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IntroductionCropping 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.Materials and MethodsA 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.ResultThe 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.ConclusionCorn-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.

Introduction 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. Materials and Methods 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. Results and Discussion 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. Conclusions 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.

Introduction: Weed cause enormous loss of chickpea yield and its quality. Photocontrol of weeds (soil cultivation in darkness) is a preventive weed control method, the basic aim of which is to reduce the germination of light sensitive weed seeds by excluding light during soil disturbance, in order to reduce the emergence of weeds in the crop. Considerable research has examined the potential use of lower-than-labeled herbicide doses. There are reasons for the potential successful use of reduced herbicide doses: (i) registered doses are set to ensure adequate control over a wide spectrum of weed species, weed densities, growth stages, and environmental conditions; (ii) maximum weed control is not always necessary for optimal crop yields; and (iii) combining reduced doses of herbicides with other management practices, such as tillage or competitive crops, can markedly increase the odds of successful weed control. This study was conducted to evaluate the photocontrol of weeds and application of reduced dosage of Imazethapyr and trifluralin herbicides on weed control and yield of chickpea. Materials and Methods: The experiment was designed as a strip plot based on a complete randomized block with three replications. The experiment had 3 factors: main plot consisted of tillage method at 3 levels (night tillage, day tillage, light-proof cover tillage), subplot consisted of Trifuralin (480, 960 and 1440 grams of active ingredient per hectare) Imazethapyr (50, 100 and 150 grams of active ingredient per hectare), weed infestation and weed free were considered as control. During the growing season, six sampling steps (28 days after planting (410 Growth Degree Day (GDD)), (45 days after planting (715 GDD)), (57 days after planting (975 GDD)), (70 days after planting (1280 GDD), (75 days after planting (1620 GDD)), (90 days after planting (2025 GGD)) were carried out. For statistical analysis the data normality of the distribution were analyzed with Sigma plot software, and if necessary, the data transforming and then ANOVA was performed using MSTATC. The means were compared using Duncan's multiple range test and graphs were drawn using Excel and Sigma plot software. Result and Discussion: In the growing season, the application of herbicide had significant effect (P≤ 0.05) on weed density. In all stages of sampling, weed density was higher in light-proof cover tillage treatments than day and night tillage operations. According to the results based on the type of tillage, night tillage and light-proof cover tillage treatments did not reduce weed density compared to day tillage. In the reduced Imazethapyr application, there was significant difference at 1620 GDD with others, but this amount of application did not effectively control weeds. In treatment of 1280 GDD, the amount of reduced application of Trifuralin was significantly different with other amounts but could not control weeds. However, there was no significant difference between the amounts of Trifuralin from this stage until the end of the growth season. By examining the biomass of chickpea during the growing season in the applied amounts of herbicides, it was determined that the growth of all treatments was the same order of 1200 GDD. From this stage, the difference between treatments increased until the end of the growing season, in the end of the growing season, control of weed control was the highest and control without chickpea was the least biomass. The effect of herbicide application dosage on the density of the weeds was significant (P≤ 0.05). Chickpea grain yield in light -proof cover tillage was 45 percentage lower than night-time tillage and day time tillage treatment and there were no significant differences between night-time tillage and day-time tillage treatment. The lowest and the highest yield was respectively in weed infestation (1151 Kg/ha) and weed control (1977 Kg/ha) and yield in the dosage of herbicides. Did not differ significantly. The results of this experiment show that reduced dosage of herbicides can control weed without negative effects on chickpea yield. Conclusion: The results showed that weed density and weed biomass was more than in light-proof cover tillage treatment compared to night and day tillage and there were no significant differences (P≤ 0.05) between night and day tillage. Weed biomass showed no significant differences between herbicide treatments. The reduced dosage of herbicide in Imazethapyr treatment did not have enough control but there were no significant differences between herbicide treatments. Chickpea yield had no significant difference (P≤ 0.05) between reduced, recommended and increased dosage herbicides

Introduction: The assessment of the effect of mixtures could be based on various concepts whether we work within toxicology, pharmacology or weed control. Combinations of certain herbicides can give better weed control than use of the individual herbicide alone and/or loss of weed control when use of certain other herbicides in combination. Predicting the joint action of mixtures is extremely difficult, unless the compounds are known to interact at the same site of action. These most common methods to analyze the joint action of herbicide mixtures are the Additive Dose Model (ADM) or the Multiplicative Survival Model (MSM). The ADM assumes the two compounds have similar modes of action (do not interact) in the receiver plant, i.e. effective doses of each component will not change by mixing. ADM has been widely accepted as a valid method to estimate joint action of mixtures sharing the same or similar action mechanisms in the receiver plant. MSM has been reported to yield more accurate results for mixture toxicity than ADM do when the components exhibited different or dissimilar modes of action in the receiver plant. ADM or Concentration Addition (CA) is used here to test for deviation of additivity of doses using the ADM isoboles as reference; any deviation from the ADM is characterized by antagonism when the efficacy of a mixture is lower than predicted by the reference model and synergistic when the efficacy is higher than predicted. Materials and Methods: In order to determine joint action of some usable important broadleaf herbicides in sugar beet, six experiments were conducted at the research glasshouse in Faculty of Agriculture, Ferdowsi University of Mashhad, Iran. The plants were sprayed with seven doses of commercial formulation of desmedipham + phenmedipham + ethofumesate (Betanal Progress- OF®, 427 g a.i. L-1, Tragusa, Spain), chloridazon (Pyramin®, 1361 g a.i. L-1, BASF, Germany), clopyralid (Lontrel®, 149 g a.i. L-1, Golsam, Gorgan, Iran) either alone or in binary fixed-ratio mixtures of the three herbicides. The ratio of the herbicides of the binary mixtures were chosen with the aim of obtaining a contribution to the overall effect of the two herbicides of 100:0, 75:25, 50:50, 25:75, and 0:100 for seven-mixture-ratio experiments. Spraying was performed by overhead trolley sprayer (Matabi 121030 Super Agro 20 litre sprayer), 8002 flat-fan nozzle at 300 kPa and a spray volume of 200 Lha-1. The plants were treated at 21 days (at the four- to six-true leaf stage) after planting. Dose-response curves were estimated by fitting a three log-logistic dose–response model against dose for ED50 and ED90 response levels. ADM was used as reference model of joint action with their equations. As the results with the herbicide mixtures originate from up to twelve separate experiments it was necessary to standardize the x- and y-axes so that the ED50, ED80 and ED90 doses of the herbicides applied separately were always fixed to 1. Results Discussion: The results showed that mixtures of chloridazon and clopyralid were less phytotoxic than predicted by ADM particularly in Amaranthus retroflexus at ED50 and ED80 response levels. These binary mixtures of herbicides were either followed ADM or less than predicted by ADM in Solanum nigrum. In contrast, mixture of desmedipham + phenmedipham + ethofumesate and clopyralid was synergistic in both species. Whereas desmedipham + phenmedipham + ethofumesate and chloridazon binary mixture was synergistic in Solanum nigrum to followed according to ADM in Amaranthus retroflexus. Conclusion: The present study has revealed that mixtures of photosystem II, lipid biosynthesis and auxin inhibitor herbicides either followed ADM, or performed better than predicted by ADM, i.e. applying mixtures of these herbicides will not result in an excessive use of herbicide compared to applying the herbicides separately. In contrast, mixtures of chloridazon and clopyralid were trend antagonistic and the two herbicides should not be applied in mixture.

