In order to select droughttolerant genotypes, an experiment in the form of a randomized complete block design with split strip blocks in three replications during the two cropping years 2018 and 2019 in Ardabil region accomplished. Horizontal treatments included 20 potato genotypes and vertical treatments included drought stress and no stress. Genotypes were obtained from the Ardabil Agricultural and Natural Resources Research Station based on ten-year selection in terms of yield and quality.  Each plot consisted of four lines of four meters in length with a distance between the lines and on the lines of 75 and 25 cm, respectively (64 plants in each plot with an area of 12 square meters). To prevent lateral penetration of moisture, a distance of one and a half meters was considered between adjacent plots, and at the time of harvesting, the effect of the margin was minimized by removing the two side lines and the first and last plants in each row. In both years, sowing was carried out on the sixth day of May.

The results showed that stress treatment caused a significant reduction in tuber weight and tuber yield in all genotypes. The highest tuber weight per plant and tuber yield with the lowest decrease compared to the control belonged to genotype 905675 and the lowest value of these traits belonged to Marfona cultivar with the highest percentage decrease compared to the control. In addition, starch content, dry matter percentage and protein content were inversely related to potato tuber yield and increased. The results showed that among the studied genotypes under stress conditions, genotype 901375 had the highest percentage of dry matter and genotype 901375 had the highest percentage of starch. The highest water use efficiency under stress conditions was related to genotype 905675 with a yield of 9.89 kg / m3. In terms of stress indices, genotypes 901375, 905676 and 901675 with the highest numerical values in all four evaluated indices had a high potential for tolerance under stress conditions, respectively. Potato yield is primarily directly related to the amount of water consumed and is strongly affected by drought stress, and the stability of yield under stress conditions depends on the tolerance of genotypes. For this purpose, a numerical ranking between one and 20 was performed to select the genotypes more favorably. Accordingly, the highest and lowest tuber yield, the lowest and highest percentage of change in stress and non-stress conditions were ranked one and 20, respectively. The lowest total rank belonged to genotypes 905675, 901575, and 901375, respectively, which were tolerant genotypes, and the highest total rank belonged to cultivars Milva, Marfona, and Jelli, respectively, which were identified as sensitive cultivar. Under stress conditions, the highest productivity (9.89 kg/m3) was related to genotypes 905675 with a 50% increase, followed by 901375 (9.84 kg/m3) with a 35% increase. The lowest productivity was related to the Marfona variety with 5.66 kg/m3, and the lowest increase under stress (17%) occurred in the Mileva variety. The results showed that the 901375 genotype had high productivity in both non-stressed and stressed conditions. In this experiment, it was found that water use efficiency increased differently in the genotypes by applying stress. This confirms that the higher water use efficiency for potato genotypes under drought stress conditions is an indicator that these varieties have a higher potential for higher yield even under low moisture levels, thus making them suitable for drought conditions.   

In general, considering the rate of changes in tuber yield, tuber weight per plant, as well as increasing starch, dry matter, protein content and water productivity and stress indices, genotypes 905675, 901575 and 901375 in both stress and non-stress conditions, respectively were selected as tolerant and high yield potential genotypes. Therefore, these genotypes can be introduced as a suitable alternative to the well-known cultivar Agria in Ardabil region as well as Milva, Jeli and Marfona cultivars were introduced as susceptible cultivars.

The present research was conducted in order to investigate the effect of cover crops in density and different planting dates on weed control and soybean yield. The experiment was conducted as a factorial design in the form of a randomized complete block design with three replications during growth seasons of 2020-2021 and 2021-2022 in the research farm of the Agricultural and Natural Resources Research and Training Center of Ardabil Province (Moghan). The studied factors include the date of planting cover crops in two levels (at the same time and three weeks after soybean planting), their planting density in two levels (recommended and triple recommended) and the type of cover crop in 12 levels (including autumn barley, oats, autumn rye, autumn wheat, berseem clover, Persian clover, crismon clover, yellow sweet clover, red clover, annual alfalfa, chickling pea and hairy vetch). Also, two control treatments were considered in the form of pure soybean cultivation (without cover crop cultivation) along with spraying and without spraying against weeds next to each replication. The variance analysis of the data showed that the simple and intraction effect of the study treatments was significant in most of the traits. The lowest density of weeds was related to the treatment of hairy vetch in between the rows of soybeans in the second year and on the second date (at the rate of 5.78 plants per square meter), which was achieved with the berseem clover treatment in It was a common statistical group. The lowest amount of weed biomass was also obtained in the treatment of berseem clover among soybean rows on the second planting date and the triple recommended planting density of 3 grams per square meter. All the cover crops studied had the highest biomass on the first sowing date and the triple recommended.. berseem clover with the highest biomass production (137.02 grams per square meter) was ranked first. The highest percentage of soybean oil was obtained in the second year and on the first date and the second density (23.79%). Among the cover crops, the cultivation of hairy vetch among the rows of soybeans, due to its fast growth and greater adaptation to the region, minimal competition with the main plant and also better control of weeds, causes a greater increase the plant height, biological yield, seed protein percentage, seed yield and soybean harvest index were measured. Finally, the maximum yield of soybeans was obtained on the second planting date and triple recommended density in the cover crops of the hairy vetch at the rate of 3616 kg per hectare.  Therefore, it is recommended to use this cover crop in order to achieve the goals of sustainable agriculture in these areas.

