m.h. rashed mohassel

In conventional formulations such as emulsifiable concentrates (EC), wettable powders, soluble liquids, etc., complete availability of the active agent is usually considered immediate or rapid following usage. Application rates of these formulations of pesticides are greater than the minimum threshold concentration to counter losses from sorption, volatilization, photodecomposition, microbial and chemical degradation, and leaching. Controlled-release technology for pesticides could reduce environmental damage and increase efficiency by enhancement of delivery to the site of action. This survey was conducted to determine the possibility of EPTC and trifluralin efficiency improvement by using microencapsulated formulation (MC) that were first synthesized in Iran.

Two separated greenhouse experiments were conducted in Tirtash Research and Education Center (Mazandaran–Iran) in 2014. The experiments were carried out in a factorial arrangement based on a randomized complete block design with three replications. The Microencapsulated formulation of EPTC and trifluralin herbicides were compared with emulsifiable concentrate formulation (Eradicane 82% and Treflan 48%) in 0 (control), 25, 50, 75 and 100 percent of active ingredient (a.i.) (4.92 and 1.2 kg a.i./ha, recommended doses for EPTC and trifluralin, respectively). For this purpose, the soil of pots were infested with the seed of Green foxtail (Setaria viridis) and Redroot pigweed (Amaranthus retroflaxus). The responses of weeds to treatments, specifically seedling number, were analyzed using ANOVA tests, non-linear regression, and fitting to three parameters of Weibull and log-logistic equations. This analysis was based on Akaike's Information Criterion, Residual Standard Error, and Lack-of-Fit Test indices in the R3.4.1 program. The effective dose were determined for 10, 50 and 90 percent of weed control (ED10, ED50 and ED90, respectively). Relative potency index (R) of formulation types were determined by divided ED50 of EC into MC formulations.

According to the results of the experiments, the formulation type had a significant effect on the weed numbers. The MC formulations of EPTC increased Green foxtail and Redroot pigweed control efficiencies. The ED10, ED50 and ED90 decreased from 0.72, 2.94 and 7.18 kg a.i.ha-1 in the EC to 0.41, 1.87 and 4.89 kg a.i.ha-1 in the MC formulation for Green foxtail and 1.08, 3.29 and 10.02 kg a.i.ha-1 in the EC to 0.57, 2.36 and 9.67 kg a.i.ha-1 in the MC formulation for Redroot pigweed. The R index of EPTC in Green foxtail and Redroot pigweed control were 1.57 and 1.39, respectively. Weed control increased as trifluralin dosage increased in both of the formulation types, although in higher doses of the MC, weed control efficiency increased more than the EC formulation. So the efficiency of the MC formulations depended on application dosages. The ED10, ED50 and ED90 of Green foxtail were 0.14, 0.55 and 1.27 kg a.i.ha-1 in the EC and 0.19, 0.52 and 0.98 kg a.i.ha-1 in the MC formulation. The ED10, ED50 and ED90 of Redroot pigweed were 0.20, 0.64 and 2.02 kg a.i.ha-1 in the EC and 0.26, 0.56 and 1.19 kg a.i.ha-1 in the MC formulation. So that the R index of trifluralin in Green foxtail and Redroot pigweed control were 1.05 and 1.14, respectively. The dependency of trifluralin behavior to applied microcapsule dose may be connected to capture of herbicide in microcapsule particles which it causes reduction of bioavailability of herbicide in soil lower than the threshold doses of injury level. Whiles under this experimental conditions, the herbicides are less affected by degrading agents and therefore have less opportunity to express the advantages of MC formulation. Whereas the field studies results showed that the 50% of the recommended dosage of MC formulation had same efficiency as 75% of the recommended dosage of EC formulations (results were not published).

