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Allelopathy is how one plant, by producing chemical compounds, affects another plant, either in a harmful or beneficial way, directly or indirectly (Prati and Bossdorf, 2004). Allelopathic phenomena have existed since the distant past and there are estimates in connection with weed control using this material. Pigweed (Amaranthus retroflexus) is one of the most important weeds (McNaughton et al., 2005). This study aimed to control pigweed using allelopathic substances (alcohol and aqueous extracts) of five species of poisonous houseplants.
This experiment was conducted as a factorial in a completely randomized design at the Agricultural Faculty, Tarbiat Modarres University in 2014. Experimental factors included five poisonous houseplants (oleander (Nerium oleanderDieffenbachia amoena, Caladium candidum, Lilium ledebouri and Chrysanthemum indicum) at three concentrations of 5%, 15% and 25% of aqueous and alcohol extract, as well as their control. To evaluate the allelopathic potential of different concentrations in the alcoholic and aqueous phases of five poisonous species, root and shoot length, maximum germination, germination rate, uniformity of germination, germination percentage, seedling length and vigor index were compared. A glasshouse study was conducted to evaluate the effect of the potential of allelopathic extractions on the growth and physiological parameters such as the fresh and dry weight of leaves, stems and inflorescence, and the leaf area of redroot pigweed.
Results showed that the longest roots and shoots, maximum germination, germination rate, germination uniformity, germination percentage, seedling length and vigor index were observed in the treatment without extract, while the different extract treatments caused a sharp decline in trait values. The highest leaf dry weight was observed in a foliar application of 5% aqueous extract of diphenhydramine. The highest dry weight of inflorescences was seen in an alcoholic extract treatment that was applied to the soil with 5% of the Lilium extract. The highest dry and fresh weight of stem was observed in caladium aqueous extract with 5% of the extract applied to the soil. The highest leaf area occurred with a foliar application of 5% caladium extract. The highest fresh weight of leaf and inflorescences was obtained in aqueous soil treatment of 5% oleander extract. Previous studies showed that the effect of plants from the cabbage family on canola seed germination and seedling length are significant. The results showed that canola had maximum and cress minimum potential of inhibition. However there was no significant difference in their effects on root growth (Rezaei-Nodehi et al., 2003). There were significant differences between ornamental plants in terms of germination percentage and seedling length. Generally, the higher concentration of the extract decreased the traits values which can be increased by increasing the amount and toxicity of allelochemicals. Also, it can be deduced that allelochemicals may be selective. This point is emphasized in the topic of weed control. On the other hand, root growth in redroot pigweed was inhibited more than shoot growth. Compared to the aqueous extracts, alcoholic extracts were more effective in decreasing the values of traits in this experiment.
The results of this research confirm the previous reports that the growth of the root was more sensitive than the shoot and all plant traits can be affected negatively by allelopathic substances and their growth reduced.

Having the richest plants biodiversity, Hyrcanian natural mixed-beech forests contribute to the huge carbon pool in the different soil layers. This research aims to develop modeling soil carbon sequestration in terms of the plant biodiversity indices to manage soil carbon stock with respect to trend of sustainability, fertility, carbon cycle, and planning to face with climate change in local/ regional scales. After measuring plants biodiversity indices and soil carbon factor over the field operations, simple and multiple linear regressions as well as curve estimation regression were applied in the process of modeling. According to Adj.R2, SEE and AIC, simple and multiple linear regressions had no considerable accuracy (AICmin = 힝.74). Analysis of non-linear models showed that model S including index of species dominance belonging to herbal coverage was the best predictor with the least error and highest certainty (AICmin= -171.23) to estimate soil carbon pool in the studied forests. In the following, the results showed that although the log-transformed models with increasing the parameters and adding the correlated explanatory variables were valid (VIF

Quality properties of groundwater is one of the major components which can used for water resources management. In this study, spatial variability of groundwater quality for drinking uses
(Schoeller standards) and agricultural uses (Wilcox standards) was investigated during 1387-1392.In this research, we use information of 24 observation wells in Fasa plain, to investigate the spatial variability of water quality parameters for different category by using geostatistics technique in GIS software and associated areas of different classof water quality were also determined. Afterwards, the change in the area by using parametric (linear regression) and non-parametric (Spearman) statistical tests for determined period was evaluated. The results showed that the areas with suitable class for drinking and agricultural uses based on the both statistical methods were decreased, while the areas with unsuitable class were increased. The categories of drinking water quality evaluated by spatial variability of the study area fall under unsuitable class, Bad class and temporarily acceptable class which these areas have been increased and are not significant at 95% level. The categories of agricultural water quality evaluated by spatial variability of the study area fall under good class, average class and bad class which the areas with average quality class have been decreased and the areas with bad quality class have been increased,these variables are significant at 95% level based on the both statistical methods.