One of the environmentally friendly methods of weed control in cropping syastems is using of cover crops. Cover crops can reduce or control weeds through different mevhanisms such as physical suppression (suffocation of weeds), ecological suppression (competition for limited resources of nutrients, water, and light), and chemical suppression (emission of allelochemicals).

To investigate the effect of monoculture and intercropping of cover crops on weed control and grain yield and yield components of corn (Zea mays L. cv. Kousha), a randomized complete block design with four replications was used in the research farm of faculty of agriculture and natural resources of Mohaghegh Ardabili University in ardabil, Iran, in 2018-9 and 2019-20. The experimental treatments included: triticale (×Triticosecale Wittmack) and daikon radish (Raphanus sativus var. Longipinnatus) as monocultures, intercropping of triticale + daikon radish with a control treatment (without cover crops).

The results showed positive effect of triticale monoculture on reducing the density of lamb’s quarters (Chenopodium album), pigweed (Amaranthus retroflexus), and wild mustard (Sinapis arvensis) weeds by 36.7%, 50% and 53.8%, respectively. The highest grain yield (3782.5 kg.ha-1) and number of grain.ear-1 (444.8) of maize were obtained in triticale monoculture. The results showed that triticale monoculture had the most desirable weed control efficiency index (44.1), Simpson index (0.61), Shannon-Wiener index (1.33) and Margalef’s species richness index (1.21).

Based on the results of this experiment, the success of the intercropping of triticale and daikon radish on controlling weeds density and improving maize grain yield was related to suitable density of the plant species used in this experiment. Triticale monoculture, grown in winter, can be considered as an effective cover crop for weed control and improving maize grain yield in Ardabil and similar environmental conditions.

Plants are affected by adverse environmental conditions. One of these environmental factors is cold stress, which is one of the main factors limiting the growth and productivity of agricultural products. One of the effects of cold stress is damage to photosynthetic pigments. So that the cold stress causes the light energy absorbed by the pigments cannot be used in photosynthetic reactions. As a result, this light energy causes photo-oxidation reactions and ultimately causes the loss of photosynthetic pigments. To protect plants from freezing in agriculture, it is possible to foliar application of chemical and natural compounds on plants before they are exposed to low temperatures. Anti-freezing compounds are easily absorbed by the plant and participate in all metabolic processes of the plant. This mechanism allows the plant to reserve some of its energy and thus be resistant to environmental stresses. In addition to anti-freezing compounds, the state of nutritional elements in the plant plays an important role in increasing the capacity of plants to deal with environmental stresses such as salt stress, drought, cold, etc. One of these nutritional elements is potassium, which plays a very important role in reducing the effects of various abiotic stresses such as drought, salinity, metal toxicity, high and low temperatures, etc. Potassium plays key roles in many physiological and biochemical processes such as photosynthesis, protein synthesis, synthesis and transfer of sugars, activation of more than 60 types of enzymes, regulation of osmotic and ionic potassium, and regulation of opening and closing of stomata. Potato (Solanum tuberosum L.) is an herbaceous plant of the Solanaceae family, which is the fourth most important crop in the world in terms of yield and production volume and is used for food, forage, industrial and seed purposes. The appropriate combination of variety and planting date in crops is one of the most important effective factors in adjusting the harmful effects of climate change on the yield of crops.

This research was conducted as a split-factorial design in the form of a randomized complete block design with three replications at the Ardabil Agricultural and Natural Resources Research Station during the two crop season of 2018-2019 and 2019-2020. The investigated factors include planting date in two levels (August 1 and 11), antifreeze compound in two levels (foliar application with water as a control and foliar application with a mixture of frezzebon amino acid + potassium) and potato genotypes in 10 levels including (901375, 901475, 902375, 8708-7, 8709-106, 7009-3, 905675, 8707-26 genotypes and Agria and Savalan cultivars). Furthermore, before the spraying treatment, samples were taken from the experimental treatments and frozen using liquid nitrogen and stored in a freezer.After 24 hours of freezing, the samples were again collected from the experimental treatments and rapidly frozen using liquid nitrogen before being transferred to the laboratory for measurement of the desired characteristics.After collecting the samples, laboratory experiments were conducted at the Faculty of Agriculture of Ardabil University of Medical Sciences and the Agricultural and Natural Resources Research Station in Ardabil.

According to the results, it was determined that foliar application of frezzebon amino acid combined with potassium increased plant height, tuber weight per plant, content of photosynthetic pigments, vitamin C, soluble sugars, tuber starch percentage and tuber dry matter percentage. The highest amounts of these traits were observed on the planting date of August 1. Means comparison showed that 901475 genotype had the highest tuber weight per plant (811.71 g) and the Agria cultivar had the lowest tuber weight per plant (497.25 g). The maximum plant height, chlorophyll a, b and total chlorophyll content, vitamin C, soluble sugars, and tuber dry matter was related to 8707-26 genotype. On the other hand, 3-7009 and 26-8707 genotype had the highest percentage of starch. Based on these results, it seems that the planting date of August 1 and the foliar application of Freezbon with potassium can enhance the cold tolerance threshold, growth, and performance of potato cultivars in regions exposed to cold stress by regulating physiological and biochemical responses.