Introduction: Adjuvant application is one of the most important ways to increase herbicide efficacy and decrease environmental damaging effects of herbicides. In general, It has displayed that a very few of the spray droplets retained on the surface of leaf plants and the majority of them bounce off the leaf surface. Therefore, in spraying processes, adjuvant designed to enhance the absorbing, emulsifying, dispersing, spreading, sticking, wetting, or penetrating properties of pesticides. Adjuvant are most often used with herbicides to help a pesticide spread over a leaf surface and penetrate the waxy cuticle of a leaf or to penetrate through the small hairs present on a leaf surface. Surfactants and crop oils are two types of adjuvant that are used for increasing efficacy of herbicides. In many cases, significant increases have been observed in biological activity with the addition of surfactants or crop oils. For example, the performance of specific graminicides and some sulfonylureas is usually increased by the addition of tank-mix oils. It is generally accepted that the benefit of oils is related to their ability to increase the drying period of droplets during their fly time before their impact on the plants, to improve the spreading of the deposit on difficult-to-wet targets (mainly Graminaceae), to act as solubilizing agents, and above all to enhance the penetration of herbicides into the plants. Among commercially available adjuvants, emulsified vegetable oils have been shown to increase droplet retention and spreading, and enhance absorption and translocation of active ingredients. It has been reported that efficacy of atrazine, bentazone, phenmedipham and rimsulfuron on various weeds were increased by the addition of rapeseed oils to solution spray. Materials and Methods: In order to evaluate the effect of adjuvant concentrations on surface tension of aqueous solutions, an experiment was conducted as completely randomized design with 4 replications at 8 levels of adjuvants (0, 0.01, 0.05, 0.1, 0.15, 0.2, 0.25 and 0.3 (% v/v)). Moreover, the effects of surfactant and vegetable oil on the efficacy of mesosulfuron + iodosulfuron commercial mixture on littleseed canarygrass (Phalaris minor Retz.) were investigated under greenhouse conditions in Agriculture Faculty of Ferdowsi University of Mashhad. Greenhouse study was conducted in 6 concentration levels of mesosulfuron-methyl+idiosulfuron (0, 5.62, 11.25, 22.5, 33.75, and 45 g ai ha-1). This herbicide was applied alone and with these adjuvants including: (i) citogate (a nonionic surfactant), (ii) castor oil and (iii) rapeseed oil each one of them at two levels 0.1 and 0.2 %, the experiments were arranged in a completely randomize design with a factorial arrangement of treatments with four replications. Results and Discussion: When adjuvants alone were applied against littleseed canarygrass, none of them had not phytotoxic effect so that fresh weight and dry weight of plants did not decrease significantly as compared to the control. The results of lab experiment showed the lowest and highest surface tension belonged to Citogate and rapeseed oil, respectively. Also the results of greenhouse experiment indicated all adjuvant were able to increase the efficacy of mesosulfuron + iodosulfuron herbicide. Relatively potency (R) of dry weight increased with usage of Citogate surfactant, castor and rapeseed oils to 1.4, 1.35 and 1.13 respectively. The Citogate surfactant leads to the greatest enhancement of herbicide efficacy. The foliar activity of the tested herbicide enhanced with increasing adjuvant concentration from 0.1 to 0.2 (% v/v). According to the accessible information, surfactants (nonionic Citogate) are suitable for reduction surface tension. Previous studies showed that nonionic surfactant was too effective in decreasing surface tension of spray solution. Despite, it has been observed that vegetable-derived oils could not greatly decrease surface tension. For example, castor oil decreased surface tension of water from 73 to 71.5 mN/m. Whereas, nonionic surfactants can lower the surface tension of the spray solution to 33 to 34 mN/m. It seems that drop in surface tension by the citogate surfactant is considered sufficient to decrease the contact angle of spray solution proplets and makes an extension of droplet on leaf plant. Ultimately, spray droplet spread can be very important in obtaining the desired foliar coverage for contact pesticides and appears to play a role in moving the active ingredient to more absorption sites on the plant. Conclusion: Based on the results of this study; the following conclusions can be made: (1) the ranking of adjuvants to enhance the tested herbicides efficacy was alike this order: citogate > castor oil> rapeseed oil.