Alfalfa (Medicago sativa L.) is the most important forage legume worldwide and, due to its slow growth in the initial vegetation stages, may become highly infested with weeds (Wilson and Burgener, 2009). Thus, methods of sowing and alfalfa development have a significant effect on the crop establishment (Booth et al. 2003). Reliable methods for alfalfa establishment are important for productive and long-lived stands. Sowing a companion crop with alfalfa can help prevent erosion, reduce weed pressure and provide a forage crop before the alfalfa is ready for cutting (Tan and Serin, 2004a). A companion crop is a fast growing annual crop that grows quickly enough to overcome weeds and provides a cash return in the establishment year. The objective of this study was to investigate the impact of different alfalfa and companion crop densities on alfalfa forage yield and weed control in establishment year.
In order to study the effect of a barley (Hordeum vulgare L.) companion crop on alfalfa weed density and biomass, a field experiment was conducted in 2013-2014 in the research fields of the Plant Protection Research Institute, Karaj. The experiment was established as randomized complete block design with a factorial arrangement of treatments and 4 replications. Two factors including, seeding rates of alfalfa at two levels (30 and 45 kg/ha) and seeding rates of barley at 6 levels (0, 30, 60, 90, 120 and 150 kg /ha) were considered. Traits measured in this experiment included hay yield, weed density and biomass in the first cut and hay yield and weed biomass (if any) in second, third and fourth cuts.
Results showed that increases in alfalfa seeding rates from 30 to 45 kg/ha, significantly increased annual hay yield (8.6%). Increases of barley companion crop seeding rates also caused a significant increase in annual hay yield in comparison with pure alfalfa, as greatest hay yield (80.57) was observed in 60 kg seeding rates. Weed density and biomass of first cut was influenced by additive intercropping treatments of alfalfa and barley. Use of barley as companion crop, in addition to reducing weed density and biomass, suppressed alfalfa plant growth and reduced the percentage of alfalfa in the first cut hay yield. Residual effects of barley were seen in the subsequent cut, so that different densities of barley reduced weed biomass compared to the control in the second cut. The results of this study showed that use of barley as companion crop can play significant role in reducing dependence on herbicides and increase forage quality. Based on results from the first year, the seeding rates of 45 and 60 kg ha-1for mixed cropping of alfalfa and barley respectively, in addition to increases forage production, can control weeds effectively.
The results of this study indicate that barley reduced both weed competition and alfalfa growth, but increased total hay yields in the establishment year. The residual effects of the companion crop on weed suppression continued in the second cut. In most cases, the 45 kg/ha alfalfa seeding rate was superior. Sowing the barley at a higher seeding rate of more than 60 kg/ha appeared to depress initial growth of alfalfa in the seeding year, especially at the first harvest. The results showed that alfalfa can be successfully established with a companion crop. Based on the first year results and in order to achieve the best result, it is suggested that alfalfa and the barley companion crop be sown at the 45 and 60 seeding rate respectively.

