نشریه بوم شناسی کشاورزی
سال هشتم شماره 4 (زمستان 1395)

Intercropping is an old and widespread practice used in low input cropping systems in many areas of the world. In fact, intercropping is claimed to be one of the most significant cropping techniques in sustainable agriculture, and many researches and reviews attribute its utilization to the number of environmental benefits from promoting land biodiversity to diversifying agricultural outcome. Furthermore, it is thought to be a useful mean for minimizing the risks of agricultural production in many environments, including those typical of under-developed or marginal areas. Intercropping systems, especially those employing non legumes with legumes, have several major advantages such as higher total yield and better land use efficiency (Dhima et al., 2007), yield stability of the cropping system (Lithourgidis et al., 2007), better utilization of light, water, and nutrients (Javanmard et al., 2009), improved soil conservation and better control of pests and weeds. Intercrops including of legume are common in agriculture ecosystems, but now are rarely used in developed countries, except for certain intercropping systems used for animal feed. Intercrops can use the available environmental resources more efficiently and thus result in higher yields than mono crops. The reasons for the higher yield in such systems is that the intercropped species do not compete for exactly the same growth resource niche and thereby tend to use the available resources in a complementary way. In particular, non legumes seem to be more competitive for soil inorganic nitrogen (N) than legumes due to faster and deeper root growth and higher demand in N. Consequently, the legumes usually increase their reliance on symbiotic N2 fixation. In the present study, it was aimed to assess the production of biomass, yield, grain quality and land equivalent ratio (LER) in plant society of sunflower/bean.
This experiment was carried out with aim of evaluation of the yield, seed quality and LER in sunflower and bean intercropping based on a randomized complete block design with three replications and nine treatments at Bu-Ali Sina University during growing season 2010-2011. Additive intercropping of 25, 50, 75 and 100% bean with sunflower, replacement intercropping of 25:75, 50:50 and 75:25 (bean:sunflower) and monoculture of sunflower and bean were the experimental treatments. SAS procedures and programs were used for analysis of variance (ANOVA) calculations. The significance of the treatment impact was determined using F-test by measuring significant differences between the means of the treatments, and least significant differences (LSD) were estimated at the probability level of 5%.
Results indicated that with shifting from sole cropping toward intercropping, seed weight, kernel weight, kernel to seed ratio, seed yield, biological yield, harvest index (HI), oil percentage and yield and protein yield decreased significantly, but protein percentage and SPAD reading increased. The highest sunflower seed yield (353 g.m-2) without significant difference with additive intercropping of 50% bean with sunflower observed at sole cropping of sunflower. Except seed number per pod and protein percentage, the effect of treatments was significant on pod number per plant, 100- seeds weight, seed yield, biological yield, harvest index, yield of protein and SPAD reading of bean. Maximum yield of bean recorded in bean sole cropping treatment. In all intercropping treatments, the value of LER was more than one and the value of competition index (CI) was less than one. Treatment of additive intercropping of 50% bean with sunflower had the lowest CI (0.03) and the highest LER (1.66).
Therefore, it seems that additive intercropping of 50% bean with sunflower treatment is suitable treatment for maximum production in society of sunflower and bean.

Saffron (Crocus sativus L.) is a subtropical plant mostly cultivated in South Khorasan and Khorasan Razavi provinces, Iran. Total saffron production is about 200 ton all over the world, and since it is native to Iran, the country has an important role to produce saffron. In recent years, drought showed a significant effect on water resources in Birjand, South Khorasan. Due to lack of full equipped meteorological stations and sufficient lysimetery studies, over irrigation and deficit irrigation are mostly common among saffron farmers. The cause of saffron yield decline is mostly related to irrigation. In addition, farmers need the simple equation/formula to determine the water demand, so, it is necessary to present a single and simple equation. Regarding to this purpose, this study was conducted to achieve mentioned goals: 1) determination of the best evapotranspiration equation, 2) comparison of saffron water need based on 12 most relevant evapotranspiration equations, and 3) determination a single-parameter model to rapidly and accurately estimate saffron water need based on gamma test (due to lack of all FAO-Penman-Monteith parameters in all Birjand’s meteorological stations).