Introduction: During last century, population explosion has been pressing man to produce more supplies of food by consuming more energy in agroecosystems like applying chemical management strategies. herbicides have increasingly become a key component of weed management programs. In Iran, using herbicides led to increasing wheat yield about 20% and 22% in rainfed and irrigated farms respectively (20). Nonetheless, herbicides have also a negative impact on environment. A tool for reducing the herbicide usage which allows to decreasing their cost and side effects is the use of adjuvants. They increase the effectiveness of the post-emergence herbicides. Some adjuvants have toxic effects on living organisms such as Polyethoxylated tallowamine adjuvants that they are very toxic in fairy shrimp (Thamnocephalus platyurus) (6). Vegetable oils are not phytotoxic and likely are degraded and metabolized quickly in the environment (8). Sethoxydim is an acetyl coenzyme A carboxylase (ACCase) inhibitor that is considered to be a key enzyme in lipid biosynthesis. Similar to other foliar applied herbicides, it need to be associated with an adjuvant for more effective control. Vegetable oils can be developed characteristics of sethoxydim solution such as surface tension and spry drop diffusion. Therefore, the objective of this research is to determine the effect of vegetable oils on the surface tension, diffusion and efficiency of sethoxydim to control wild oat (Avena ludoviciana Durieu.). Materials and Metods: To evaluate the effect of vegetable oils on properties of sethoxydim solution, a series of experiments were separately conducted at Ferdowsi University of Mashhad and Khorasan Science and Technology Park in 2012. For evaluating the effect of vegetable oils on surface tension of distilled water and sethoxydim solution and the sethoxydim efficiency on wild oat control, three experiments were conducted as factorial based on completely randomized design. In other experiment the vegetable oils application on diffusion of sethoxydim was conducted also based on a completely randomized design. A K100 tensiometer was used to measure the surface tension of water and sethoxydim solution containing vegetable oils. For measuring the diffusion of sethoxydim solution containing vegetable oils, water sensitive paper was used. The surface changing color was evaluated by using MIP software. Wild oat seeds were collected from plants in the field near the research greenhouse at Ferdowsi University of Mashhad, Iran. They were dehulled and placed in 11 cm diameter Petri dishes on top of a single layer of filter paper (Whatman International, Maidstone, UK). Then, 10 mL of 0.2% KNO3 solution were added to each Petri dish and the seeds were incubated for 48 h at 4–5°C in the dark. The seeds then were germinated under temperature and relative humidity control conditions in the dark (16 h at 20°C and 8 h at 10°C, with 45% and 65% relative humidity, respectively). By this method, 92–98.5% of the seeds germinated. Ten germinated seed were planted in each 1.5 L plastic pot that was filled with a mixture of sand, clay loam soil, and peat (1:1:1; v/v/v). The pots were sub irrigated every 3 days. The seedlings were thinned to four per pot at the one leaf stage and 40 mL of a water-soluble N: P: K (20:20:20) fertilizer, at a concentration of 3 g of fertilizer per liter of tap water, were supplied to each pot. Results and Discussion: The results showed that the use of vegetable oils except castor oil caused reduction in the surface tension of distilled water. About the surface tension of the sethoxydim solution, all vegetable oils significantly reduced surface tension. There is anegative relationship between surface tension of sethoxydim solution and efficiency of sethoxydim. Regression analysis results of the surface tension and spray deposit distribution on sensitive paper percent showed strong negative relationship them. Effects of adjuvants on herbicide surface tension have been showed by other researches. As judged by the ED50 and relative potential showed in table 3, all vegetable oils led to increased herbicide efficiency. Using adjuvants led to increasing performance of herbicide. Conclusion: Using of vegetable oil can be reduced needed sethoxydim for controlling wild oat. Reducing surface tension of herbicide solution can be known as a main reason for improvement of herbicide efficiency in the presence of vegetable oils. Low surface tension lead to more distribution of herbicide solution on leaf surface and eventually increased herbicide absorption.