Valuation and quantifying of different services for agro-ecosystems is one of the main effective factors for increased attention to these services and for adopting suitable approaches to sustainability of these services. In fact, economic valuation reflects the value of some ecosystem functions, goods and services, and helps social and economic planners and managers to plan the conservation and sustainable exploitation of resources. A solution for achieving sustainability on farms is the use of the natural services in agricultural lands through the replacement of off-farm inputs such as pesticides and chemical fertilizers.
In the study, the value of agro-ecosystem services was evaluated under two different management systems, including conventional and organic for wheat and potato crops in Fariman city. The agroecosystem services studied included primary and secondary production as market services and pest control, soil production, carbon sequestration, supply of nutrients from the soil and soil fertility as non-market services. The main products included the two products (tubers and seeds for cultivation and harvest-to-send to the market in the following year), which farmers purchase and sell. The economic value of secondary production was the price of wheat and potato residual on the farm and this residual was considered as a secondary production. Other ecosystem services included non-market values. The market and non-market value of the ecosystem services in conventional and organic farms were calculated. These values were evaluated according to three different scenarios on the total acreage of wheat (10000 hectares) and potato (800 hectares) in the Fariman region. In this scenario it was assumed that 10, 25 and 50 percent of the total area of conventional wheat and potato farms would be replaces by an organic system. Finally, the differences between the scenarios were compared with the condition where the total area was under the conventional management.
The results showed the conventional potato system had a higher market value than the organic system, but the value of non-market services in the conventional was less than in the organic. Market and non-market values for wheat organic farms was higher than conventional farms, so that the total value of ecosystem services in organic farms was equal to 9.75 million RS ha-1 year-1 and this value for conventional systems gained about 7.84 million RS ha-1 year-1. The results of the evaluated scenarios illustrated that the value of non-market services increased with an increasing cultivated area of potato and wheat in the Fariman region so that, when 50% from total cultivated area of potato and wheat will be managed as organic, the total non-market value will be increased by 861 million RS year-1 and 6998 million RS year-1, respectively. Other studies also showed that ecosystem services, especially non-market services, have more value in organic agriculture than in conventional and intensive agriculture (Takatsuka et al., 2005). Sandhu et al. (2008) showed that the value of ecosystem services were 4600 and 3600 US $ per hectare per year in organic and conventional systems, respectively. Grandy and Robertson (2007) indicated that the total value of ecosystem services in organic agriculture is more than in conventional agriculture.
This study showed that organic management systems of potato and wheat farms provide more ecosystem services, especially non-market services, in comparison with conventional systems. However, in some cases, loss of yield and market value reduced the total value of organic agricultural services, but it should be noted that the movement towards organic and sustainable farming provides both -market services as well as market services such as environmental protection and healthy food production.

Energy analysis of agricultural ecosystem is essential for sustainable production. The relation between agriculture and energy is very close. Agriculture is an energy consumer and the energy supplier. Agriculture’s use of energy is recognized in three external inputs: labor, machines, and fertilizers (Connor et al., 2011). Significant gains in energy efficiency were arisen in agriculture following the phenomenal increase in energy prices in the 1970s. Greater use of diesel motors, larger tractors, using conservation tillage methods and optimized fertilizer use efficiency were the main causes (Ozkan et al., 2004). Safa & Samarasinghe (2013) were reported that fuel consumption in tillage and harvesting was more than other operations in wheat fields of Canterbury, New Zealand. Effective application of agricultural techniques and efficient use of support inputs can minimize environmental problems and in consequence promote sustainable agricultural intensification. In this study, the energy flow investigated in irrigated and rain-fed wheat cropping systems under two tillage and no-tillage methods in the Shahrekourd city, during 2013.
The study was carried out in the Sharekourd city (Chaharmahal Bakhteyari province). This region is located within 32º 20' and 32º 21' Lat. N, 50º 48' and 50º 50' Lon. E. Data were collected from 40 farmers with questionnaire method. In this study, a randomized complete design with four scenarios (rain-fed and irrigated farming with tillage and no-tillage systems) was used, that 10 farms were considered as a replication in each scenario. All data detail information on the questionnaire were averaged and arranged. First, all inputs and outputs of wheat production were determined, quantified and entered into Microsoft Excel spreadsheets, and then transformed into energy units and expressed in MJ.ha-1. Based on the total energy equivalents of the inputs and output and the energy use efficiency (energy ratio), net energy, energy productivity and specific energy were calculated. The input energy was divided into direct, indirect, renewable and non-renewable forms. Indirect energy included energy embodied in seed, fertilizers, chemicals, machinery; while direct energy covered human labor, water for irrigation, electricity and diesel fuel were used in the wheat production. The LSD test (P≤0.05) was used to compare means between all scenarios.
The results of data analysis indicated that maximum input energy was about 29,586 MJ.ha-1 in the irrigated fields under tillage and maximum output energy was about 70,743 MJ.ha-1 in the irrigated fields under no-till. In this study, the highest and lowest energy efficiency were obtained in irrigated system under no-tillage (2.43 in seed) and rain-fed system under tillage (1.03 in seed), respectively. The greatest contribution from total energy belonged to energy of nitrogen fertilizer (9,429 MJ.ha-1 in no-tillage and 1,092 MJ.ha-1 in tillage systems) and irrigation (8,323 MJ.ha-1 in no-tillage and 5,117 MJ.ha-1 in tillage systems) in irrigated cropping system and nitrogen fertilizer (8,529 MJ.ha-1 in no-tillage and 7,220 MJ.ha-1 in tillage systems) and seed (4,367 MJ.ha-1 in no-tillage and 2,412 MJ.ha-1 in tillage systems) in rain-fedfarming system. Therefore, it is necessary to focus more on nitrogen fertilizer consumption than the other factors to effectively reduce energy consumption in wheat cropping. In addition, the no-tillage system had high indirect and non-renewable energy forms in both wheat cropping systems. The high ratio of non-renewable energy in the total used energy inputs cause negative effects on the sustainability in agroecosystems.
Generally, irrigated cropping system under no-tillage method was the best condition for wheat production in Shahrekourdcity. The results revealed that there was a huge potential toimproveenergy efficiency of wheat production in this region. Furthermore, toreducenon-renewable energy use in the studied region, we recommended the use of chemical fertilizer specially nitrogen reduce by appropriate management of fertilizer, use of legume in crop rotation, use of green manure, organic fertilizer and manure.
Acknowledgements
We are grateful to Agriculture Service Centers of Shahrekourd and Gorgan University of Agricultural Sciences and Natural Resources (GUASNR).