This study was conducted using meteorological data collected from Birjand´s synoptic station during 1984-2014. This station is located at longitude 59˚ 21' E and latitude 32˚ 87' N and elevation 1491m. Twelve evapot ranspiration equations (Blaney-Criddle, Hargreaves, Turc, Priestley-Taylor, Thornthwaite, Jensen-Haise, Makkink, Modified Jensen-Haise, Irmak (Rn), Irmak (Rs), Lowry-Johnson, Pan-Class A) were evaluate to determine the best accurate one. To compare the 12 evapotranspiration equations results with FAO-Penman-Monteith equation (FAO56-PM), four statistical criteria (R2, MBE, RMSE and EF) were used. In order to comprise saffron water demand to actual water used, amount of irrigation water for saffron cultivation in Birjand plain was measured during 2014. In addition, saffron yield was recorded during this growing season in this region. In order to propose a single parameter and accurate model based on easily accessible meteorological parameters, gamma test was also employed.
Results of coefficient of determination (R2) were acceptable (>0.9) for all equations except Turk. The results showed that Blaney-Criddle, Modified Jensen-Haise and Hargreaves had better accuracy compared to other equations so that their root mean square errors (RMSE) were 0.572, 0.721 and 0.945 mm.d-1, respectively. In addition, saffron water requirement determined with FAO56-PM was equal to 2350 m3.ha-1.y-1. Hargreaves equation, with differences about -161.23 m3.ha-1.y-1 compared with FAO56-PM, was determined as a good equation. Measured irrigation water by saffron farmers was about 1184.17 m3.ha-1.y-1. According to the results it found that deficit irrigation was applied by saffron farmers. Saffron grow in arid regions, however, drought stress have a negative effect on its plant development and yield (Khorramdel et al., 2014; Khashei Siuki et al., 2015). Despite the lack of doing no test about the effect of deficit irrigation on saffron yield during 2014 in this region, it seems that deficit irrigation may be a reason of low saffron yield (SYASK, 2010) compared to average saffron yield in this region.
Results of gamma test revealed that temperature is a key parameter to develop a single model. In addition, results showed that the single parameter model based on temperature had better accuracy compared to above-twelve mentioned equation.
Hargreaves equation was only used the temperature (T) and extraterrestrial radiation (Ra) for estimating evapotranspiration. In addition, single parameter equation based on the mean temperature was only used one parameter (T) to estimate the evapotranspiration. Since both of the equations had an acceptable accuracy to use in this region, it is recommended to use them to determine saffron irrigation demand. It is due to lack of meteorological equipment for estimating all parameters in the plain.

Cumin (Cuminum cyminum L.) is an annual plant that commonly cultivated in arid and semiarid regions of Iran. The crop has a wide range of uses including medicinal, cosmetic and food industry. Cumin occupies about 26% of total area devoted to medicinal plants in Iran. However, cumin is seriously affected by the Fusarium wilt and blight diseases. The diseases usually increase under warm and wet conditions.
Control of the diseases incidence is a crucial factor for cumin production. Limited control of the diseases is provided by seed pre-sowing with certain fungicides such as benlate. Soil fumigation with methyle bromide can provide a control measure against the disease but may be limited application value for large scale production systems in the open field. In addition, methyle bromide is considered an ozone-depleting compound and has potential risk on the living environment and human health. Considering the environmental limitations of chemical fungicides, it seems appropriate to search for a supplemental control strategy .It was demonstrated that peak of the diseases incidence is occurred at flowering stage and irrigation cut-off in this time may be reduced the diseases density.