Introduction: Farmers usually combine various herbicides with the aim of reducing the number of machinery passes across the field, preventing weed resistance to herbicides, and saving time and money. Combination of herbicides is not only recommended for the management of herbicide resistance, but for increasing efficacy compare with a single herbicide application and expanding spectrum weed control. Materials and Methods: In order to assess the mixing herbicides that used in wheat, several experiments were conducted in the Research greenhouse and Farm of Agricultural Faculty of Ferdowsi University of Mashhad, Iran in 2013. The greenhouse experiments were arranged in a completely randomize design with a factorial arrangement of treatments with four replications. Greenhouse studies were included two combination experiments. Experiments included of 7 doses (0, 2.25, 4.5, 9, 13.5, and 18 g ai ha-1) of mesosulfuron-methyl+iodosulfuron and (0, 5.6, 11.25, 22.5, 33.75, and 45 g ai ha-1) of pinoxaden (Axial 10% EC, EC; Syngenta, Switzerland) alone on wild oat (Avena ludoviciana Durieu) and littleseed canarygrass (Phalaris minor Rtez.). Wild oat seeds were sown in pots directly. Littleseed canarygrass seeds were placed in petri dishes with 9 cm diameter which contains a layer of filter paper then 6 ml of KNO3 solution (2 g L-1) was added to each petri dish. Petri dishes were kept for 10 days at 4 to 5 °C in the refrigerator in darkness condition and then transferred to a germinator with 20/10 °C temperature in 45/65% relative humidity for a 16/8 h day/night. Then, they were planted in 1L plastic pots filled with a mixture of clay, loam soil, and sand (1:1:1 v/v/v). The pots were irrigated every two days. The seedlings were thinned to 4 plants in per pot. The spray treatment was done at the three to four-leaf stage by using an overhead trolley sprayer (Matabi 121030 Super Agro 20 L sprayer; Agratech Services-Crop Spraying Equipment, Rossendale, UK), equipped with an 8002 flat fan nozzle tip delivering 200 L ha-1 at 2 bar spray pressure. Four weeks after spraying, the plants of the experimental units were harvested and oven-dried at 75°C for 48 h, then weighed. The greenhouse temperature varied from 18–25 °C during the day and 14–21°C at night. Field trial was conducted in completely randomized block design with three replications at Research Farm of Agricultural Faculty of Ferdowsi University of Mashhad, Iran in 2014. Because the appropriate ED50 obtained in the greenhouse therefor he recommended doses were used for field trial. Minitab 16.0 software was used for variance analysis and Mean comparison also for regression analysis, R software was applied. Results and Discussion: Greenhouse experiment results showed that pure application of mesosulfuron-methyl+iodosulfuron and pinoxaden herbicide was effective on wild oat and littleseed canarygrass. The results of mixing experiments on wild oat and littleseed canarygrass showed that mixture of mesosulfuron-methyl+iodosulfuron with pinoxaden had additive effect of both species. ED50 of different ratios of the two herbicides showed that maximum efficacy (maximum intensity effect) in decreasing dry weight of wild oat was related to ratio 100: 0 mesosulfuron-methyl+iodosulfuron and pinoxaden with ED50= 2.16 and minimum efficacy (minimum intensity effect) was related to ratio 75:25 mesosulfuron-methyl+iodosulfuron and pinoxaden with ED50= 4.22. The results of the field almost were consistent with the results of the greenhouse so that the different ratios no significant difference was observed in both species of wild oat and littleseed canarygrass. All herbicide treatments resulted in at least 85.4% and 86.86% reduction biomass and population of wild oat. Except control treatments, all tank mixing ratios of mesosulfuron-methyl+iodosulfuron and pinoxaden weren’t significantly different. On the other hand, jointed effects of the two herbicides on wild oat in field experiment had the same effect as when each herbicide applied separately. Also, comparisons between greenhouse and field results showed that twice condition have same response. The results of yield and yield components showed that parameters of grain yield and biological yield was significant at the 5% level. Conclusion: None of herbicides had effect on others and the results of greenhouse were consistent with field experiment. It may be possible without diminished performance, these herbicides were used to postpone weed resistance in weed management.

Introduction: Potato (Solanum tuberosum) is an annual crop that belongs to the Solanaceae family. It contains abundant starch and ranks as the world’s fourth most important food crop, after maize, wheat and rice. It is one of most important crops in Iran. The total area under potato cultivation was 186 thousand hectares during 2011 and 2012. Weeds are one of the greatest limiting factors to efficient crop production. Application of herbicides is the key method of weed control in potato fields, both in the world and Iran. Herbicides that commonly are used for weed control in potato fields of Iran are metribuzin, paraquat, rimsulfuron, pendimethalin and sulfosulfuron. Materials and Methods: In order to study the effect of herbicides to control weeds of potato fields, field experiments were conducted at the Agricultural Research Center of Jiroft and Karaj. Plots were located on a sandy loam soil with a pH of 7.4 in Jiroft, and loamy soil with a pH of 7.7 in Karaj. The experiments were conducted during 2009-2010. Potato variety used in Jiroft was Santeh and Satina in Karaj. The experimental design was the randomized complete blocks design (RCBD), with four replications. Weed control treatments included paraquat (20% SL) at 3 lit/ha as early post- emergence, metribuzin (70% WP) at 750 gr/ha as preemergence, pendimethalin (33% EC) at 3 lit/ ha as preemergence, rimsulfuron (25% DF) at 60 gr/ha applied with adjuvant cytogate at 2.5% volume of water early post emergence, sulfosulfuron (75% DF) at 35 gr/ha (postemergence), metribuzin at 750 gr/h + rimsulfuron at 60 gr/ha with adjuvant cytogate at 2.5% volume of water, , metribuzin at 750 gr/ha+ pendimethalin at 3 lit/ ha, metribuzin at 750 gr/ha+ sulfosulfuron at 35 gr/ha, paraquat at 3 lit/ha + rimsulfuron at 60 gr/ha with adjuvant cytogate at 2.5% volume of water, paraquat at 3 lit/ha + pendimethalin at 3 lit/ha, paraquat at 3 lit/ha + sulfosulfuron at 35 gr/ha and hand weeding. Each plot was 4 m wide and 8 m long with 4 rows and 75 cm distance among rows. Density and dry weight of weeds and potato yield were recorded. Results and Discussion: Results indicated that 6 broadleaf weeds were dominant in the fields included prostrate pigweed (Amaranthus blitoides), bindweed (Convolvulus arvensis), malva (Malva neglecta) in Jiroft, and red rooted pigweed (Amaranthus retroflexus), datura (Datura stramonium), bladder hibiscus (Hibiscus trionum) in Karaj. Visual observation confirmed that the most weeds were effectively controlled using herbicide treatments. The statistical analysis of the data revealed that the herbicides applied for weed control in potato have significantly decreased weed density and dry weight. The lowest weed density and dry weightof prostrate pigweed were observed in plots treated with paraquat + rimsulfuron. This treatment reduced density and dry weight of prostrate pigweed by 70% and 69% in Jiroft. However, Red rooted pigweed was controlled better than prostrate pigweed in Karaj. All treatments of mixed herbicides reduced density and dry weight of red rooted pigweed by 100% in Karaj. Maximum control of bindweed was obtained with metribuzin + rimsulfuron. This treatment reduced density and dry weight of bindweed by 35 % in Jiroft. The highest control of malva was achieved with metribuzin plus rimsulfuron in Jiroft. This treatment reduced density and biomass of malva by 61 and 56%, respectively. The best control of datura was obtained with paraquat plus rimsulfuron in Karaj. This treatment reduced datura biomass by 98%. Maximum control of bladder hibiscus was obtained with paraquat plus rimsulfuronin which dry weight was reduced by 98%. The highest potato yield (48 ton/ha) was obtained by application of metribuzin plus rimsulfuron in Jiroft. Potato yield was also increased with this treatment by 40%. The least potato yield (32 ton/ha) was obtained with pendimethalin in Jiroft. The maximum potato yield (32 ton/ha) was obtained by application of paraquat plus rimsulfuron and paraquat plus pendimethalin in Karaj, and minimum potato yields were obtained by application of sulfosulfuron and pendimethalin. Conclusion: Results of both years and locations showed that application of herbicide mixture improved weed control and potato yields. Pendimethalin and rimsulfuron are suitable alternatives for herbicide rotations in potato fields and can replace metribuzin and paraquat.