Microencapsulation is a versatile tool for product design and is successfully used in various sectors and for a variety of different product features. However, although lot of research has been performed, only relatively few developments have made it into products in the agrochemical area. For example 37 actives out of 908 listed in total in the pesticide manual, mainly insecticides, are described as being formulated as control solutions. While the development of this technology in agriculture can play an important role in preserving the environment and reducing the pollution caused by pesticides. The purpose of the application of controlled release formulations is the gradual release of herbicides in a suitable amount with maintaining efficiency in agronomic conditions. This type of formulation is a combination of the herbicide and associated material that releases effective material over a given period due to weed control. The results of this study showed that the R index of EPTC and trifluralin were 1.57 and 1.05 in Green foxtail, and 1.39 and 1.14 in Redroot pigweed control, respectively. So that the microcapsule formulation of EPTC and trifluralin herbicides increased the efficacy and reduced the application dose.

The effectiveness of herbicides is influenced not only by the active ingredients and their toxicity but also by the formulation of the herbicide. Conventional herbicide formulations include wettable powder and emulsifiable concentrate (EC). EC formulations are prepared by mixing the active ingredient with solvents and surfactants. However, these formulations can have negative phytotoxic effects due to hazardous solvents and can be unsafe for operators during application. As an alternative to EC formulations, capsule suspension (CS) formulation has been considered. EPTC is a thiocarbamate herbicide used to control the growth of germinating annual weeds, including broadleaves, grasses, and sedges, in crops such as tobacco in Iran. EPTC acts by inhibiting cuticle formation during the early stages of seedling growth. It is available in formulated products such as emulsifiable concentrate (EC) liquids containing up to 87.8% active ingredient and granular (G) formulations containing up to 25% active ingredient. However, there have been few studies on the production of microcapsule formulations of this herbicide. This experiment aimed to evaluate the weed control effectiveness of EPTC microcapsule formulation, which was synthesized for the first time in Iran. Additionally, the study examined the effect of the herbicide extender, Ammonium thiosulfate, at different doses and application methods.

To investigate the effectiveness of different herbicide formulations and application methods, a three-way factorial experiment was conducted in Tirtash Research and Education Center in Mazandaran province, Iran, during the 2014 growing season. The experiment followed a randomized complete design (CRD) with three replications.
The factors studied in the experiment were:
Herbicide formulation:
Emulsifiable concentrate formulation (Eradicane® EC 82%)
Emulsifiable concentrate formulation with Ammonium thiosulfate
Microcapsule formulation
Herbicide dose:
50% of the recommended active ingredient (2.46 kg a.i. ha-1)
75% of the recommended active ingredient (3.69 kg a.i. ha-1)
100% of the recommended active ingredient (4.92 kg a.i. ha-1)
Herbicide application method

Soil-incorporated pre-planting
Pre-planting
A control plot with no herbicide application was also included. Throughout the growing season, weed density, weed dry weight, and tobacco yield were measured. The relative weed control compared to the control treatment was used to evaluate the efficiency of the different treatments. The collected data was subjected to analysis of variance using Minitab (Version 18), and mean comparisons were performed using the honestly significant difference (HSD) test at a significance level of 0.05.

Based on the relative frequency of weeds, Setaria viridis L. and Amaranthus retroflexus L. were dominant species. The experimental results show the effects of formulation type, application dose and method of application on weed density and weed dry weight and tobacco yield were statistically significant difference. The microcapsule formulation increased weed control efficiency and tobacco yield significantly compared to EC formulation and the highest weed control performance and tobacco yield belong to the soil incorporated of microcapsule formulation with recommended dose.

The results indicated that the utilization of a microcapsule formulation allows for a 25% reduction in the application dose of the EPTC herbicide, without compromising weed control or tobacco yield. Consequently, there were no significant differences observed between applying 75% of the recommended dose using the microcapsule formulation and applying 100% of the recommended dose using the EC formulation, with or without the extender. Based on these findings, it is crucial to promptly mix the herbicide with the soil immediately after spraying in order to maintain the efficiency of EPTC. Furthermore, it was discovered that employing two-thirds of the recommended dose of the microcapsule formulation yields the same level of effectiveness as the recommended dose of other formulations. Additionally, incorporating the EPTC herbicide with soil in all formulations enhanced weed control efficacy. In contrast to previous research suggesting the positive impact of extender adjuvants such as ammonium thiosulfate on herbicide efficiency, this study did not observe similar effects. This discrepancy may be attributed to the varying soil and climatic conditions at the test site.