This experiment was conducted in a split-split-plot arrangement in randomized complete block design with three replications in research farm of Shahid Bahonar University of Kerman at 2014. The experimental treatments were irrigation (complete irrigation and cut-off the irrigation in flowering stage) assigned to main plots, foliar application of spermidine (0, 1 and 2 Mm) as subplot and cumin ecotypes (Kerman, Khorasan and Esfahan) that was randomized in sub-subplot. The seedbed preparation was made based on common practices at the location. Plots size under the trial was 4 m×3 m so as to get 50 cm inter row spacing in six rows. The ideal density of the crops was considered as 120 plant.m-2. As soon as the seeds were sown, irrigation continued every 10 days. Foliar application of spermidine was done at three stage (after thinning, before flowering stage and median of flowering stage). No herbicides and chemical fertilizers were applied during the course of the trials and weeding was done manually when necessary.
For extraction of cumin essential oil, from each plot, cumin seed were crushed at 50 g by electric grinder and suspended in 750 mL distilled water. Ground mass was subjected to hydro-distillation using Clevenger's apparatus. After 4 h, the essential oils were collected and dehydrated with Na2SO4 using the method of Guenther. Then essential oil yield and percentage was determined. GC/MS machine (Shimadzu GC/MS model QP5050) was used to specify the percentage of cumin essential oil components.
The results showed that irrigation and ecotype treatments had significant effect on essential oil percentage and yield, but there was not significant difference between foliar application levels in terms of the traits. The irrigation cut-off treatment caused to increase in percentage and decrease in yield of essential oil compared to complete irrigation conditions. The pharmaceutical value of medicinal plants depends on their secondary metabolite components and these materials are increased by stress. Therefore, drought stress caused to higher secondary metabolite including essential oil. The seed yield in comparison with essential oil percentage had more effect on essential oil yield. The traits were significantly higher in Kerman and Khorasan ecotypes than Esfahan. The highest essential oil yield (14.92 kg.ha-1) was gained in 1 Mm spermidine for Khorasan ecotype and the lowest (6.87 kg.ha-1) was observed in 0 Mm spermidine for Esfahan ecotype. p-Cymene, γ-Terpinene, Cuminaldehyde, p-Mentha-1,4-dien-7-ol and ɣ-Terpinene-7-al were contained the main components of essential oil in all the ecotypes. The most important component of essential oil in Kerman and Khorasan ecotypes was Cuminaldehyde and in Esfahan was ɣ-Terpinene-7-al. In essence, Kerman and Khorasan ecotypes had more similarity based on components of essential oil Similar compounds are reported by Iacobellis, (2005), Fanaei et al. (2006) and Jirovest and Buchbouer, (2005).
In essence, irrigation cut-off in flowering stage caused to significant increase in percentage and decrease in yield of cumin essential oil compared to complete irrigation conditions. Kerman and Khorasan ecotypes had higher essential oil percentage and yield than Esfahan. The most important component of essential oil in Kerman and Khorasan ecotypes was Cuminaldehyde and in Esfahan was ɣ-Terpinene-7-al.

Integrated nutrient management involving crop residue/green manures and chemical fertilizer is potential alternative to provide a balanced supply of nutrients, enhance soil quality and thereby sustain higher productivity. The present experiment was undertaken to evaluate the effect of different crop residue management practices and NPK levels on yield components and yield of wheat.
Field experiments were conducted during 2012-2014 at department of agronomy, Chamran University. Experiment was laid out in a randomized block designs in split plot arrangement. With three replications. Crop residues were assigned to main plot consistent CR1: wheat residue; CR2: rape residue; CR3: barley residue; CR4: barley residue vetch; CR5: wheat straw mungbean; CR6: vetch residue; CR7: mungbean residue; CR8: No residue incorporation as main plot and three NPK fertilizer rates: F1: (180N-120P-100K kg.ha-1); F2: (140N-90P-80K kg.ha-1); F3: (90N-60P-40K kg.ha-1) as sub plots. Twelve hills were collected at physiological maturity for measuring yield components from surrounding area of grain yield harvest area. Yield components, viz. number of spike per m2, seed per spike, 1000- grain weight, plant height were measured. Grain and straw yields were recorded from the central 5 m2 grain yield harvest area of each treatment and harvest index was calculated. Data were subjected to analysis by SAS and mean companions were performed using the Duncan multiple range test producer. Also, graphs were drawn in Excel software.