Introduction: Ranunculus ficariais L. (Fig buttercup or Lesser Celandine) is an herbaceous perennial belongs to Ranunculaceae (buttercup family) that behaves as a ground cover. It is a spring ephemeral that grows from a cluster of tuberous roots in late winter or early spring. It has glossy, dark green (sometimes slightly mottled), fleshy leaves on long petioles, and cordate to oblong-cordate in shape. The margins can be entire or wavy (1, 28). Flowers 15-60 mm in diameter, solitary at the end of each stem branch. Flowers have 3 sepals (rarely more), 3 petals, bright, pale to golden yellow, very rarely orange, shining on inside, receptacle concave, with short, pale simple glandular hairs. Achenes either abortive or maturing in a globular cluster, when mature 2•5-5•0 x 1•7-3•5 mm, more or less globular or obovoid, usually with few to numerous very short simple glandular hairs. This invasive weed spreads primarily by vegetative means through abundant tubers and bulblets, each of which can grow into a new plant once separated from the parent plant. The prolific tubers may be unearthed and scattered by the digging activities of some animals, including well-meaning human weed pullers, and spread to new sites during flood events (28). This weed has two subspecies, R. ficaria Subsp. ficaria and R. ficaria Subsp. bulbilifer that the second is probably the only subspecies of mountainous regions in many areas. It is an abundant weed of lawns and gardens, where it spreads rapidly and is very difficult to eradicate. According to our observations probably R. ficaria spread by tubers from mountains to fields that near to mountains in Lorestan province of Iran. The Aim of this study was assessment of this weed to improve its management practices in the wheat fields. Materials and Methods: In order to study the some aspects of biology and morphology of tubers root and seeds of R. ficaria , two experiments were conducted at Laboratory of Gorgan University in 2011. For breaking root tubers dormancy, root tubers incubated for different storage time (7, 14, 21 and 28 days) and different storage temperature (2, 4 and 8˚C). To evaluate the effect of tuber size, six groups (very small

Introduction: There are many reasons for no effectiveness of herbicides on weeds, including the incorrect herbicide, the insufficient use of herbicide, the unprincipled sprayer, spraying at the wrong time especially adverse weather conditions, and a factor that often overlooked is the "water quality in herbicide spray tank". Most of the herbicides are mixed with water and applied as a spray. Obviously water quality is an extremely important issue. Water quality factors in this regard that effect on uptake and translocation of herbicides included as water hardness, pH, bicarbonate ion concentration, turbidity, organic matter and other substances. Hardness is determined by the amount of calcium and magnesium present and is expressed as calcium carbonate (CaCO3) equivalent in parts per million. Petroff (27) classified water based on hardness: water with a hardness 0-75 ppm is considered “soft” water, 75-150 ppm is “medium hard”, 150-300 ppm is considered “hard”, and more than 300 ppm is “very hard”. Hard water is a problem in over 85% of the United States according to the US Geological Survey. The contrast between the herbicides and dissolved ions depend on amount and type of minerals in the spray tank. So that different herbicide may show different responses to the same action. If soft water is not available, surfactant and chemicals additives such as ammonium sulfate (AMS), ammonium nitrate (AMN) and urea- ammonium nitrate can be added to the spray tank to increase herbicide efficacy (7). These compounds prevent from the adverse effects of the ions in water. Glyphosate and nicosulfuron belong to two different chemical families of herbicides and are soluble in water. Therefore, water quality such as the presence of calcium carbonate may have a significant effect on these herbicide performances, while removing the inhibitory effect of water hardness by adding nitrogen compounds such as ammonium sulfate need to experiment. According to the above, basic experiments carried out as the influence of adding ammonium sulphate to spray solution of calcium carbonate-containing glyphosate and nicosulfuron on barnyardgrass and velvetleaf control. Materials and Methods: Four experiments were performed as factorial arrangement of treatments 6×2 based on completely randomized design with six replications (+six control pots for each weed species) at Research Greenhouse of the Ferdowsi University of Mashhad in 2010. Factors were included different concentrations of calcium carbonate (CaCO3; Merck, Germany) of water in spray tank at six levels 0, 100, 200, 300, 400 and 500 ppm in deionized water (w/v) in combination with 0 (-AMS) or 3 kg/ha (+AMS) ammonium sulphate (Merck, Germany) as adjuster the hardness. Glyphosate (Roundup®) and nicosulfuron (Cruse®) herbicides were applied post emergent at 385 and 550 mL ha-1 as commercial products (158 and 22 g ai ha-1; based on ED50 outcome preliminary test (12), recpectively) at the 3-4 leaf stage of the weeds (barnyardgrass and velvetleaf) in a spray volume of 250 L ha-1. Four weeks after treatment, survival, plant height, leaf area, and shoot dry weight of weeds (% control) were calculated. The data of experiment were subjected to ANOVA using MSTATC software. Means of the treatments were separated using Duncan’s Multiple Range Test at α = 0.05. Also, based on the distribution of data, regression analysis was used as linear, two, and third-degree polynomial by EXCEL 2007. Results and Discussion: The results showed a significant reduction (p≤0.01) for survival, plant height, leaf area, and shoot dry weight of weeds (% control) with addition of calcium carbonate in spray tank of glyphosate and nicosulfuron herbicides, but this effect was not similar. So that, 500 ppm Ca2+ to the nicosulfuron spray solution compared with its absence increased barnyardgrass and velvetleaf biomass (% control) 16 and 50%, respectively. The corresponding values for glyphosate were 78 and 51%. Accordingly, Nalewaja et al. (24) reviewed the effect of different calcium compounds such as calcium carbonate (0.02 mol) in water as a solvent nicosulfuron herbicide (15 g ai ha-1; 160 L ha-1) interaction to seven surfactants on finger grass (Digitaria sanguinalis L.) at greenhouse conditions found that CaCO3 across seven surfactants reduced about 8% nicosulfuron performance. In research conducted by Buhler and Burnside (5) concluded that an increase in calcium ion (prepared from CaCl2) to 2 mmol in spray tank was not affected on glyphosate (400 g ai ha-1; 190 L ha-1) performance. With the increasing of Ca++ to 8 mmol, was reduced significantly (P≤0.05) toxicity herbicide on oat (Avena sativa L.) from 80 to less than 20%, 14 days after spray at the greenhouse experiment. Adding ammonium sulphate (+AMS) decreased the antagonistic effects of water hardness, and increased herbicides efficacy on barnyardgrass and velvetleaf. However, the synergistic effect of +AMS on velvetleaf control by glyphosate was higher. Green and Cahill (10) concluded adding 2% AMS to spray tank increased the pH of nicosulfuron solution from 4.6 to 4.7 and finger grass was well controlled by this herbicide because of increasing nicosulfuron solubility from 12 to 16%. In research conducted by Mueller et al. (22), the presence of calcium (Ca++) and magnesium (Mg++) ions concentration of 250 ppm reduced the effectiveness of three types of glyphosate salt, but adding 2% by weight of ammonium sulfate (AMS) to the spray tank overcame to the ions antagonistic effect. Conclusion: Results of current experiment emphasized the role of water hardness (CaCO3) in spray tank of glyphosate and nicosulfuron on barnyardgrass and velvetleaf control.