 Water is the most frequently used carrier for herbicide applications. Thus, the physicochemical properties of water in spray mixture can affect the activity of herbicides. A high concentration of Na+, K+, Ca2+, Mg2+, Fe3+ and other cations in hard water can decrease herbicide efficacy. Weak acid herbicides that have been antagonized by one or more of the above cations include sethoxydim, 2,4-D, 2,4-DB, clethodim, imazethapyr, tralkoxydim, and glufosinate and glyphosate. Approaches to minimize hard water antagonism have included decreasing the spray carrier volume and using water-conditioning additives that have proven effective at ameliorating cation-caused antagonism include ammonium sulfate, ammonium nitrate, potassium phosphate, and citric acid. Passing hard water containing Ca2+, Mg2+ or Na+ through an external magnetic device results in the nucleation and crystallization of the respective carbonates. As a result, hard water can be softened for a period. Considering that the hardness of Iranian agriculture is increasing and adding an adjuvant to spray solution is also considered to be more environmental contamination, therefore, the physical conversion of hard water to soft water via its passage through a magnetic field is definitely a good alternative. The objectives of this research were to investigate the effect of adding CaCO3, MgCO3, Na2CO3, K2CO3, or Fe2(CO3)3 to distilled water on glyphosate efficacy to jimsonweed (Datura stramonium L.), and to compare the chemical hard water softening methods (ammonium sulfate, ammonium nitrate, citric acid and potassium phosphate) to a new physical hard water softening method (passing carrier through a magnetic field) to Reduce the incompatibility of hard water cations with glyphosate.

 The seeds of jimsonweed were collected from plants in the fields of Qazvin city, Iran. They were stored in the dark at room temperature until use. Bioassays were conducted in a greenhouse located on the Ferdowsi University of Mashhad, Iran. To increase seed germination before starting the experiment, the seeds were washed every 1 hour for 7 days to remove seed germination inhibitors. Twenty-five seeds were sown at 0.5 cm depth in 2 L plastic pots filled with a mixture of sand, clay loam soil, and peat (1:1:1 by volume). At cotyledon-leaf stage, the seedlings were thinned to four per pot. The pots were irrigated every four days with tap water. Treatments were sprayed at the four-leaf stage. The experiment was arranged as a completely randomized design with four replications as a factorial design with factors of carrier type (distilled water alone or containing 0.5 g L-1 of CaCO3, MgCO3, Na2CO3, K2CO3, or Fe2(CO3)3) and hard water softening method (ammonium sulfate, ammonium nitrate, potassium phosphate, citric acid, and passing through a magnetic field) and glyphosate dose (0, 12.81, 25.62, 51.25, 102.5 and 205 g a.i. ha-1). For magnetizing the carriers, it was passed 10 times through a magnetic treatment device modified from Rashed-Mohassel (30). The mixing order for treatment solutions was (i) adding CaCO3, MgCO3, Na2CO3, K2CO3, or Fe2(CO3)3 to distilled water, then (ii) adding/using water conditioning method, and after 15 min (iii) adding glyphosate. Then, the solutions were sprayed after about 5 min using a calibrated moving boom sprayer at 180 L ha-1 at 200 kPa with 11002 flat-fan nozzle. Shoots were harvested four weeks after treatment, dried for 48 h at 70°C, and dry weight was determined. The data of shoot dry weight were subjected to a non-linear regression analysis for determination of ED50 values (herbicide dose needed to obtain 50% reduction in dry weight) using the following logarithmic logistic dose-response model. The relative potency (R), the horizontal displacement between the two curves, was also calculated.

