محمدکاظم رمضانی

Fresh and processed vegetables, in particular leafy vegetables are main sources of nitrate in the diet. The growth level and absence of contamination matters of these vegetables, particularly their cultivation in farm lands, in the suburb which may using sewage, is so critical. The primary target of this research is to determine nitrate concentration in the edible parts of radish, mint and parsley, and compare them with allowance limits and then introducing the most nitrate intaking herbs of the southern region of Tehran , in 2015.

Demanded products have been collected during three times sampling from Ahmadieh agricultural complex located in south of Tehran, in August and September of 2015, and the examinations have been repeated in three times for each sample. Eventually 90 samples were tested. The examinations carried out based on instruction provided by Iranian National Standard Organization

The results showed that mean concentration of nitrate in radish, radish leaves, mint leaves, mint roots, shoot mint, parsley leaf and parsley stem are respectively 19.02 ±1.342, 11.00±0.895, 17.70±1.369, 26.69±1.936, 20.82±1.261, 22.43±1.00 mg/kg, and also is indicative of the highest nitrate concentration is related to the mint and the lowest concentration in the radish, among all tested samples.
Discussion and

By considering vegetables watering with sewages in this region which could increase nitrate concentration in the products, Then it is necessary to check nitrate concentration of more samples to achieve an accurate result.

Metribuzin is one of the most common herbicides used in potato cultivation. This experiment was conducted to study the effect of soil characterstics and utilization history of metribuzin on its efficiency to redroot pigweed control as factorial on the base of randomized complete blocks design with three replications at Institue of Plant Protection in 2012. First factor was soil type in six levels (Hamedan with 15 years and without utilization history, Jiroft with 15 years and without utilization history, Isfahan with 2 years utilization history and Mashhad with 3 years utilization history) and second factor was different concentrations of metribuzin (0, 100, 300, 700, 1000 and 1500 g ai ha-1). Before cultivating redroot pigweed seed, the pots with mentioned soils were treated with metribuzin and harvesting was done four weeks after cultivating. Then, length and dry weight of shoot and root were measured and dose-response curves were drawn. The highest and lowest damage to redroot pigweed was observed in soils of Jiroft without utilization history and Hamedan with 15 years utilization history, respectively. In Jiroft soil with 15 years utilization history, shoot dry weight reductions were 15, 29, 45, 46 and 56 percent at concentrations of 0.1, 0.3, 0.7, 1 and 1.5 kg ai ha-1 of metribuzin, while in Hamedan soil with 15 years utilization history shoot dry weight reductions in the mentioned concentrations of metribuzin were 6, 11, 25, 31 and 36 percent, respectively. Results showed in different soils, increasing the concentration of herbicide resulted in a more favorable control of redroot, but increasing the amount of clay and organic matter, as well as increasing the history of consumption, affected the severity of the effects of metribuzin residues.