The result of analysis variance showed significant difference between crop residues for evaluated traits. The result indicated that the highest biological and grain yield was obtained when wheat treated with CR5: wheat straw mungbean (green manure) and CR4: barley straw vetch (green manure). Biological and grain yield increased 31 and 26% respectively by CR5 comparing with control. The highest grain and biological yield resulted from the treated plants with F1 there was no difference among F2 and F1 fertilizer rate for grain yield of wheat. Also cereal straw legume (GM) in CR4 and CR5 treatments in F2 performed better than F1 fertilizer in no residue treatment and Wheat grain yield under F2 × CR5 treatments was 25% greater than under F1 × CR8 treatments. The combined use of NPK fertilizer plays an important role in wheat production. Application of NPK in balanced share at proper time has great impact on wheat yield. In order to achieve higher crop production, balanced and integrated nutrient supply and proper management of soil fertility is essential. Application of crop residues/green manures along with suitable does of major nutrients for efficient growth of crop prevent the decline in organic carbon and also bridge up gap between potential and actual yield of wheat. Further, use of crop residue had favorable effect on physic chemical and biological properties of soil due to supply of macro and micro-nutrients to crop properly. Furthermore the decomposition and mineralization of crop residue is a slow process which could match the nutrient requirement of crop. The protein percentage, which is higher in CR5 and CR4 ,shows in whole crop residue treatments, the lowest valuable in F3 and improves with the increase in fertilization researching the highest value with the rate F1. No significant difference was observed between the rate F2 and F3; this would suggest a lower efficiency of the latter, at least for protein accumulation.
Increased wheat yield and component yield due to different crop residue incorporation and NPK rate were reported by Verhulst et al. (2011) and Aulakh et al. (2012).
Application of (140N- 90P- 80K) kg.ha-1 and straw wheat along with mungbean and application straw barley green manure was more effective than (180N- 120P- 100K kg.ha-1) application in no residue incorporation on grain yield and based on this research findings, the use of good quality crop residue, can achieve high yield while saving in NPK fertilizer usage. The reaction yield is less affected by chemical input.

Safflower) Carthamus tinctorius L.) is a tolerant plant to water deficit due to long roots and capability for high water absorption from soil deeper parts. Safflower can growth successfully in regions with low soil fertility and temperature. Behdani and Mosavifar (2011) reported that drought stress affect on yield by reducing yield components and agronomic traits. Biofertilizer during a biological process chanced the nutrients from unusable to usable form for plants in soils (Aseretal, 2008). Mirzakhani et al. (2008) found that inoculation of seed with free-living bacterium azotobacter and a symbiotic fungus productive mycorrhiza addition to increasing oil and seed cause increasing resistance against two factors of unfavorable environmental and to improve quality of product. In order to study the effect of biological and chemical fertilizers on oil, seed yield and some of agronomic traits of Safflower under irrigation of different regimes an experimental design was conducted.