 As judged by the relative potency values given in Table 1, the hard water softening methods decreased the ED50 values when distilled water was used as the carrier. Therefore, the activity of glyphosate against jimsonweed was significantly increased in the presence of the hard water softening methods. There were significant differences in performance among hard water softening methods as ammonium sulfate was the most effective method. Glyphosate activity was not decreased when applied in a K2CO3 solution but it was decreased when applied in Na2CO3, MgCO3, CaCO3 or Fe2(CO3)3 solutions. Except potassium phosphate which had only a significant effect at reducing the antagonism in the CaCO3 carrier; all hard water softening methods could restore glyphosate activity in hard water contaminated carriers to efficacy levels comparable to glyphosate alone in distilled water. There was no statistical difference in response between the magnetized carrier and ammonium sulfate when they were used in Na2CO3, MgCO3, or Fe2(CO3)3 solutions. It is reported that hard water softening methods may adjust the spray solution pH so that more active ingredient can transport across the leaf surface into the plant via ion trapping phenomenon. Ammonium sulfate was the most successful method to ameliorate the decreased glyphosate activity due to antagonism with Na+, Mg2+, Ca2+, or Fe3+ in the spray solution. By adding ammonium sulfate, the sulfate ion () conjugates with the hard water cations and removes free cations from solution by forming cation-SO4 molecule, allowing ammonium ion () to form glyphosate-NH4 molecule. A glyphosate-NH4 molecule diffuses across the cuticle easier and quicker. A mechanism for physical hard water softening method is illustrated in Fig. 2.

 Although the physical hard water softening method was not effective as compared to some chemical hard water softening methods (ammonium sulfate and citric acid), from the point of view of economical and agricultural, applying the physical hard water softening method will be benefit because it needs no chemical.

Cropping history can affect our knowledge about the compositions and diversity of weed communities in the soil. Weed Species composition and density are influenced by farming practices and vary from field to field and among areas within fields. Plants that escape control and produce seeds within the field can be considered as a major source of seed entering the soil. Crop rotation is an effective weed management tool which can change weed distribution pattern by increasing selection pressures. Two types of rotation including corn-winter wheat and fallow-winter wheat are the most common cropping systems in arid and semi-arid areas of Iran. The multiple tillage operations can affect the vertical distribution, germination and emergence of weed seeds in the soil. Weed seed bank density, species composition and diversity will change when crop management practices are altered.

A field experiment was conducted to evaluate the effects of corn-wheat and fallow-wheat crop rotations on weed seed bank dynamics and seedling population during 2016-2018 growing season at Shiraz University. The fields divided into 10 by 10 meter grids. Soil samples were taken from 0-15 and 15-30 cm depths by soil sampler (auger) with 10 cm diameter. These samples collected after seedbed preparation and before crop sowing from 144 points. The samples of each depth were mixed together, placed in black plastic bags, and transferred to the laboratory. Then, 250g of the total soil was weighed and separated. These samples was placed in silk bags and washed with low water pressure. Finally, weed seeds dried, identified and counted to the level of species using a binocular stereomicroscope. Those seeds that were resistant to forceps pressure assumed as healthy seeds. Weed seedling population were calculated using a quadrat before and after application of herbicide at the same points were seed bank was carried out. Geostatistics technique was used to investigate density and spatial distribution of weed seedlings in two different crop rotations.

The highest frequency of weed seed bank belongs to Portalaca oleracea, Amaranthus retroflexus, Chenopodium album and Lamium amplexicaule. Relative density of P. oleracea and A. retroflexus seeds increased in corn-wheat rotation compared with fallow-wheat. The results showed that weed seed frequency was significantly affected by crop rotation and depth of plowing. As corn-wheat rotation had 33% increasing and fallow-wheat 19.44% decreasing of weed seed in 15-30 cm soil depth. The size of the total weed seed bank in corn-wheat caused a greater seed accumulation in the surface layer of the soil (0-15 cm). Weed seed density in corn-wheat rotation increased 89.79% and 62.85% in 0-15 and 15-30 cm, respectively during two years. Shannon diversity index increased by 12% in corn-wheat and decreased by 5.4% in fallow-wheat compared with the first year. Margalf index of corn-wheat rotation at 0-15 and 15-30 cm of soil depths decreased 33.70% and 38.25%, respectively, compared to the fallow-wheat rotation in the first year. Sorenson similarity index of corn-wheat and fallow-wheat at 0-15 and 15-30 soil depths was 0.82% and 0.80% during two years. The slope of linear regression also indicates that fallow-wheat weed seed bank (0.79) decreased more than corn-wheat rotation (0.47). Spatial distribution of weed seedlings showed that there is a large similarity in distribution patterns of total weed population between before and after herbicide application in two different rotations during the second year. However, distribution pattern of seedlings in corn-wheat rotation at the first year herbicide application was different after application of herbicide. Therefore, herbicide application can affect spatial distribution and number of weed seedling species.