Bulb mites of genus Rhizoglyphus (Acari: Acaridae) have been identified as pest of many crops in storage, greenhouse, and field. The most important hosts are species of family Liliaceae (e.g. Allium spp.) Rhizoglyphus echinopus (Fumouze & Robin) (Astigmata: Acaridae) is one of the most important pest of gladiolus corms in Mahallat. The mites infest bulbs and corms by penetrating through the basal plate or outer skin layers. Bulb mites may establish in the inner layers, which makes control extremely difficult. Feeding wounds created by bulb mites provide entry sites for soil-borne fungal pathogens such as pythium, rhizoctonia and fusarium. Despite their economic importance and broad distribution, the control of R. echinopus remains in a state of confusion and needs a thorough evaluation. In addition, the field biology and ecology of this mite is not well studied, and methods for sampling, monitoring and assessment are limited. Management of bulb mites is complicated because of their short generation time, high reproductive potential, broad food niche, interactions with other pests and pathogens, and unique adaptations for dispersal. Historically, these pests have been controlled by synthetic acaricides and insecticides, which are now limited due to their resistance. Alternative control strategies, including cultural and biological control, have shown limited success, but need to be further developed and implemented. We evaluated the capacity of the soil-dwelling predatory mite, Hypoaspis (Geolaelaps) aculeifer (Canestrini) (Mesostigmata: Laelapidae), as well as disinfestations of corms to control attacking bulbs mite. The experiment was performed in 24 treatments and 3 replicates in randomized complete block design. Each plot was separated with plastic and its soil was sterilized by solarization. In addition, 30 gladiolus corms were cultivated in each plot. Disinfestations treatments (corms were soaked in poison solution for 25 minute) include: 1, 2 & 3- abamectin (0.4, 0.8, 1.2 ml/lit); 4, 5 & 6- ethion (1, 1.5, 2 ml/lit); 7, 8 & 9- fenazaquin (0.5, 1, 1.5 ml/lit); 10, 11 & 12- hot water (45°C for 25, 50 and 75 min); 13, 14 & 15- release of predator mite H. (Gaeolaelaps) aculeifer 10, 20 and 30 predator for every 100 Gladiolus bulb (previously infested with bulb mites); 16, 17 & 18- release of 100, 250 and 500 predator mites in square meter 15 days after planting; 19, 20 & 21- tap water as control treatments (30°C for 25, 50 and 75 min); 22- hot water (45°C for 25 min) and release 10 predator for every 100 gladiolus bulb; 23- hot water (45°C for 25 min) and release of 100 predator mites per square meter; 24- hot water (45°C for 25 min) and release 10 predator for every 100 gladiolus bulb and release of 100 predator mites per square meter 15 day after planting. Significant differences were found among treatments and with control (α= 0.5). In all cases, the population of predatory mites increased as long as bulb mite densities were not too low. Experiments in the greenhouse showed that in the absence of predatory mite, populations of the bulb mite, R. echinopus, on gladiolus corms increased, whereas population growth of bulb mite was slowed down as the predatory mite were released. The highest infestation severity was observed in treatments 19, 20 and 21 (control), while the lowest percentage of corms infestation were recorded in treatments 24, 23 and 22. The highest frequency of corms was produced in treatment 24, also the highest inflorescence length was found in treatments 13 and 24. The height length mean of gladiolus stem was observed in treatments 24, 23 and 13, respectively. The flowers in treatments 7, 14, 17 and 23 lived the greatest. The fastest germination rate was recorded in corms in treatments 24, 23, 22, 14, 15, 13 and 10, respectively. But the number of buds was statistically located in the same group and their differences were not significant. Based on the results and with respect to the gladiolus features, biological and integrated pest control methods could be recommended for reducing R. echinopus infestation.

This experiment was conducted to study the effect of metribuzin on cultivated oat in soils with different characteristics and utilization history as factorial on the base of randomized complete block design with three replications in Institue of Plant Protection in 2012. First factor was soil type in six levels (Hamedan with 15 years and without utilization history, Jiroft with 15 years and without utilization history, Isfahan with 2 years utilization hisrory and Mashhadwith 3 years utilization history) and second factor was different amounts of metribuzin in six levels (0, 0.1, 0.3, 0.7, 1 and 1.5 kg/ha). Three months before cultivating, the pots with mentioned soils were treated with metribuzin and were irrigated every three days. Then oat seeds was cultivated in pots and harvested after four weeks. Shoot length, root lenght, shoot wet weight and root wet weight was measured and dose- response curves were drawn. According to results, more oats were burned due to increase of herbicide amounts, but the effects of metribuzin residue were decreased by increase of amounts of clay, organic matter and utilization history. The highest and lowest phytotoxicity was observed in soils of Jiroft without utilization history and Hamedan with 15 years utilization history, respectively.