In order to study the effect of biological and chemical fertilizers on oil, seed yield and some of agronomic traits of safflower under irrigation of different regimes an experiment was carried out split plot based on randomized complete block design (RCBD) with three replications in experimental farm of payame-Noor university of Zabol during 2012-2013 growing season. Irrigation regime in three levels include: I1 (control) irrigation in all growth stages, I2 stop irrigation from sowing to flowering (irrigation in growth stages flowering, and seed filling), I3 irrigation in growth stages rosset, stem elongation, heading and stop irrigation in flowering, and seed filling were as main plots and fertilizer resources in five levels included: F1 non application chemical fertilizer (control), F2 pure application chemical fertilizer (NPK) 99, 44 and 123 kg.ha-1 respectively, F3 Nitroxin application (2 L.ha-1) F4 Azotobacter application (2 L.ha-1) and F5 Nitrokara application (100 g.ha-1) were sub plots. Bio-fertilizers mixed with seeds before planting based on manufacturer's recommendations. Fertilizers were applied at ratio of 123 kg.ha-1 potassium based on (K2O), of sulphatedipotash, 44 kg.ha-1 phosphor based on (P2O5) of super-phosphate triple respectively, (based on the results of above soil analysis) along with one-third of 99 kg.ha-1 pure N based on Urea prior to sowing. Other two-third of N was applied at the start stem and heading stages respectively. All other agricultural practices (weeds control and irrigation), were performed when they were required and as recommended for commercial safflower production. A random sample of five plants was selected from each plot in physiological ripening to estimate the different parameters. Data were analyzed by using Mstat-C statistical package (Mstat-C, Version 1.41, Crop and Sciences Department, Michigan State University, USA). Duncan Multiple Range Test was used to do mean comparisons.
Analysis of variance showed that the effect of irrigation and fertilizer resources on yield, yield components, oil yield and RWC were significant. Results showed that seed yield in treatment non stress with mean 1539 than stop irrigation in vegetative phase (rosset, stem elongation, heading), and stop irrigation in reproductive phase (flowering, and seed filling) had increased 45 and 27 percent, respectively. High yield by increasing yield components under water supply reported by Behdani & Mosavifar, (2011). However there was no significant difference from aspect seed yield between biological fertilizers, but Nitrokara bio-fertilizer showed 19 percent increase than non-application - chemical fertilizer (control). Biofertilizer able during a biological process, chanced the nutrients from unusable to usable form for plants in soils. By increasing stress severity, leaf relative water content (RWC) than (control) irrigation in all growth stages decreased, so lowest RWC obversed when irrigation was cut in vegetative phase (rosset, stem elongation, heading). Increasing duration and intensity of stress had an impact on loweringRWC. Reduction in the RWC under drought stress by Behdani & Mosavifar, (2011), has been reported in safflower but with, application bio-fertilizers chances in RWC were increasing. Data analysis showed that interaction effect of bio-fertilizer treatment and drought stress on seed yield was significant.
In general, results of the present study revealed that irrigation in all growth stages, especially in stages sensitive to drought (flowering, and seed filling) and application of biological fertilizers adapted such as: Nitrokara and Nitroxin had positive effects in improving quantitative and qualitative yield of Safflower.

Moisture limitation is considered as one of the important limiting factors in soybean growth. Drought stress affects different aspects of soybean growth through making anatomical, physiological and biochemical changes (Tarumingkeng & Coto, 2003). Under dry tension condition, there will be a disturbance in transmitting nutrients, but some useful soil fungi such as mycorrhiza improve production of crops under stress through forming colonies in the root and boosting water and nutrient absorption (Al-Karaki et al., 2004). Using vermicompost in sustainable agriculture strengthens support and activities of beneficial soil microorganisms (such as mycorrhizal fungi and phosphate solubilizing microorganisms) in order to provide nutrients required by plants like nitrogen, phosphorus and soluble potassium as well as improving the growth and performance of the crops (Arancon et al., 2004).