Corn-wheat rotation as a high input level cropping system with deep tillage increases the size of the weed seed bank, especially in the soil surface layer (0-15 cm). While fallow-wheat rotation as a low input level cropping system causes a decreasing in weed seed bank dynamics, increasing in the diversity and richness of the seed bank and improving the soil structure by wheat residual on the soil during fallow system. The results of this study will be valuable in aiding the prediction of likely weed infestations in rotation systems. This ability to predict the size of weed seed bank, pouplation, diversity and emergence would also provide valuable input to population dynamics models that can be used in weed management.

Knowledge of weed biology helps to optimize weed management strategies and avoid unnecessary weed control input by for example accurate prediction of emergence timing of the weeds. According to the available references, 200 species of dodder have been reported in the world of which 18 species are in Iran. Among the 18 reported species in Iran, Cuscuta campestris and Cuscuta monogyna cause the greatest damage to crops and horticultural products in Iran. Cuscuta monogyna (Vahl), a member of the Cuscutaceae family, is a non-specific aboveground holoparasite, and as such is totally dependent on its host plant for assimilates, nutrients and water supply. Eastern dodder is one of the important dodder species that parasite fruit trees and ornamental shrubs. Each eastern dodder plant produces greater than 3000 seeds of which low percentage germinate in the first year. In the field, dodder started to germinate in March or April when daily average soil temperatures reached 10°C, and maximum germination was observed in May or June when daily average soil temperatures reached 20°C. After germination, seedlings of Cuscuta spp. Undergo a non-parasitic phase of growth, dependent on seed reserves, for 2–3 weeks. To improve management systems for specific weed species, it is critical to have good information on seed dormancy, persistence, production, seasonal germination, seedling emergence, and variations among populations. The objective of the present study was to effect of temperature and salinity on two eastern dodder (Cuscuta monogyna Vahl) ecotypes seed germination characteristics.

In order to study the effect of salinity and temperatures on seed germination chrachteristics of two eastern dodder ecotypes experiments were conducted based on factorial in a completely randomized design with three replications in the Research Laboratory of Ferdowsi University of Mashhad Faculty of Agriculture during 2015 and 2016. Treatments include salinity stress in 8 levels (0 (Control), -0.1, -0.2, -0.4, -0.6, -0.8, -1 and -1.2 Mpa) and temperature at 8 levels (5, 10, 15, 20, 25, 30, 35 and 40oC). After 14 days, seeds in treatment solutions were no longer germinating, so all germinated seedlings were removed and un-germinated seeds of the highest salinity treatment (-1.2 Mpa NaCl) were rinsed with distilled water and placed back in their dishes with 5 mL of distilled water for 14 more days.

Results showed that with increasing salinity at each level of temperature germination rate and percentage reduced in both ecotypes, so that in potential -1.2 Mpa germination was stopped in both ecotypes. In both ecotypes germination stamped at 5, 10 and 40 ̊C temperatures in all levels of salinity. In both ecotypes the highest percentage and rate of germination were indicated at control treatment salinity and 25 and 30 ̊C temperatures. It is believed that the effect of high concentration of NaCl at high temperatures can be attributed to the toxic sodium that causes irreversible damage. According to the results Bardaskan ecotype was better than Qouchan ecotype in view of germination at high levels of temperatures and salinity treatments. The three parameter logistic model provided a satisfactory fit for the response of seed germination to NaCl concentration. The effective salinity for reducing of 50% seed germination in Qouchan ecotype at 15, 20, 25, 30 and 35 ̊C temperatures were -0.79, -0.86, -0.87, -0.77 and -0.68 Mpa and in Bardaskan ecotype were -0.93, -0.93, -0.95, -0.90 and -0.75 Mpa respectively. Recovering the ungerminated seeds from the salinity level of -1.2 Mpa and reincubating them with distilled water resulted in a germination of 70% in both ecotypes, indicating that enforced seed dormancy was mainly because of an osmotic effect, as opposed to toxicity owing to an ionic effect.