Drought stress reduces plant growth by affecting various physiological and biochemical processes, such as photosynthesis, respiration, translocation, ion uptake, carbohydrates, nutrient metabolism and growth promoters.
Garlic (Allium sativum L.) is an annual bulb crop that has been cultivated since ancient times and was used as a spice and condiment for many centuries. Garlic is an important plant because of its pharmaceutical properties. The optimum yield of this bulb crop depends on well-managed irrigation, fertilization and cultivation practices. In the final and middle stages of growth, garlic is sensitive to water stress and low irrigation is unsuitable in these stages.
This experiment was established to study the influence of drought stress and planting density on yield and its components and the non-enzymatic anti-oxidant content of two different garlic ecotypes.
This study was conducted in 2011-2012 in a farmland at the south east of Semnan city. The experimental layout was a split-plot factorial with a randomized complete block design with three replications.
The treatments were comprised of three factors: irrigation rates (60%, 80% and 100% of estimated crop evapotranspiration (ETC)) as the main plot and the factorial combination of three levels of planting density (30, 40 and 50 plants.m-2) and two ecotypes (Tabas and Toroud) as the sub-plots.
To estimate the crop water requirement, different meteorological parameters were collected from Semnan weather station and were used based on FAO-56 water irrigation calculation instructions.
After harvesting, ten garlic plants were sampled randomly in each plot and bulb yield components were measured. To calculate the leaves anti-oxidant content, DPPH method was used. The statistical significances of mean values were assessed by analysis of variance and LSD tests at p≤0.05. All calculations were performed using SAS and Mstat-C softwares.
Drought stress decreased bulb yield and dry matter percentage significantly.
Planting density had significant effects on bulb yield and the yield of planting density of 50 plants m-2 were significantly higher than two other densities.
The interaction of drought stress and ecotype factors affected the dry matter percentage.
Drought stress decreased fresh and dry weight, length of bulbs and the bulb diameter significantly.
Drought stress decreased fresh and dry weight, diameter, length and number of cloves significantly as well.
Drought stress is an important limiting factor at the initial phase of plant growth and establishment. It affects both elongation and expansion growth (Shao et al., 2008).
Fresh and dry weight and length of cloves were significantly higher in Toroud ecotype. In contrast, the number of cloves in the bulb was significantly higher in Tabas.
Studying the correlation coefficients showed that the bulb yield per unit area was significantly and positively correlated with diameter, weight and length of cloves and bulbs and also the dry matter percentage at P≤0.001. The maximum correlation belonged to yield at the unit area and weight of the bulb (r=0.72). In other words, any bulb-weight-increasing factor did have the highest effect on increasing the yield per unit area as well.
Drought stress, increased leaf non-enzymatic anti-oxidant significantly.
Anti-oxidants plays significant roles in ROS scavenging and influences cellular ROS balance. Activation of antioxidant system helps the plants to tolerate stress form induced damage.
The effect of ecotype was significant on anti-oxidant content and the value were significantly higher in Toroud ecotype. Toroud ecotype showed resisting reactions against higher levels of drought stress by increasing the non-enzymatic anti-oxidant content and created tolerating mechanisms versus stress.
Drought stress reduced yield and yield parameters and increased non-enzymatic anti-oxidant content of garlic. The increment of anti-oxidant content showed the tolerance of garlic to drought stress. The maximum bulb yield was obtained at the highest planting density.