In order to investigate the effects of vermicompost and mycorrhiza fertilizers on grain yield and some physiological characteristics of soybean under water stress condition an experiment was conducted at Agricultural Research Center of Khorramabad during 2013. The field experiment was carried out based on a randomized complete blocks design arranged in split-plot with four replications. The experiment treatments including irrigation in three levels (after 60, 120 and 180 mm evaporation from pan class A pan), nutrient management in six levels (non-use of vermicompost and mycorhiza fertilizer, inoculated with mycorrhiza fertilizer, consumption of 5 and 10 t.ha-1 vermicompost, consumption of 5 and 10 t.ha-1 vermicompost with mycorrhiza) were respectively as the main plots and sub. In current study, RWC, LAI, SPAD were measured during 59 days after planting at the beginning of podding of the control treatment. The temperature of plant leaves were measured by the thermometer (model TM-958 LUTRON infrared Thermometers). To analyze the growth of grains under different treatments totally 7 samples were performed from flowering to harvest through checking the process of grain weight changes and final grain weight were determined during physiological maturation (when dry grain weight is fixed or changes are not significant). Filling rate and the effective grain filling period were measured using relevant formula. The grain yield measured at the time of maturing after harvesting 3 m² per two middle lines in the plot and through eliminating the fringes of the midfield. All statistical analyzes including variance analysis, comparison of means and interactional slicing using SAS software was done. Mean comparisons using LSD test at the probability of error of 5% was done.
The results of this study concluded that by increasing stress intensity, traits of this research with negative effect on economic performance led to irreparable damage to crop plants. So the lowest grain yield with the rate of 3216.7 kg.ha-1 obtained from 180 mm evaporation. So it is expected to take steps to increase performance by avoiding or minimizing the impact of stress. So that the combined use of these fertilizers had a positive effect on reducing plant leaves heat in low and high water stress condition. Most grain yield obtained by combined treatment of 5 and 10 t.ha-1 vermicompost with mycorrhiza that respectively was 23 and 29 percent more than control treatment. In response to levels of fertilizer, the highest amount of LAI, RWC, Final grain weight and effective grain filling period obtained in vermicompost combined with mycorrhiza treatments.
It seems that the use of vermicompost and mycorrhizal fertilizer combination in areas that are subjected to water stress from improvement of plant physiologic condition can be cause improvement of plant growth conditioning and obtaining higher yielding. Accordingly, for saving irrigation water and cost inputs, farming management and achieving the favorite yield under water deficit conditions, it is recommended to use 5 t.h-1 vermicompost with mycorrhiza for growing L17 soybean.

Given the importance of nitrogen for improving the quantitative and qualitative yield of crops (Rodrigues et al., 2006) and the need for application of chemical fertilizers in intensive agriculture to get the maximum production, nitrogen supply in adequate amounts by ecologically avowed resources is known as one of the main challenges during transition from conventional to organic farming (Rodrigues et al., 2006).
Considering the sustainable nitrogen management, reconstruction and rehabilitation of agroecosystems depends on reduction the nitrogen losses due to leaching, soil erosion and volatilization (Kizilkaya, 2008). For this purpose, the use of eco-friendly bio based fertilizers that are derived from natural origin, known as effective and enforceable approaches. In this regards, the proper use of manure and free-living aerobic bacteria of soils, such as Azotobacter and Azospirillum as well as mycorrhizal inoculation which can be used as a biological fertilizers, can particularly be considered (Kizilkaya, 2008).
With regard to all mentioned above, the current study was aimed to evaluate the effects of biological, organic and inorganic resources of nitrogen on yield and yield components of black seed (Nigella sativa L.).
The field experiment was conducted at Faculty of Agriculture, Ferdowsi University of Mashhad, Iran, in years of 2009-2010. Experimental site was located in a semi-arid region, Khorasan Province, Northeast of Iran. The soil texture was silty loam, pH 8.36, electrical conductivity 3.72 dS.m-1, total N 0.095% and 0.195% organic carbon. The available P and K contents were 5.76 and 0.378 ppm, respectively.
Experimental design was arranged by using a completely randomized block design with three replications. Experimental treatments included chemical fertilizer (urea), urea nitroxin, urea mycorrhizae, urea nitroxin mycorrhizae, urea biosulfur, manure, manure nitroxin, manure mycorrhizae, manure nitroxin mycorrhizae, manure biosulfur and control.