This study shows that eastern dodder has capacity to survive and reproduce even under a higher temperature and higher degree of salinity stress. The information of this study would be helpful for estimating the potential of this species to spread to new areas and for the improvement of this parasitic weed species management programs. As is evident from these experiments, the effective, long-term reduction of eastern dodder populations will require the use of an integrated weed management approach.

Sethoxydim is a post emergence graminicidethatcontrolannual and perennial grasses such as wild oat (Avena ludoviciana Durieu.) and littleseed canarygrass (Phalaris minor Retz.) by inhibitory activity on acetyl coenzyme A carboxylase enzyme and disrupt fatty acid biosynthesis. It belongs to the cyclohexanone chemical family. It was registered for weed management in broad leaf crops. Using an adjuvant (e.g. vegetable oils and surfactants) that can increase the foliar activity of post emergence herbicides by cuticle destruction and increase leaf wetting is an acceptable way to achieve this approach. Applying vegetable oils increased graminicide penetrate to leaf and post emergence herbicides performance. Some synthetic adjuvants have been shown a side effect on wildlife, similar to agrochemicals therefore using safe and reproducible adjuvants is essential. The objective of this research is to determine the best vegetable oil on biological activity of sethoxydim on wild oat and relation between compounds of vegetable oils (fatty acids) and their effects on sethoxydim performance.

The dose response experiment was conducted in Research Greenhouse of Ferdowsi University of Mashhad in 2012. The seeds of wild oat were collected from plants in the fields of the Mashhad Agricultural and Natural Resources Research Center, in Mashhad, Iran and preserved at room temperature in paper bag. The seeds were surface sterilized by immersing in sodium hypochlorite for 5 minutes. Then seeds were rinsed by distilled water for 15 minutes. To increase seed germination before the start of experiment, the seeds were dehulled and placed in Petri dishes on top of a single layer of Whatman no. 1 filter paper. Then, 10 mL of 0.2% KNO3 solution were added to each Petri dish for breaking dormancy, then the seeds were incubated for 72 h at 4–5◦C in the dark. The germinated seeds were sown in pot (1.5 L). One week after sowing plants were tinned to four plant in each pot. The pots were irrigated every days. At four leaf stage of wild oat plants the herbicide treatment were applied. The treatments included sethoxydim concentration at seven levels (0, 23.4, 46.8, 93.75, 187.5, 281.25 and 375 g ai ha-1 of sethoxydim) and vegetable oils at ten levels (without oil and with turnip, olive, soybean, corn, sunflower, canola, sesame, castor, and cotton oil). The response of wild oat biomass were analyzed by non-linear regression by R software. To determine toxicity of sethoxydim plus vegetable oils on sugar beet and onion an experiment by recommended dose of sethoxydim was conducted. Moreover, an experiment was carried out to determine the fatty acid content and quantity of each vegetable oil. To determine the chemical nature of fatty acid oils, 15 drops of each vegetable oil were added to 7 mL N-hexane plus 2 mL of potassium hydroxide in methanol (11.2% m/v). Then, four replications of the supplied compounds were shacked for 1 min and heated to 55°C for 5 min until the solution was separated into two phases. The upper phase was desiccated with sodium lauryl sulfate and filtered to analyze with gas chromatography. The fatty acid content was determined using gas chromatography Acme 6000 (Younglin, South Korea) equipped with a flame ionization detector and a CP-Sil 88 Wcot fused silica column (100 m × 0.25 mm i.d. × 0.2 μm film thickness; Chrompack, Middleburg, Netherlands). The carrier gas was ultrahigh-purity helium; we used a 1:100 split mode and a flame-ionization detector. The GC oven temperature was maintained at 140 °C for 5 min, then ramped to 240°C at the rate of 4°C/min and maintained at 240°C for 15 min. The flow rate of helium was 20 mL/min. The injector and detector temperatures were 250 and 280°C, respectively. The volume of injected sample was 1 μL. Fatty acids were identified by matching their retention times with those of their relative standards.