The combined use of anti-freezing compounds of frezzebon and potassium improved the morphological and physiological traits of potato genotypes compared to their non-use. Results showed that the simultaneous use of anti-freezing compounds of frezzebon and potassium increased the mean yield of the plant by 24.08% compared to not using them. On the other hand, the planting date of August 1 had a more favorable effect on the studied traits than August 11. So that the mean yield of the plant on the planting date of August 1 was 12.31% more compared to August 11. According to the results, it can be concluded that the application of anti-freezing compounds and the planting date of August 1 caused changes in the morphological and physiological traits of potato genotypes, which provided more suitable conditions for their growth and increase in yield. Therefore, it is possible to recommend the planting date of August 1 and the foliar application of frezzebon with potassium to achieve optimal yield in the potato fields of the Ardabil region.

Cover crops are one of the methods of weed control. For this purpose, a factorial experiment was conducted in the form of a randomized complete block design with three replications in the 2016-2017. Experimental treatments include control (without cover plant), rye (Secale cereale L.), common vetch (Vicia sativa), chickling pea (Lathyrus sativus) and panonica (Vicia panonica) and methods of management of cover crops including used as forage and as cover at the field level. The results of this experiment showed that the highest amount of fresh forage was obtained from rye treatment (6.4 t.ha-1) and the lowest was obtained from common vetch (2.8 t.ha-1). Also, in terms of forage harvest of cover crops, weed density increased by 18% compared to maintaining them in the soil surface. Rye and panonica treatments had 25% and 22% more weed control than other cover crops, respectively. The highest potato tuber yield was obtained from the control treatment. Compared to rye, common vetch, chickling pea and panonica cover crops treatments, 19, 29, 16 and 11% for cover maintenance management and 10, 12, 14 and 11% for cover removal management, respectively, had higher potato yield in the control. Potato yield in weed free treatment was higher compared to cover crops treatments including rye, common vetch, chickling pea and pannica in cover maintenance management 19, 29, 16 and 11% and in cover removal management 10, 12, 14 and 11%, respectively.The results of this experiment showed that although cover crops reduce weed density, their presence at the time of cultivation of the main crop reduces potato yield.

The aim of this study was conducted to investigate the effect of row spacing and cover crops on weed control and yield and components yield of corn (TWC647). This experiment was carried out factorial based on a randomized complete block design with three replications in the farm of Moghan Agriculture and Natural Resources Research Station in 2021. The treatments consisted of row spacing at two levels (75 and 65 cm), cover crops at five levels (rye, hairy vetch, clover, and no cover crop and Maister power herbicide). In the condition without cover crop, the highest total biomass of weeds was obtained at the row spacing of 75 cm. Also, the highest biomass of cover crops in the row spacing of 75 cm was obtained from rye cover crop. The number of grain rows per ear, grain yield, biological yield and harvest index were affected by the interaction row spacing ×cover crop; So that the maximum number of grain rows per ear was observed at a row spacing of 75 cm and clover. The highest biological yield of corn was obtained at the row spacing of 65 cm and rye cover crop. highest grain yield (8.05 tons per hectare) was obtained from the row spacing of 65 cm and the rye cover crop treatment and also the highest control percentage of the total biomass of corn weeds (47.47%) was related to the rye cover crop and row spacing of 65 cm.

Potato (Solanum tuberosum) is one of the most important food products in the world, which is rich in carbohydrates, proteins, vitamins and other nutrients. Choosing the suitable planting date and cultivars is one of the most important and effective ways to reduce the negative effects of environmental stresses on potato characteristics. Cold stress is one of the limiting factors for production of agricultural crops. One of the adverse effects of this stress is increasing the biosynthesis rate of reactive oxygen species that causes oxidative stress. Plants have enzymatic and non-enzymatic mechanisms to overcome oxidative stress. The enzymatic antioxidant defense system includes different enzymes such as superoxide dismutase, catalase, polyphenol oxidase, guaiacol peroxidases and ascorbate peroxidase, and the non-enzymatic antioxidants include the soluble sugars, proline, carotenoids and other compounds such as flavonoids, and polyphenols. Nowadays, application of antifreeze compounds in agriculture is widely used technique to overcome chilling injuries. These substances are quickly absorbed by plants and increase the metabolic activity rate of plants. As a result, the amount of antifreeze proteins, amino acids, carbohydrates, lipids, vitamins and minerals increases in the plant organs leading to more resistance rate of plant cells against freezing. Potassium is one of the elements that reduces the effects of environmental stresses such as drought, salinity, high temperatures, cold, etc. through the accumulation of soluble carbohydrates and osmotic regulation. Also, potassium plays a role in regulating the activity of enzymes related to the detoxification of reactive oxygen species. The aim of the current study was to investigate the influence of cultivar, planting date and foliar application of antifreeze compounds on some of most important morpho-physiological characteristics of potato crop.           