Recently, the planting of narrow lead cover crops has had a noteworthy effect in reducing the use of herbicides. This experiment was carried out during 2011-2012 at the Natural Resources research station in Samian (Ardabil Province) as a factorial study in a randomized complete block design with 3 replications. The first factor included three types of cover crops, rye (Secale cereal), barley (Hordeum vulgare) and wheat (Triticum aestivum) with two controls: (1) without cover crops, with complete weeding and (2) without cover crops and without weeding. The second factor involved management at two levels (live mulch and non-living mulch) and the third factor was with two levels of cover crop planting date (synchronic with planting sunflower and 45 days after planting sunflower). Results showed that the effect of cover crops was significant on sunflower seed yield, protein percent and yield, shoot dry weight, head dry weight and height. The highest seed yield was obtained at control 1 (4053.3 kg ha-1) and in wheat and rye cover crop traits were 3916.7 and 3798.3 kg ha-1, respectively. The highest protein (42.51%) and protein yield percentages (1.69 t ha-1) were observed in control 1 (without cover crops, with complete weeding). Also, the maximum height (173.73 cm) was related to synchronic planting of cover crops with sunflower. The highest single seed weight mean was observed in live mulch management in synchronic planting (0.087 g m-2) and in dead mulch management at 45 days after planting (0.089 g m-2). The interaction of cover crops and planting date had significant effects on weed density and dry weight so that the minimum density and total dry weight of weeds were observed in the cover crops of rye, wheat, barley respectively and at the same planting date. The maximum density and dry weight of weeds were observed in control 2 (without cover crop, without weeding).

Cover crops are an effective tool in the non- chemical weed management in sustainable agriculture. In order to evaluate the effect of type and time planting of cover crops on weed control in tomato، a factorial experiment was established using a randomized complete block design with three replications at 2013 on personal farm located about 65 kilometers from Shiraz province. The factors were included the type of cover crop at four levels (rye، red clover، rapeseed and control (no mulch)) and time of planting in three levels (one month before tomato transplanting، at the same time and one month after transplanting). The results showed that the type and time of planting of cover crops had a significant effect on the weed density and weed dry weight and tomato yield. Planting cover crops decreased weed density up to 35% and the weed dry weight of 67% compared with control. Also، cover crops reduced density of Convolvulus arvensis، Portulaca oleraceae and Echinochloa crus-galli as 8، 4 and 6 times compared with control. Tomato yield increased 60/42% with cover crop. The results showed that cover crops are appropriate tool for weed management in sustainable agricultural systems and can be used in integrated weed management.