Plots were designed with 4 m long and 2 m width (8 m2), 0.5 m apart each other. Seed sowing was done at 18th March on both sides of the furrows. Final plant density was determined equal to 200 plants m-2. At maturity stage, number of branch per plant, number of follicle per plant, seed weight per follicle and 1000- seed weight were determined based on randomly selection of eight plant. Moreover, grain and biological yields as well as harvest index of black seed were measured by considering the side effects.
For statistical analysis, Duncan multiple range test (p≤0.05) was used to separate the experimental means using SAS 9.1 software.
According to the results, effects of urea and cow manure treatments on grain and biological yields of black seed were significant. However, cow manure, in comparison with urea fertilizer, had more significant effects in increasing mentioned traits of black seed. For instance, cow manure treatment increased grain yield by 25%, compared with urea treatment.
Generally, advantages of manure in comparison with chemical fertilizer can be related to the slow and more balanced release of nutrient contents as well as improving the physical and chemical soil characteristics over growing season. On the other hand, the results showed that biological fertilizers had no effects in increasing grain and biological yields of black seed, except biosulfur treatment.
From the results, there was a positive correlation between 1000- seed weight with grain yield. Moreover, similar correlations were found between number of branch per plant and grain yield, number of follicle per plant and grain yield as well as seed weight per follicle and grain yield. Nonetheless, relationship between harvest index and grain yield was determined as a negative correlation. These results are in agreement with those of Moradi et al. (2010) who found a significant decrease in harvest index of Fennel (Foeniculum Vulgare L.) affected by organic and biological fertilizers. It seem that under no application of organic or chemical fertilizers, black seed mother plants prefer to allocate more assimilation materials to the reproductive growth; therefore, plant harvest index can be increased possibly.
In sustainable agriculture, applying eco-friendly input can be considered as a principle approach for increasing plant production. Therefore, in regions with alkalic soils, applying the organic fertilizer (such as cow manure) and biological biofertilizer (e.g. biosulfure) can be suitable in reducing the problems caused by consecutive and excessive using of chemical fertilizers.

Due to its multifunctional nature agriculture play important roles in ecological processes such as carbon sequestration, flood control, groundwater recharge, nutrient cycling, and purifying water, soil and air in addition to providing food, feed and fiber. These cover almost all ecological services provided by natural ecosystems, including provisioning services, regulating services, supporting services and cultural services (MEA, 2005). Provisioning services are the products obtained from ecosystems, including food, fiber and fuel. Regulating services are the benefits arising from the regulation of ecosystem processes, such as climate regulation, water purification, pollination and the control of pests and diseases. Cultural services are the non-material benefits people obtain from ecosystems, as spiritual enrichment, recreation and aesthetic experiences. Supporting services are those services necessary for the production of all other ecosystem services, such as soil formation and nutrient cycling (Norris et al., 2010). However, most of these services are not recognized and their values are hidden to the society. On the other hand, unlike natural ecosystems that only produce positive ecological services, agro-ecosystems also contribute to some negative externalities e.g. emission of greenhouse gases, leaching of chemicals into soil and water resources and reduction of biodiversity that should be taken into account (Norris et al., 2010). Economic valuation of these services makes them attractive for the society and policymakers to pay more attention towards conservation of ecosystem services. In Iran, studies on ecosystem services are scared and in global scale researches are mainly focused on natural ecosystems. In this study the economic value of ecological services as well as negative environmental externalities of wheat fields were estimated in the Khorasan Razavi province.
Information was extracted from questionnaires collected from 40 fields varying in area, management and inputs level. Using these data economic value of feed and food, carbon sequestration, oxygen production, biodiversity, water retention and tourism together with greenhouse gas emission and nitrogen and phosphorous leakage as environmental externalities was quantified. Calculations were based on standard methods described by Millennium Ecosystem Assessment. Economic values were estimated as international dollar as proposed by De Groot et al. (2012) and reported as equivalent national price.