The current study was conducted as a split-factorial experiment based on randomized complete blocks design with three replications at Ardabil Agricultural and Natural Resources Research Station during two cultivation seasons (2018-2019 and 2019-2020). The investigated factors included planting date in two levels (August 1st and 11th), foliar application of antifreeze compound at two levels (foliar application with a mixture of Frezzebon amino acid + potassium, and water as a control) and potato cultivars at 10 levels (901375, 901475, 902375, 8708-7, 8709-106, 7009-3, 905675, 8707-26, Agria and Savalan). Foliar applications were performed at the end of the growth season as same time as the increased likelihood of cold weather (considering the weather forecasts and the measured temperatures in the field and their correlation, one week before the possibility of temperatures below 7 ºC). Furthermore, before the spraying treatments, samples were taken from the experimental treatments and frozen using liquid nitrogen and stored in a freezer. After 24 h of freezing, the samples were again collected from the experimental treatments and rapidly frozen using liquid nitrogen before being transferred to the laboratory for measurement of the desired characteristics. After collecting the samples, laboratory experiments were conducted at the Faculty of Agriculture of Ardabil University of Medical Sciences and the Agricultural and Natural Resources Research Station in Ardabil.

Based on the obtained results, it was found that the foliar application of the amino acid Freezbon combined with potassium increased the yield, number of tuber per plant, leaf relative water content, proline and the activity of antioxidant enzymes. Also, the planting date of August 1st has the highest yield, number of tuber per plant, leaf relative water content, potassium and proline content, and the activity of catalase, superoxide dismutase and polyphenol oxidase enzymes. In terms of yield, 901475 cultivar had the highest yield (43.02 ton ha-1) and Agria cultivar had the lowest yield (26.35 ton ha-1). Among the cultivars studied, 8708-26 cultivar had the highest leaf relative water content, potassium and sodium content. The maximum content of proline and antioxidant enzymes activity were related to 7009-3 and 8707-26 cultivars. Based on these results, it seems that the planting date of August 1st and the foliar application of Freezbon with potassium can enhance the cold tolerance threshold, growth, and performance of potato cultivars in regions with cold weather by regulating physiological and biochemical responses. The results of the current study in line with the observations of the other conducted researches on different horticultural crops demonstrated that choosing appropriate planting date and application of antifreeze compounds positively influence the accumulation rate of osmoprotectants, cells antioxidant capacity and plant water and nutrient status resulting in a significant increase in cold resistance rate of plant cells.

Foliar application of antifreeze compounds Frezzebon amino acid + potassium, and planting date on August 1st can positively influence potato cultivars yield and physiological characteristics under cold conditions, therefore this foliar treatment and planting date are recommendable to overcome negative effects of cold stress on potato characteristics in cultivation reigns with cold weather.

This experiment was carried out in 2018 in the Lundville region of Astara for rice crop rotation, different amounts of nitrogen and potassium fertilizers, and varieties and dates of clover planting in the Gilan region. The experiment was evaluated in the form of s split-split plot with a completely randomized block design in three replications. The main factor includes nitrogen fertilizer with potassium at three levels (50, 100, and 150 kg per hectare) and the spreading of clovers in three different stages of rice growth, including after flowering, before harvest, and after harvest as split plot and secondary factors.

The results obtained from the variance analysis of the data showed that different levels of nitrogen and potassium fertilizers, distribution of clovers in different stages of rice growth, and clover cultivars on the height period, yield indices, and harvest index were significant in rice plants. Based on the results of comparing the average effects of treatments, it was observed that the highest yield of paddy per hectare was obtained under the conditions of application of 100 kg/hectare of fertilizer in the stage of spreading clovers after rice harvesting and from Iranian clover variety.

The use of nitrogen and potassium fertilizers along with crop rotation of rice and clover due to nitrogen stabilization and improvement of the soil substrate increased the height of the plant, increased the number of claws, spike length, the weight of 1000 seeds, and finally increased the yield of the rice plant.

To evaluate the effect of row spacing, planting pattern and density on weed control and morpho physiological characteristics of corn (Zea may L.), the experimental was carried out factorial based on a randomized complete block design with three replications in the farm of Moghan Agriculture and Natural Resources Research Station in 2022. The first factor included row spacing in two levels (75 and 65 cm), the second factor was planting pattern in two levels (single row and zigzag twin row) and the third factor was planting density in two levels (75,000 and 85,000 plants per hectare). The results showed that the highest grain yield and leaf area belonged to the density of 75000 plants per hectare and the row spacing of 75 cm. The highest density and total biomass of weed was observed at density of 75,000 plants per hectare and row spacing of 75 cm, But the lowest density and total biomass of weed was obtained from the density of 85,000 plants per hectare and row spacing of 65 cm. The maximum cob diameter, cob wood diameter and leaf chlorophyll index were obtained at the density of 75,000 plants per hectare with the row spacing of 75 cm and the single row planting pattern. Correlation coefficients between traits showed that the correlation between grain yield with total weed biomass, cob diameter, cob wood diameter, seed depth and leaf chlorophyll index is positive and significant. Generally, the results of this research showed that with extending of twin row patterns with increased density of corn, it is possible to control weed through the competitive ability of the plant, it achieved an acceptable performance.