Results of this study showed that sethoxydim performance improved in the presence of vegetable oils whereas relative potency were higher than 1 in the presence of vegetable oils compared to sethoxydim alone. The vegetable oil could be ranked based on their relative potency value as: turnip > olive > soybean > corn > sunflower > canola > sesame > castor > cotton. The overall results showed that the efficacy of sethoxydim was improved by increasing the content of unsaturated fatty acids in vegetable oils. Turnip and cottonseed oils with 71.17 and 20.65 percentages of unsaturated fatty acids had the highest and lowest performance, respectively. Among the polyunsaturated fatty acids compounds, linoleic acid content had a key role in the efficiency. There was a negative relationship between linoleic acid content and the performance of vegetable oils. Moreover, non-significant toxicity effects on sugar beet and onion was observed.
   

Based on this work, when the vegetable oils used the performance of sethoxydim on wild oat control based on relative potency were improved. Therefore, synthetic adjuvants can be replaced by vegetable oils as adjuvants in herbicide application. Based on results of this work, composition of fatty acids in vegetable oil is a very effective factors for increasing sethoxydim performance on wild oat control. By increasing unsaturated fatty acids, the sethoxydim performance showed more performance whereas turnip oil with higher unsaturated fatty acids was showed the highest performance. Further research is needed to determine the mechanism of action of vegetable oils in increasing the effectiveness of herbicides.

Supplies of irrigation water are severely limited and water use efficiency (WUE) has become more vital, especially for valuable drought tolerant plants. Green cumin (Cuminum cyminum L.) is a medicinal and spices plant adapted to arid and semi-arid regions such as Iran. Planting date, irrigation and plant density can affect quality and quantity of cumin. Seed yield of cumin decreases by increasing water deficit, despite absorbing water even in very low water potentials. Changes in planting date can also affect water use efficiency due to rainfall and evapotranspiration (ET) differences between each season. Therefore, crop yield should increase in parallel with decreasing water consumption (or evapotranspiration) for optimal water use and increasing WUE. Additionally, different plant densities and late or early planting dates could affect morphological traits and grain yield.

In order to study the effects of planting date, deficit irrigation and plant density on yield, yield components and WUE of cumin, a field experiment was conducted as split-split plot based on randomized complete block design with three replications at the Agricultural Research Station, Ferdowsi University of Mashhad during growing season of 2017-2018. The main plots were irrigation levels including 100, 75 and 50% field capacity (FC). Three planting dates were studied in the split plots (December, March and April) and two plant densities (40 and 80 plant m-2) arranged as split-split plots. Soil moisture content was determined a day before and two days after each irrigation with TDR. Then, irrigation was done based on treatments during the growth period. Number of umbel per plant, number of seed per umbel, 100-seed weight, plant weight, seed yield and WUE were measured at the end of growing season. Analysis of variance were calculated using R software and Duncan's multiple range test was used at 5% probability level to compare the averages.

The results showed that the full irrigation (100% FC) of cumin in December with 80 plants m-2 had the highest number of umbel per plant, number of seed per umbel and seed yield, whereas, 100-seed weight and plant weight increased and WUE decreased with decreasing density (40 plants m-2) under 100%FC during December. The lowest seed yield were obtained from 75 and 50% FC in April with 40 plants m-2 (53.77% and 52.20% respectively) compared with December with 100% FC and 80 plants m-2. Seed yield were decreased by irrigation levels of 100 and 75% FC in March and April with 80 plants m-2 12.83, 29.24, 21.43 and 35.11%, respectively compared with 100% FC in December (80 plants m-2), despite the highest WUE. Therefore, increasing plant density with medium irrigation in late planting dates (March and April) can partially compensate decreasing cumin seed yield by increasing WUE. The correlation analysis showed that 100-seed weight and plant weight had significant negative correlation with WUE in full irrigation and two levels of water deficit. However, there was no significant correlation between WUE and seed yield under both levels of water deficit and full irrigation conditions.