Potato is a cool-season vegetable that ranks with wheat and rice as one of the most important staple crops in the human diet around the world. Weed control is important in potato production management, because without doing it potato harvest would not be cost- effective. Metribuzin (4-amino-6-tert butyl-3-methylthio-1, 2, 4-triazin-5-one), a triazine, is used as a selective herbicides for control of annuals grasses and broadleaf weeds inpotato. Its herbicide efficiency and its relatively low toxicity are such that it is widely used around the world. Replacing metribuzin with other herbicide that have the greatest effect on weed control in potato seems unlikely. The persistence of metribuzin in soil is defined as the period or extension of time in which it remains active. Knowing the case of herbicides is particularly important because, on one hand, it determines the period of time in which weeds can be controlled, and on the other, it is related to the later phytotoxic effects which can damage the subsequent crops. In order to understand about affiance of this herbicide in potato fields, researches on metribuzin toxicity in common lamb’squarters in soils with different utilizations are essential.
Material and This experiment was conducted to study the effect of soil characteristics and utilization history of metribuzin on its efficiency to common lamb’squarters control as a factorial on the base of randomized complete blocks design with three replications in green house of Institue of Plant Protection in 2012. First factor was soil type in six levels (Hamedan with 15 years and without utilization history, Jiroft with 15 years and without utilization history, Isfahan with 2 years utilization history and Mashhad with 3 years utilization history) and second factor was concentration of metribuzin in six levels (included 0, 100, 300, 700 and 1000 g ai h-1). Soil samples were collected from 0-15 cm depth. Before cultivating, the pots with mentioned soils were treated with metribuzin. Each sample was thoroughly mixed to allow a homogeneous distribution. Non-sprayed samples were used as controls. Common lamb’squarters seeds were planted in pots and the soil in each pot was watered as mist. After emergence, the seedlings were thinned to two per pot. Harvesting weeds were done four weeks after sowing. Then, dry weight and the length of shoot and root were measured. All data were subjected to analysis of variance and means were compared at the 5% level of significance. The classical bioassay, often used to quantify the amount of herbicide in soil, employs a single “standard” dose-response curve. This standard curve show the plant response to different herbicide concentrations and report information of different concepts related to herbicide efficacy, such as selectivity, tolerance and resistance. A typical dose-response curve is sigmoid in shape. One example of such a curve is the loglogistic curve. The data were expressed as a percentage of the untreated control and dose- response curves were drawn.
According to results, more common lamb’squarters was controlled due to increase of herbicide dose. But the effects of metribuzin residue were decreased by increase of amounts of clay, organic matter and utilization history. The amount of herbicide required to reduce the growth of weed by 50% (GR₅₀) when compared with the control was determined for each soil. In the soils with higher organic matter GR₅₀ were increased. The highest and lowest damage to common lamb’squarters was observed in soils of Jiroft without utilization history and Hamedan with 15 years utilization history, respectively So in the soil with long utilization history of metribuzin, common lamb’squarters control was greatly reduced due to the presence of microorganisms adapted to the herbicide and use of it to supply energy. The breakdown of herbicides by soil organisms known as microbes accounts for a large portion of herbicide degradation in soil. Certain bacteria, fungi, and algae use herbicide as a food source. Microbes are herbicide-specific and their population in the soil is related to the amount of herbicide can lead to increased microbe populations and a shorter duration of effective weed control. Organic matter provides excellent habitat for microbes. The adsorption degree of this herbicide is positively correlated with organic matter content and negatively with their persistence. In these situations for controlling this weed higher concentration of metribuzin must be used.

In this research، we used a new model to determine the risk of 58 current use insecticides and acaricides، mosly applied for agricultural purpuses. The OECD POV & LRTP Screening model used to calculate the environmental risk of pesticides using indices of overall persistence (POV)، long-range transport potential (LRTP)، and intake fraction (IF) was calculated using USES-LCA 2. 0 & Simple Box 3. 0. Integrating these parameters with acceptable daily intake (ADI)، LD50 bee، LD50 mice and LC50 fish made possible the risk assessment of 58 of current used pesticides. Screening and raking results showed that of 13 acaricides، 38% calssified with low، 38% with medium and 24% with high risk level. Of 45 studied insecticides 31. 7% showed low risk، 26. 9% showed medium، 23. 8% with high and 15. 8% showed very high risk. Risk assessment based on the most important crop/fruits demonstrated that pome and stone fruits 42. 9%، pistachio 41. 2%، citruses 35%، soybean 10%، sugarbeet 29. 4%، vegetables 17. 6%، cotton 26. 3% and cereal (wheat and rice) 31% of insecticides and acaricides are classified with low risk. Therefore، according to the results of the current research، it is clear that risk management of insecticides and acaricides in Iran toward reducing risk level is possible.