Introduction: Many factors affect the absorption, transport and performance of herbicides, include; physical factors (such as the orientation, shape, size, cuticle thickness, and its amount downy of the plant leaves), physiological factors (such as the growth stage and its succulence), environmental factors (like rainfall after spraying, relative humidity, wind, and temperature), as well as water quality in spray tank (32). The quality of natural water resources is very important, because the water passes through soil and rocks and dissolve natural salts and transfer them to groundwater reserves (12). pH is a chemical scale for measuring the concentration of hydrogen ions (H+) in the water (21). When pH of solution is less than herbicides pKa (ionic dissociation constant), increasing pH can increase the solubility of herbicides, especially when the absorption limitation of herbicide is because of its solubility (14). To investigate the effect of water pH in herbicide spray tank, testing the effectiveness of weed control is appropriate method. The different species of weeds may have different amounts of ions in the tissue that showed different responses to herbicide solution (14). Accordingly, these basic experiment conducted to study the pH variation of water in spray tank on glyphosate (Roundup®) and nicosulfuron (Cruse®) performance on barnyardgrass [Echinochloa crus-galli (L.) P. Beauv.] and velvetleaf (Abutilon theophrasti Medicus.) control in the greenhouse condition. Materials and Methods: Two separate experiments were performed as factorial arrangement of treatments 2×7 based on completely randomized design with six replications at Research Greenhouse of the Ferdowsi University of Mashhad in 2010. Factors included were: pH at 7 levels (4, 5, 6, 7, 8, 9, and 10) obtained by using buffer prepared solutions (+3 control pots for each pH level), and two weeds (barnyardgrass and velvetleaf). Glyphosate and nicosulfuron herbicides were applied post emergent 158 and 22 g ai ha-1 (based on ED50 outcome preliminary test (11)), recpectively, at the 3-4 leaf stage of the weeds in a spray volume of 250 L ha-1. Four weeks after treatment, survival, plant height, leaf area, shoot fresh and dry weight of weeds (% control) were calculated. The data of experiment were subjected to ANOVA using MSTATC software. Means of the treatments were separated using Duncan’s Multiple Range Test at α = 0.05. Based on the distribution of data, regression analysis was used as two, third, and four-degree polynomial. Result and Discussion: The results showed significant effect (P≤0.01) of water pH variation in spray tank of herbicides on survival, plant height, leaf area, shoot fresh and dry weight of weeds (% control). Nicosulfurone herbicide in water pH equal 7 and 8 showed the highest effect on barnyardgrass weed, so that, the highest activity of nicosulfuron herbicide on velvetleaf was found in water pH= 8. Whereas, glyphosate herbicide in water pH equal 6-7 and 6 showed the highest effect on barnyardgrass and velvetleaf, recpectively. The total, more alkaline pH of water in spray tank was suitable for nicosulfuron compared to glyphosate performance (9, 28). Comparison between two weeds was showed that nicosulfuron effect on barnyardgrass control was more than of velvetleaf. So that in the best performance of the herbicide (water pH= 8), values of survival, plant height, leaf area, fresh weight and dry weight (% control) were estimated equal 25.8%, 16.7%, 21.6%, 4.6%, and 2.6% for barnyardgrass, respectively. The corresponding values for velvetleaf were 50.0%, 61.1%, 53.6%, 32.9%, and 24.5%, respectively. In general, the solubility of sulfonylurea herbicides in water decreases with decreasing pH. Therefore, an acidic solvent prevent from their optimal distribution and their efficiency are reduced (18, 22). In this regard, Matocha and Senseman (15) reviewed the half-life of Trifloxysulfuron herbicide in water pH 5, 7 and 9 and found that this herbicide hydrolyzed faster in acidic pH than neutral/ alkaline pH. Green and Cahill (9) also were showed when alkaline agents added to spray tank, increased the pH of nicosulfuron solution and finger grass (Digitaria sanguinalis) was well controlled by this herbicide. The researchers, increasing the nicosulforon performance on weed knew because of its higher solubility at high pH. In research conducted by Buhler and Burnside (4) concluded that an increase in the water pH of glyphosate spray tank (400 g ai ha-1) by from 2.4 to 7 and 9, reduced herbicide performance on oat (Avena sativa) 14 days after spray at the greenhouse experiment (P≤0.05). So that, shoot fresh weight of oat was lost by 69 percent at pH= 2.4 (compared to the control without spraying). The corresponding values for pH 7 and 9, were estimated 62% and 55%, respectively. Field test results also coincided with greenhouse experiment (4). Conclusion: Results of current study emphasized the role of water pH in spray tank of glyphosate and nicosulfuron on barnyardgrass and velvetleaf control.