Drought is one of the most important environmental stresses in the ecosystem of crops. In order to select potato tolerant genotypes to drought stress.

This experiment was conducted in the form of a randomized complete block design with the method of strip chopped blocks in three replications during the two cropping years was performed in Ardabil region. Two levels of non-stress and stress irrigation were compared as vertical factor and 20 potato genotypes were compared as horizontal factor.

The results showed that all measured traits were affected by stress treatments. Under stress treatment, genotype 905675 had the highest tuber yield and tuber weight per plant. The lowest tuber yield and tuber weight per plant were obtained from Marfona cultivar. In addition, with the application of stress, the activity of enzymatic and non-enzymatic antioxidants increased. The highest amount of reducing sugar with 122%, vitamin C with 63%, proline with 106% The percentage of catalase enzyme with 249% increase compared to non-stress conditions was observed in genotype 905675. The highest activity of superoxide dismutase and polyphenol oxidase with 214 and 42% increase belonged to genotype 901375, respectively.

In general, considering the amount of changes in tuber yield, tuber weight per plant, increasing the activity of enzymatic and non-enzymatic antioxidants, genotypes 905675, 901575 and 901375 were selected as tolerant and high yield potential genotypes in both stress and non-stress conditions, respectively, and Milva, Jelly and Marfona cultivars can be introduced as susceptible cultivars.

In order to study different tillage systems, winter cover crops and their effect on improving soil quality and maize weeds, a split-factorial experiment using randomized complete block design was conducted at Agricultural Research and Education Center of Ardebil province (Moghan) during two years to evaluate the effect of winter cover crops, tillage and dosage of MaisTer Herbicide. Two types of tillage system in the main plot conventional tillage and no tillage. The cover treatments including vetch (Vicia villosa L.), Crimson clover (Trifolium incarnatum L), Rye (Secale cereale), barley (Hordeum vulgare L.), Rapeseed (Brassica napus) and no-cover crop, as well as reduced dosage of MaisTer® herbicide were placed in a factorial arrangement subplot. percentage of soil organic matter in the system no tillage was 13.72% higher than conventional tillage. Cover crops reduced the total winter weed density by more than 55% in both years compared to the control without cover crops. Yield of corn in the first and second year were 7.89 and 8.46 tons per hectare, respectively, and this increase in yield in the no-till system was 10.22 percent higher than the conventional tillage system. vetch increased corn yield by 30% more than other plants. Consumption of half dose of Meister regrowth herbicide at 3-4 leaves of corn did not differ statistically from its recommended dose. In general, cultivation of hairy vetch in the fall along with no-till method by applying half the dose of Meister herbicide in corn, can increase soil fertility, reduce corn weed density and production costs.

In order to study of morpho-physiological attributes in corn under influence of weed, an experiment based on randomized complete block design with four replications was performed at the Moghan climate during 2020 growing season.

The experiment was included 14 treatments; seven weed-infested and seven weed free treatments were applied at regular intervals as 0, 10, 20, 30, 40, 50 and 60 days after corn emergence in which weeds were allowed to grow until harvest, and weeds were removed, respectively. Total dry weight of weeds, plant height, length of ear, total biomass, leaf area index (LAI), crop growth rate (CGR), relative growth rate (RGR), net assimilation rate (NAR), leaf area duration (LAD), and yield of corn were measured.

The results showed that all measured traits were affected by weed interference duration and weed control period. Weed interference duration increased total dry weight of weeds and weed-free duration reduced total dry weight of weeds. Also, increase in weeds interference duration significantly reduced, plant height, length of ear, total biomass, LAI CGR, RGR, NAR, LAD, and grain yield of corn. On the other hand, total biomass, LAI, CGR, RGR, NAR, LAD, and grain of corn increased by rising weed-free duration.

The weed interference duration had a significant effect on the final yield of corn and with interference of the all weed season, grain yield of corn decreased. Weed interference duration increased total dry weight of weeds and weed-free duration reduced total dry weight of weeds.

The aim of this study was investigated the effect of weed interference on some growth indices and grain yield of corn (Zea mays L.), an experiment was carried out in a randomized complete block design with four replications during 2019 growing seasons at the Moghan region.

The experiment was included fourteen treatments; seven weed-infested and seven weed free treatments were applied at regular intervals (0, 10, 20, 30, 40, 50 and 60 days) after corn emergence in which weeds were allowed to grow until harvest and weeds were removed, respectively. Total dry weight of weeds, total dry matter (TDM), leaf area index (LAI), crop growth rate (CGR) and yield of corn were measured.

The results showed that all measured traits were affected by weed interference duration and weedcontrol period. Weed interference duration increased total dry weight of weeds and weed-free duration reduced total dry weight of weeds. Also, increase in weeds interference duration significantly reduced TDM, LAI, and CGR and grain yield of corn. On the other hand, TDM, LAI CGR and grain of corn increased by rising weed-free duration.

Considering of 10% yield loss, the critical period of weed control was 3 and 52 days after corn emergence, respectively. The weed interference duration had a significant effect on grain yield of corn and weed interference at the whole season. Weed interference reduced grain yield of corn.