Pesticides are extensively used to protect crops and to prevent disease. The use of these compounds in modern agricultural systems is indispensable. It is estimated that a small portion of applied pesticides gets to the target pests and most of them enter various compartments of the environment. Pesticides losses from areas of application can be a threat to the different organisms in ecosystems as well as human health. Increasing concern about the pesticides has been emerged with the role of pesticides in disrupting endocrine systems of mammals. The endocrine system acts a significant role in normal growth and development and in reproduction. Once released to the environment, pesticides may be affected by various processes including abiotic and biotic degradation, adsorption and transfer to the water systems as well as air and food. The relative importance of each of these processes is related to physico-chemical nature of pesticide and climate conditions. Environmental changes can also influence the fate, persistence, and toxicity of pesticide and increase or decrease their side effects on organisms in the environment. Due to the high cost of pesticides trace in different matrices of the environment, it has been recently taken into consideration some indicators for quantifying the risks of pesticides for the environment and human health. These models are able to investigate the trend of pesticides risk in time and assess the ecosystem health. The present paper is an overview of the different factors affecting the behavior of pesticides in the environment as well as a critical review of different indicators for the assessment of pesticides risks. We also explore the extent to which these indicators can used in Iran with regards to the lack of data and advantage/disadvantage of the indicators will be presented.

Crop residue burning is applied in agricultural systems to remove extra residues before or after harvest. Although, there are some benefits of crop residue burning, but soils amended with crop residue ashes would obviously be increased herbicide persistence, and change desorption, and bioavailability of herbicides in soils crop residues have burned. It may also limit the access of microorganisms to the herbicides and therefore, prolonged carryover effect of their residues on rotational crops, resulting in cost burden for farmers due to the enhancement of sorption and the decrease of herbicides efficacy. The behavior of herbicides (persistence and movement), uptake by plants, and efficacy of herbicides in soil for control of weeds is governed by a variety of physical, chemical, and biological processes that are often complex and dynamic. The key process includes sorption–desorption, volatilization, and chemical and biological degradation, transport from soils into water, is directly controlled by these processes. Ashes arising from the burning of crop residues may be an important factor leading to changes in soil properties with contact time resulting in increased immobilization and sorption of herbicides. This paper highlights some key factors affecting the behavior of pesticides in the soil, in particular, understanding the effects of ashes on fate and efficacy of herbicides especially dealing with agronomic and crop residue burning.

Herbicides are one of the crucial options in weed management in most agricultural production systems of world. The introduction of the new herbicide families has had many benefits including very low application rates and low mammalian toxicity. As these herbicides can also be absorbed through the foliage or roots and have high mobility in plants, leading to broad-spectrum control of weeds and having soil residual persistence that gives some control of emerging weeds after application. That is why the use of these herbicide products was rapidly accepted by agricultural producers for crop production. Although, this aspect of the new herbicides is useful for control of emerging weed during the growth season, but the herbicides residues can persist to the next season(s) and damage subsequent crops. A wide range of interrelated factors impact the fate of herbicides in soil. Understanding these factors and processes can make possible the best weed control as well as reducing the potential for injury to non-target crops. Pertinent environmental conditions consist of the chemical, physical and biological characteristics of the soil to which the pesticides are used and climatic features such as rainfall, wind, temperature and light regime. These factors particularly moisture and temperature are two key factors that determine the extent of sorption and degradation of herbicides in the soil matrix. Various mechanisms including phtodegradation, volatilization, leaching, sorption and degradation are determinant processes of herbicide behavior in the environment. The present paper is an overview of the most important processes namely sorption and degradation of herbicides in soil, the environmental factors and herbicides nature which affect the behavior of these chemical in the soil.

In orther to determine the critical period for weed control in the Chitti bean (Phaseolus vulgaris) line KS-21467 a field study was conducted at the Bean Research Station of Khomein by a randomized completele block design in 2001 and 2002. The treatments included weed free and weed infested period until 20, 28, 36 and 44 days after planting (DAP) with two weed free and weedy checks. The results indicated that the critical period at 5% allowable yield loss was 20-53 DAP (between first-trifoliate and flowering stages) in 2001 and 35-51 DAP ( between blossom and flowering stages) in 2002. Weed dry weight decreased averaglly 81% in weed-free period until 44 DAP compared to the weedy check. Yeild decreased averaglly 63% in weedy check compared to the weed free check. Weed competition increased the height of bean, wherease 100-seed weights and the number of seeds per pod were not substantially affected. There was a negative and significant correlation of weed dry weight with the number of pods per plant, the number of seeds per plant and yeild.