Introduction: Desmedipham + phenmedipham + ethofumesate, phenylcarbamates + benzofuranyl alkanesulfonate herbicides, is widely used for post-emergence broad-leaved weed control in sugar beet. Chloridazon, a pyridazinone herbicide, is used as a pre- and post- emergence herbicide in sugar beet. Desmedipham, phenmedipham and chloridazon, are photosystem II (PSII) inhibitors, their translocation via xylem are slow, mostly absorbed not only by roots, but also by foliage. Their mode of action is through the blocking of electron transfer between the primary and secondary quinones (QA and QB) of PSII by binding to the QB-binding site and accepting electrons from QA in the chloroplasts. Measures of changes to the chlorophyll fluorescence induction curve (Kautsky curve), is a rapid, non-invasive and simple method for monitoring the physiological status of the photosynthetic apparatus in the plant. There are three phases found on the O, J, I and P steps. These phases primarily point out photochemical events relevant to PSII. The three phases are described as follows: at the O-J phase complete reduction of the primary electron acceptor QA of PSII takes place from 50 μs to 2 ms, the J-I phase corresponds to electron transfer from QA to QB happens between 2 to 30 ms and the I-P phase corresponds to the release of fluorescence quenching by the oxidized plastoquinone pool taking place within 30-500 ms. Materials and Methods: In order to determine how exposure affects the fluorescence induction curve (Kautsky curve) and its parameters, two dose-response experiments carried out for chlorophyll fluorescence measuring. The treatments involved desmedipham + phenmedipham + ethofumesate at 0, 51.38, 102.75, 205.5, 308.25, 411, 616.5 and 822 g a.i. ha-1 and chloridazon at 0, 81.25, 162.5, 325, 650, 1300, 1950 and 2600 g a.i. ha-1 on common lambsquarters (Chenopodium album L.) and common purslane (Portulaca oleracea L.) at the research glasshouse of Agricultural Faculty of Ferdowsi University of Mashhad, Iran. Spraying was performed by overhead trolley sprayer (Matabi 121030 Super Agro 20 litre sprayer), 8002 flat-fan nozzle at 300 kPa and a spray volume of 200 Lha-1. The plants were treated at 21 days (at the four- to six-true leaf stage) after planting. Chlorophyll fluorescence measurements were carried out on dark-adapted leaves at the same stages of development among pots. Fluorescence emissions were measured using a portable chlorophyll fluorometer (Handy-PEA), which emits light of 650 nm wavelength with an intensity of 3000 µmol photons m−2 s−1 for 10s. Leaves were dark adapted for a minimum of 30 min prior to measurement. The fluorescence measurements were taken 4 hours after spraying (HAS) for common lambsquarters and common purslane and again at 24, 48, 72 and 168 HAS. The Kautsky curves were visually examined for the effects of time and dose by the BIOLYZER program with OJIP steps as fix points. Results Discussion: The results showed that the parameters of measured had different sensitivity to the herbicides application, So that, four hours after desmedipham + phenmedipham + ethofumesate application on weeds mentioned, maximum quantum efficiency of PSII (Fv/Fm), did not show any change whereas the relative change in J stage fluorescence (Fvj) and the area between the curve and Kautsky (Area) Fm strongly reduced during this period, but chloridazon usage was not changes on Kautsky curve and their parameters during this period due to lower solubility, and sediment deposition in the sprayer tank mix. Common purslane was more affected by desmedipham + phenmedipham + ethofumesate application because of sponge leaves and stems while common lambsquarters had lesser sensitivity to both of herbicides application due to powdery and white cover over leaves and stems. Among chlorophyll fluorescence parameters measured, Fvj was appropriate parameter and quicker to detect the herbicides effects on both of experiments plants. Conclusion: In conclusion, various fluorescence parameters can be used to describe the shape and change of Kautsky curves in different plant species. In this paper we focused on common fluorescence parameters for two tested herbicides. The parameter Fv/Fm seems to be less sensitive to detecting changes than are Fvj and area. Since chlorophyll fluorescence parameters were affected after herbicide application immediately; therefore, it could be used as a practical tool for assessing the efficacy of herbicides in the early hours after spraying herbicides in the greenhouse and field experiments.