In order to evaluation of dry matter remobilization of assimilates materials amount and their contribution to the yield of different bread wheat varieties and lines in Ardabil, an experiment in randomized complete block design with three replications with ten cultivars (Includes: Uroom, Zare, MV-Magdalena, Soissons, MV-Toborzo, Mihan, Pishgam, FD-11111 and FD-12073) was done in Research Station of Agriculture and Natural Resources of Ardabil in 2015-2016. Analysis of variance showed a significant difference between the lines and cultivars studied, for different traits. FD-11111 line has the highest number of grain per spikes, grain yield per square meter, the share in the filling and grain growth (7417.9 grams per square meter).The MV-bodri variety has the highest biological yield per square meter, the percentage of share the transfer process dry matter from shoot (19.723%) in the yield and maximum transfer of dry matter from total of shoots to the grain. The MV-Magdalena variety also has the lowest biological yield and highest harvest index, the highest percentage (47.797%) of dry matter remobilization efficiency of shoots and with 3.57 percent was the highest current photosynthesis efficiency. The highest current photosynthesis contribution in Zare cultivar (89.923 grams per square meter) that has the lowest proportion of dry matter remobilization was obtained. So generally can be said that was much higher current photosynthesis contribution in increasing grain yield, and FD-11111 line between studied genotypes, was the best lines.

An experiment was conducted to evaluate the effect of different common herbicides on soybean yield and yield components. Experiment was carried out using a randomized complete block design (RCBD) with three replications at the Agricultural and Natural Resources Research Center of Moghan, Ardebil, Iran during 2017-2018. Treatments were the application of ethalfluralin, imazethapyr, trifluralin, metribuzin, bentazone, and alacolor herbicides and with and without hand weeding control. The results of variance analysis showed that the treatments had significant differences in herbicide efficiency, weed density and total dry weight. One month after herbicides spraying, trifluralin and ethalfluralin had the highest effect on the weed control; however, two months after herbicides spraying, all other treatments also showed their control effects and all herbicides were located in same statistical group. In this study, all herbicides treatments significantly reduced the density and dry weight of weeds compared to control; however, their effect was less than hand weeding. The number of pods per plant, biological and grain yield and soybean protein content percentage were significantly affected by all treatments; however, the other traits including plant height, growth period, chlorophyll index, 1000-seed weight, and grain oil percentage were not significantly different. The highest number of pods per plant (333.92) and grain yield (2792 kg/ha) were obtained in hand weeding treatment. Among the herbicides treatments, the application of ethalfluralin had the highest seed yield (1896 kg.ha-1</sup>). Generally, based on the results of this study, application of 2 L.ha-1</sup> ethalfluralin could be recommended for effective weed control in soybean production systems.

Using an effective management method can reduce weed contamination of main crop plants. To investigate the effect of cover crops on weed control and potato yield an experiment was conducted based on randomized complete block design with three replications at Research Field of University of Mohaghegh Ardabili in autumn of 2017 and spring of 2018. Experimental treatments consisted of oat (Avena sativa L.), white radish (Raphanus sativus L.) and double blend cultivation with 50% seed ratio and control treatment at 2017 (autumn) and subsequent potato planting in 2018 (spring). The results showed that the cover crops had a significant effect on lambsquarter (Chenopodium album L.), Amaranthus retroflexus L. and total weeds biomass in the main crop (potato) but not on other weeds (including Cirsium arvense L.). The highest biomass (466.1 g.m-2) among the cover crops and the lowest winter weeds biomass were related to white radish monoculture. The lowest weed biomass of amaranthus and total weeds biomass were obtained from white radish, and the lowest biomass of lambsquarter was obtained from white radish+oat. White radish was able to control 45.7% of total weed biomasses compared to control treatment. The highest yield and average tuber weight, marketable percentage and the lowest small potato tubers were obtained by white radish. White radish had the highest yield (3.74 kg.m-2), which increased potato yield by 46.3%, as compared to the control treatment. The highest number of potato tubers was obtained from oat as cover crop. Growing white radish along with oats also had the highest percentage of oversize tubers. In general, white radish can be a good choice to be used for winter cover crop before potato planting, either as a intercropping with Poaceae species or as a monoculture.

In order to investigate physiological and biochemical changes of wheat under stress residue of Imazethapyr herbicide (Imazethapyr), an experiment was conducted in a completely randomized design with four replications in greenhouse conditions at university of Mohaghegh Ardebili. The treatments consisted of five dose levels of herbicide Imazethapyr (0, 0.011, 0.022, 0.033 and 0.044 micrograms of herbicide) per kilogram of soil. The analysis of variance showed that the content of the main and auxiliary pigments of leaf, proline, sugar content, protein, activity of catalase enzymes, peroxidase, polyphenol oxidase, root and shoot dry weight were significantly affected by herbicide. The results showed the Imazethapyr herbicide stopped the production of valine leucine and isoleucine amino acids. As a result, the rapid reduction in the volume of these amino acids led to a reduction in protein synthesis in wheat plant. Therefore, the application of doses of 0.011, 0.022, 0.033 and 0.044 micrograms of herbicides decreased 14, 26, 44 and 47 percent of leaf protein content, respectively, compared with control treatment. Further, theapplication of these doses resulted in the reduction of 2.8, 5, 27 and 64% of activity of catalase enzyme, 3.5, 39, 49 and 52% peroxidase enzyme activity and 13, 24, 35 and 46% activity of polyphenol oxidase enzyme, compared with control treatment. The results revealed that Imazethapyr herbicide activates wheat antioxidant enzymes to reduce plant tolerance from damage caused by herbicide residues; therefore, it can be used as a marker or index of herbicide damage rate in physiological research.