Nowadays, planting cover crops to reduce herbicide use is advised. An experiment was conducted at Ardebil Agricultural and Natural Resources Research Station (at Samian) in the spring of 2012. Experimental design was a factorial arrangement based on a randomized complete block (RCBD) with three replications. The first factor was cover crop types including rye, hairy vetch, berseem clover, green pea and weed control treatment (no cover crop) and the second factor consisted of three levels of management including living mulch, bottom cutting mulch and cover crop topping from 20-30 cm height. Cover crops were planted between rows of KSC400 corn cultivar. The results showed that rye, hairy vetch and berseem clover and green pea could reduce the total density of weeds compared to the control by 76, 68, 65 and 55 percent respectively. The lowest weed biomass was in rye and vetch treatments with an average of 52.94 and 68.34 g m-2 respectively. The highest forage yield was 57500 kg ha-1 in weeding treatments and then 56450 kg ha-1 in hairy vetch. There was no significant difference between other cover crops. The results also showed that the living mulch management was the best in comparison to others with 52700 kg ha-1 forage yield production. The lowest yield was achieved in the control treatment without a cover crop, with 35000 kg ha-1 forage production. The results also showed that the highest fresh ear weight (32600 kg ha-1) was in the weed-free treatment, and then in hairy vetch at 31000 kg ha-1. The highest ear length (39 cm) was in the weed-free treatment too where there was no significant difference between hairy vetch and clover. The lowest ear length (28 cm) was in the control without any cover crop.

Weed biocontrol by using Eriophid mites could be a safe and efficient strategy. In order to find an ecological non-chemical approach for controlling of weeds, and studying the possibility of using Eriophyid mites, field surveys were conducted in Razavi Khorasan and North Khorasan Provinces during spring 2010. Collecting of mites was carried out at all of the vegetative and reproductive stages of these target weeds. Twenty plants of each species were selected and transferred to laboratory after each sampling. The results showed that gall mite (Aceria drabae Nalepa 1890) (Acarina: Eriophyidae) is a suitable biocontrol agent for controlling hoary cress. It decreased shoot growth and seed number. Gall mite (Aceria chondrillae (G. Can.)) (Acarina: Eriophyidae) was able to prevent seed set and reproductive buds of rush skeletonweed, it could be considered as a potential promising biocontrol agent. Since, Eriophyid mites were able to reduce vegetative and reproductive characteristics of studied weed species, these could be considered as a potential promising biological control agents for using in ecological agriculture.

In order to study of crop rotation and weed management methods effects on weed population، a 5-yr experiment was conducted from 1384 at field research of plant protection research institute، Karaj، Iran. The experimental treatments were crop rotation (including: sugar beet-sugar beet and sugar beet-wheat) and weed management method (including: chemical، chemical+ mechanical and hand weeding) that arranged in factorial experiments based a randomized complete block design with 4 replications. In contrast with sugar beet- wheat treatment، results indicated that annual and perennial weed populations increased in the end of rotational period in mono-culture system. Annual weed population also decreased in integrated weed management plots but it had no effect on perennials. Result suggested that the weed seed community in a sugar beet- wheat rotational system differs in structure and composition from communities associated with continuous sugar beet system، which in the end of 5 years experiment، percentage of bindweed and Johnson grass seeds in soil (in compare with knotweed and amaranth) were fewer in rotational treatments and they distributed in layers deeper than in 0-10 (cm) layer of soil.

Identifying indicator species and plant functional trait facilitate predicting ecological characteristics of arid and semi-arid ecosystems and help managers to introduce appropriate plant species in order to rangeland management reclamation. This study focused on indicator species related to three grazing regimes (exclosure, moderate and high grazing intensity) in steppic rangelands of Borojen, Chaharmahal and Bakhtiari province. Sampling was according to a random-systematic method in which the cover of plant species estimated within 10 plots established along three transects in each grazing regime. Plant traits include growth forms (annual forb and grass, perennial forb and grass and shrub), life form (Terophytes, hemi- cryptophytes, cryptophytes, chamaphytes and phanerophytes), vegetation structure (Rosette, semi-rosette and erect), plant palatability (Class I, II and III) and plant height. In order to identify indicator species and examine of changes in plant community composition, we used indicator species analysis and non-metric multidimensional scaling. Results of indicator species analysis showed that 16, 8 and 8 indicator species were identified for exclosure, moderate and high grazing intensity regimes, respectively. There were also indicator functional traits for each grazing regime including hemi-cryptophytes, cryptophytes, perennial grass and palatable plant class I was related to exclosure, annual forb, perennial grass and erect forb related to moderate grazing and finally annual grass, therophytes, rosette and palatability class III related to high grazing intensity. Results indicate that grazing was responsible for changes in indicator species and finally resulted in a significant shift in community wide trait composition. As a consequence grazing regimes can be identified using indicator species, however, several species and functional traits indicator should be into account.