Measurement of chlorophyll fluorescence is noninvasive, highly sensitive, fast and easy way to give important information about the photosynthetic apparatus. Chlorophyll fluorescence parameters and Kautsky curves of wild oat and wild mustard sprayed by clodinafop and Dicamba+2, 4-D respectively was investigated at two green house experiments. The results indicated significant reduction at trend of Fv/Fm، Fvj and Area parameters five days after clodinafop spraying. The shapes of the Kautsky curves were affected by clodinafop five days after spraying. The maximum fluorescence (Fm) reduced significantly At 5 days after spraying. Chlorophyll fluorescence parameters revealed clodinafop efficiency one week before herbicide symptoms occurred. Chlorophyll fluorescence could be an alternative method to study herbicide efficacy compare to the classical method (measuring dry or fresh weight). At wild mustard the shape of the Kautsky curve at higher doses of Dicamba+2, 4-D (371.2 and 165.1 g ai./ha) was affected one day after spray. The Kautsky curve quenching after 1000 ms did not occur two days after spray at the recommended dose (371.2 g ai./ha) but its decay was observed at under recommended doses at both one and two days after spray. Finally although clodinafop and Dicamba+2, 4-D are not directly PSII inhibitor but they could change the Kautsky curves shape and form before revealing visual symptoms of these herbicides.

In order to investigate the germination characteristics and cardinal temperatures of biotype Alhaji pseudalhagi, A laboratory experiment was conducted randomized completely design with four replications of 25 seeds. Various constant temperatures 5, 8, 10, 15, 20, 25, 30, 35, 40, 45 and 50ºC were considered. The characteristics such as percentage of seed germination, rate of seed germination, the time of reaching 50% seed germination were recorded. In order to select best estimate of germination criteria based on three regression models namely: Five-parameters Beta(FPB), Intersected-lines(ISL) and Quadratic Polynomial(QPN) models. The effect of temperature on rate and percentage of germination was significant. The highest germination percentage(GP) was within the range of 20-35ºC while the highest germination rate(GR) occurred in 25ºC. Best model fit over the entire temperature range was obtained by the FPB model. Based on the regression between germination rate and temperature in biotype, the cardinal temperatures(Tbase, Topt and Tmax) were: (7.2-8.8), (27.5-30.6) and (42-50.5) °C, respectively.

Abstract To study the effect of competitive potential of corn (Zea mays), in competition with common lambsquarters (Chenopodium album) an experiment was conducted in 2006, at the farm of Agricultural Faculty of Ferdowsi University. In this experiment the effect of relative emergence time of common lambsquarters on single Cross 704 corn yield was studied in different densitis of the weed. The experimental design was split plot based on randomized completed block design with three replications. The emergence time at 3 levels (emergence of the weed 14 days earlier, 7 days earlier and simultaneously with corn) was considered as main plots and density of weed at 6 levels (0, 4, 8, 12, 16 and 20 plants m-2) as sub plots. The results showed a decrease in grain and biological yield of corn, as the emergence time of corn delayed in comparison with the emergence time of weed. The maximum yield reduction of 100 and 99% was observed respectively, in the earliest emergence time of common lambsquarters compared to corn and in the highest density of weed (20 plants m-2) where the corn plants were fully shaded by the weed canopy and no ear was produced. The yield loss of corn was higher when the earlier emergence time of weed was occurred in higher weed densities. based on the results of this research it can be concluded that the decrease of competitive potential of corn with increasing the relative emergence time of common lambsquarters was led to significant yield loss of corn crop. While the increase in weed density resulted in corn yield reduction, there was no difference in yield loss in high weed densities. Keywords: Biomass, Competition, Weed interference model, Yield loss

Abstract 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. Keywords: Germination percent, Germination rate, Germination uniformity, Radicle length

An experiment was carried out to evaluate the effects of planting depth and rhizome sizes on below ground growth of licorice (Glycyrrhiza glabra L.) at research glasshouse of Mashhad Unversity in 2001. Factorial experiment containing 2 factors of planting depth (10, 20 and 40‌cm) and rhizome sizes (1,2 and 3 buds or 4,7 and 10 gr) with two replications in completely randomized block design was employed. Development of different variables during growing season including root and mother rhizome dry weight were measured.The highest and the lowest root dry weight (RDW)have been seen in depth of 20 and 40 cm‌, respectively. About 100 days after planting (DAP), RDW increaseed very slowly but thenafter increased faster‌. Rhizome of any sizes in‌ 20 cm, gave the highest RDW‌. Three-bud rhizomes produced the highest RDW and 1-bud rhizome produced the lowest. Mother rhizome dry weight (MRDW) reduced untill 60 days after planting. After 75th day, MRDW has increased and all plants started to fill their mother rhizome and finally rhizome of depth 20 cm produced the highest dry weight. In 160 days after planting, mother rhizomes started to lose their weight‌. 1and 3 -bud mother rhizome produce the lowest and highest MRDW, respectively.

This study was conducted to investigate the effect of organic and bio-fertilizers on trifluralin durability.Herbicide persistence is an important consideration in crop production since residue levels of trifluralin herbicides can persist to the next growing season and may injure sensitive crops in the rotation. Residues of trifluralin persist in the soil for long periods. Extremely small amounts of resides can be devastating to some crops that are planted in the following year. Bioassay experirent is a common and cheaper experiment for herbicide residue detection in soil.In order to estimation of trifluraline halfe life in soila field experiment conducted as a factorial arrangement in completely randomized block designwith 3 replications. Experimental factor included two levels of trifluraline (EC %48) application rate480 and 960 g.Ha-1 a.i.). For determination of trifluralin residue, soil sampling was taken from 0 to 10 cm soil dept at 0, 3, 7, 15, 30, 60, 90 and 120 days after spraying. soil sampling and soil treatments were transferred to the greenhouse. The results of Bioassay experiment with sorghum plants showed decreasing trifluralin durability with the application of organic and biological fertilizer. The highest half life were observed (144 and 130 days), by using 480 g. a.i/ha related to shoot and root biomass and no fertilizer application respectively and the Least a half-life was in shoot biomass related to organic fertilizer treatment (18 and 19 days) and 480 and 960 g trifluralin active ingredient.