In order to investigate the effect of weed control with common herbicides on yield and components of soybean yield (Glycin max L.) in the second crop, two experiments were conducted as a randomized complete block design with three replications at the Agricultural and Natural Resources Research Center of Moghan during 2016-2017 and 2017-2018. The treatments consisted of Ethalfluralin, Imazethapyr, Trifluralin, Metribuzin, Bentazone and Alacolor herbicides with and without weed control. The results showed that the number of pods per plant, biological yield, grain yield and soybean protein percentage were statistically significant, but for chlorophyll index, 1000 seed weight and oil percent grain, the difference was not statistically significant. The highest number of pods per plant (333.92), biological yield (1221 g.plant-1) and grain yield (2792 kg.ha-1) were obtained from hand weeding. The results of the analysis of variance showed that the treatments had a significant difference in terms of the percentage of the effect of herbicide, density and total weed dry weight. The results showed that one month after spraying, the Trifluralin and Ethalfluralin herbicides had the highest effect on the weed control and two months after spraying, the rest of the treatments also showed their effect and all herbicide treatments were in one group. In this study, all weed control treatments significantly reduced the density and dry weight of weeds than without control, but their effect was less than hand weeding. The highest grain yield (1896 kg.ha-1) and the highest biological yield (784.9 kg.ha-1) were observed from Ethalfluralin herbicide

Eight sesame genotypes along with Oltan and Darab1 cultivars were evaluated for seed yield and oil biochemical traits using randomized complete block design with there replications under normal and drought stress conditions in Karaj, Iran, in 2014 and 2015. Drought reduced seed yield by 45.1 %, oil content by 2.5%, palmitoleic fatty acid by 24.0%, and increased the antioxidant power of oil by 99.4%, total lignin of oil by 18.9 and seed crude protein by 15.6%. In fact, drought stress had a beneficial effect on seed oil quality. Genotype KC50662 had reasonable yield under two conditions. In addition, its seed oil content was 5.3% higher than cv. Oltan. This genotype had the lowest amount of harmful palmitic fatty acid (8.5%) second next to Oltan cultivar (8.2%). This genotype had more beneficial oleic (47.1%) and palmitoleic (0.09%) fatty acids compared to cv. Oltan (43.1% and 0.07%, respectively). This genotype also had lower level of stearic acid (4.7%), higher level of linoleic acid (42.0%), higher level of lignans (4237 mg kg-1), and lower level of antioxidants power (23.5 µmol L-1) compared to cv. Oltan (5.4%, 38.7%, 3541mg kg-1, and 33.9 µmol L-1, respectively). Tolerance and susceptibility indices could identify genotype KC 50662 as high yielding, and KC 50658, KC 50687 and KC 50983 as tolerant genotypes. In conclusion, genotype KC50662 was identified as superior genotype with high seed yield, in both normal and stress conditions, and oil quality properties.

The use of cover crops before planting the main plant along with selecting the type of tillage can be considered as one of the effective methods in sustainable agriculture. In order to show the efficacy of this system, an experiment was conducted in a no-tillage system and with six treatments, barely (Hordeum vulgare L.), rye (Secale cereal L.), rape (Brassica napus L.), vetch (Vicia villosa L.), crimson clover (Trifolium incarnatum L.) and control, in a randomized complete block design with three replications, at the farms of agriculture and education research center and natural resources of Ardabil Province (Moghan) during the 2015-2017. Variance analysis showed that the effect of the treatments on the total weed density was significant. On average, in four sampling stages, total control of winter and spring weed at barley, rye, rape, vetch and clover treatments were 83.5,77.25,66,25,51, and 26.25 respectively. The results also showed that the soil cover percentage was significantly

In order to identify the effect of water stress on potato traditional cultivars and advanced clone growth this experiment was carried out under field conditions as Split-plot design based on Randomized Complete Block Design with three replications in Ardabil Agriculture and Natural Resources Research Station during 2015. Main plots included three irrigation levels: complete irrigation, mild and severe water stress and sub-plots included 5 potato cultivars: Agria, Spirit, Marfona, Luca, Hermes and 397008-9 promising clone. Results showed that in spite of the effect of water stress on marketable tuber number per plant, other studied traits such as tuber weight per plant, marketable tuber weight per plant, total tuber yield and marketable tuber yield were influenced by irrigation and cultivar treatments. Luca and Marfona produced the highest marketable tuber weight per plant and marketable tuber number per plant, respectively and also the 397008-9 promising clone had the most highest total tuber yield and tuber weight per plant due to genetic diversity. There were no significant interaction effect between cultivars × irrigation levels on any traits. Because of no significant difference between complete irrigation and mild water stress treatments and also economic importance of tuber yield for farmers, It seems that replacement of complete irrigation by mild water stress, not only will lead to relative maintaining water resources, but also will produce good marketable tuber yield (In accordance with the cultivar).