The results of this study indicate that seed yield can be improved by increasing plant density when rainfall is proportional to plant water requirement in autumn and winter. In addition, increasing plant density in medium irrigation (75% FC) conditions in late planting dates (March and April) can increase WUE and produce high economic value.

In order to study the response of wheat (Triticum aestivum) cv. Chamran and wild barley (Hordeum spontaneum) to different herbicides، a pot dose response experiment was conducted in a completely randomized design with three replication at Research Greenhouse of Ferdowsi University of Mashhad in 2008. Different doses of herbicides including Clodinafop propargyl، Pinoxaden، Sulfosulfuron، and Metsulfuron-methyl+ Sulfosulfuron، were applied post-emergence at 2-3 leaf stage of wheat and wild barley and Isoproturon+Diflufenican was applied pre-emergence. Plant dry weight of each treatment was determined three weeks after herbicide application، then GR50، GR25، and herbicide selectivity indices were determined for each herbicide. Results showed that due to wild barley high tolerance، no herbicide could completely control this weed in wheat without injury to wheat. Among all herbicides، Metsulfuron-methyle+Sulfosulfuron was the best one for selective control of wild barley in wheat، which reduced wild barley biomass by 32% in recommended dose. Clodinafop propargyl and Pinoxaden، even at higher doses couldn’t reduce wild barley biomass and can not be used for wild barley control in wheat. Sulfosulfuron had little influence on wild barley at recommended dose، but at higher doses reduced both wild barley and wheat biomass significantly.

An experiment was conducted for evaluation the allelopathic potential of extract soybean shoot on seed germination and seedling growth of four weed species tumble pigweed, smooth pigweed, common lambsqurters and black nightshade. For each species a factorial experiment was used in a completely randomized design with three replications. Plant shoots were gathered in flowering stage and individually dried and then ground. Water extracts with concentrations of 5, 10, 20 and 40 % were prepared and distilled water was used as control. Seeds of weed sat in petri dishes. Then, their germination percentage determined after 11 days. The results showed that root length, germination rate and percentage reduced in weed species when concentration rate was increased. Black nightshade had most germination percentage (88.14), root length (46.4 mm) and germination uniformity (1.5 days). Therefore, it affected with soybean shoot extract less than other weed species. Tumble pigweed had most germination rate (3 days) and its required time to achieved 10, 50 and 90% maximum germination, was about 2, 2.5 and 4 days respectively. Therefore, It was better than other species. Most inhibition effect of extracts on germination percentage belonged to smooth pigweed.

This study was conducted in a sugar beet field at Collage of Agriculture Experimental Station, Ferdowsi University of Mashhad, Iran. In order to describe the pattern of spatial variations and density of Chenopodium album, Solanum nigrum, Amaranthus sp., Portulaca oleracea, Echinochla crus-galli, and Convulvulus arvense as the main prevalent annual and perennial weeds of sugar beet fields, geostatistic methods were used. Samples were taken by systematic method from the corners of (7m × 7m) grids, using (0.5m × 0.5m) quadrates in three stages (before application of herbicides, after herbicide treatment, and before harvesting sugar beets). The integrity of spatial variation of variables was determined by using variogram functions and distribution maps of species. The variograms indicated that variations of all variables did not happen by chance. The maximum and minimum ranges of variation were observed in Solanum nigrum (by 142.7m) and Portulaca oleracea (by 1.5m), respectively. Both maximum and minimum ranges of variations were related to pre herbicide application. The highest and the lowest spatial correlations were related to Amaranthus sp. (in the third sampling treatment) and Solanum nigrum (in the first stage of sampling), respectively. The spatial distribution maps confirmed the patchiness distribution of the weeds. The patch of weed was constructed from a dense point at the center, gradually tapering toward the edges. The patches were skewed across the rows and irrigation channels. The structure of patches altered during the growing season. Any information on the distribution of weeds in the fields can be useful to improve decision makings in relation to applying the herbicides, selecting the herbicide type or applying the amount of herbicide. Also it can be useful to better design of weed control programs.