Today, cover crops are an effective tool in non-chemical weed management in sustainable agriculture (Ateh and Doll, 1996). This experiment was conducted to investigate the effect of cover crops on weed management and the yield of peppermint (Mentha piperita). In order to evaluate the effect of cover crops on weed management and yield of peppermint (Mentha piperita), a factorial experiment was conducted with a randomized complete block design with three replications at the Agricultural Research Field of the University of Mohaghegh Ardabili, Iran, in 2012. The first factor included: spring wheat, spring barley, winter rye, winter wheat, winter barley, mixed winter rye + winter barley. Cover crop management methods included: undercutting mulch, heading living mulch, and cover crops killed with herbicide as a second factor. Two controls were also included in the experiments: no cover crop with weeding and no cover crop without weeding. To investigate the effect of cover crops on density and weed biomass, three stages of weed sampling were performed, 30, 60, and 90 days after the peppermint (Mentha piperita) planting (except for weed control plots and no weeding) in a plot of 0.5 × 0.5 square meters. Also recorded were number of branches, stem length, leaf fresh weight, leaf dry weight, and fresh yield. The results showed that the main effect of the cover crop was significant on the number of branches and the main effect of cover crop management had a significant effect on peppermint properties and the dry weight and density of weeds. Most of the trait impact was positive in all the methods of cover crop management of weed control. The results showed that peppermint traits were most affected with undercutting management and heading living mulch. The second most effective was cover crops killed with herbicide. Comparison of interaction effects showed that by using heading living mulch winter wheat, undercut spring barley and winter rye had the highest fresh yield. The main effect of cover crop type on the first sampling on dry weight of redroot pigweed (Amaranthus retroflexus L.) was significant for weed density of bindweed (Convolvulus arvensis L.) in the third sampling and the cover crop management for all weeds in all three samplings. On average in the three stages of sampling, the dry weight and density of the control weed of redroot pigweed, common lambsquarters (Chenopodium album) and bindweed in undercutting mulch, heading living mulch, killed cover crops with herbicide were 66%, 73%, 38% and 59%, 70% and 44%, respectively. The results of this study showed that cover crops are effective strategies for weed control. In this experiment, cereal crop plants with rapid growth and high biomass, reduced the density and dry weight of annual and perennial weeds (Blanco-Canqui et al., 2013 Jahanzad et al., 2013 Jahanzad et al., 2014) and had a good effect on the fresh leaf yield of peppermint. In general, to achieve more effective control of weeds and healthy production, the treatment of heading living mulch winter wheat was appropriate.

Maize is one of the important cereal crops in Iran. Moghan, in Ardabil province, is an appropriate region to grow it in the country. Redroot pigweed (Amaranthus retroflexus L.) is one of the major noxious weed in maize fields worldwide and also in Iran. To study the interference of effect of this weed on maize seed yield and its morphological characteristics, a factorial experiment based on randomized complete block design with three replications was carried out at the research field of Agricultural and Natural Resources Research Center of Ardabil (Moghan) in 2012. The experimental factors were maize plant densities with four levels (70000, 75000, 80000 and 85000 plant.ha-1) and redroot pigweed densities with four levels (0, 4, 8 and 12 plant/m per row). The results showed that increasing density of maize and redroot pigweed, grain yield, biological yield and chlorophyll content of maize leaves were significantly reduced. The highest grain yield (11.88 t.ha-1) at density corn of 80000 plants.ha-1 of maize under weed free condition and lowest grain yield (7.92 t.ha-1) at maize density of 75000 plants.ha-1 with the presence of the 12 plant/m per row of redroot pigweed. The highest biomass of redroot pigweed (497.8 g/m per row) was produced at density of 85000 plants.ha-1 of maize with the presence of the 12 plant/m per row of redroot pigweed. Generally, the results of this research showed that 80000 plants.ha-1 of maize resulted in highest control of redroot pigweed and grain yield.

The use of cover crops can be considered as an effective method in sustainable agriculture through reducing herbicide use, improving soil and increasing crop yield. An experiment was conducted using randomized complete block design with three replications in Agricultural and natural resources research center of Ardabil (Moghan) in 2015-2016. Cover crops was considered as the main factor (mixed wheat + crimson clover, monoculture wheat and mixed (rye + wheat)) and mulch management as subplots and control (no cover crop use post-emergence herbicide Maister (Foramsulfuron + Idosulfuron 3.1% OD)). The results showed no significant difference between treatments in terms biomass production, the lowest weed biomass was related mixed of rye + wheat in both crop management methods. In wheat and wheat+ rye a significant decrease was observed in crop yield components possibly due to the release of allelopathic materials and soil properties, But the crimson clover mix of wheat + maize yield satisfactory beside weed control a good yield was obtained after the treatment with herbicide. The results showed that the effect of cover crop, crop management and their interaction except grain weight, were significant for ear dry weight, biological yield, number of rows per ear and number of kernels per ear. The highest values of grain yield, ear dry weight, biological yield, number of grains per ear was achieved in treatments clover + wheat and the least amount of yield and yield components of treated wheat was obtained in residues removed management.