The mean value of the total agroecosystem services of wheat fields excluding externalities, were estimated as 66.85×106 Rls.ha-1.y-1. The value of non-marketable services was 3.46 times more than food and feed and on average atmospheric services (oxygen production and carbon sequestration) contributed up to 62% of total value while biodiversity and provisional services included 9.3 and 21% of total, respectively and the other services below 5%. Net value of services was increased with increasing field size. However, doubling field size resulted in 50% increase in net value because larger fields were more intensified leading to higher negative impacts. Economic value of services was significantly dependent on wheat total dry matter and yield. Nonlinear relation was found between wheat yield and total value of services where a break point was found at yields above 4 t.ha-1. However, negative externalities were increased linearly with increasing both total dry matter and grain yield.
Results of this study indicated that despite to intensive management wheat production systems of Khorasan province are able to provide several regulating and supporting services and their economic value is 3-4 folds higher than provisional services harvested as grain and feed. However, negative externalities will be increased in more intensified fields with higher yield. Feeding a growing human population is obviously critically important and can only be done by recognizing and embracing the concept that food production systems are embedded within ecosystems. They depend on ecosystem services and have ecosystem impacts. Promotion of multifunctional characteristics of agroecosystems to maintain high yield together with ecological services, should be considered as an alternative for conventional management practices.

Corn (Zea mays L.) is the third most important cereal crop in the world after wheat and rice (Lashkari et al., 2011). Corn production has been extended in to the whole world during the course of the last century due to its compatibility. It has more diversity compare to other cereal. Many corn types are cultivated, including field corn, ornamental corn, popcorn, sweet corn and several different supersweet corns. Sweet corn, considered a vegetable, is a special type of corn with particular characteristics, such as sweet taste, thin pericarp and endosperm with delicate texture, and high nutritional value. It is destined exclusively for human consumption, in fresh form or in processed foods, whereas the straw can be used for silage after harvest (Santos et al., 2014). Sweet corn seeds germinate slowly and exhibit poor seedling vigour. Poor germination in sweet corn has been attributed to low seed vigour and susceptibility to seed and soilborne diseases (Ratin et al., 2006). Seed priming is the one of efficient method to improve germination and emergence. In addition, transplanting provides optimal environmental conditions for seed germination and avoids planting seeds in disease-contaminated soil (Khalid et al., 2012).
To investigate the effect of seed priming and transplanting on morphological characteristics, yield and yield components of supersweet corn a series of greenhouse and field experiments were conducted in a factorial based design on a randomized complete block in 2013. This experiment was conducted in the greenhouse to determine the best seed priming treatments. The treatments were hydro priming, Poly ethylene glycol (6000) -0.4 and -0.8 MPa, Sodium Sulphate 0.1 and 0.5%, Zinc Sulphate 1 and 0.5%, Copper Sulphate 0.1 and 0.5% and Control for 36 hours. After that the seeds washed by distillated water and dried back in laboratory conditions. Then treated seeds were sown in trays that contained by cocopeatand vermicompost. The emerged seeds were counted daily for fourteen days. Based on mean emergence time (MET) and percentages of emergence, the best priming treatments were selected to prime the seeds for transplant production and direct sowing in the field experiment. The factors for field experiment included four treatments of seed priming (hydropriming, polyethylene glycol (PEG) -0.4 MPa, sodium sulfate 0.1% and control) and planting methods in four levels (transplanting the seedlings grown in two different cell sizes (25 ml and 100 ml) and two direct seeding dates (the first one was at the time of planting seeds in the trays (5th June) and the second was at the time of transplanting to the field (26th June)). The determined parameters were established plants, plant height, number of leave, number of leave above ear, ear length, number of rows per ear, number of kernel per row, 1000 seeds weight and grain yield.
The results of greenhouse experiment showed that the highest and the lowest amount of mean emergence time related to control and Sodium Sulphate 0.1% respectively. The highest percent of emerged plant (94%) was observed in the hydropriming treatment while there was no significant difference between hydropriming, Sodium Sulphate 0.1 % and Polyethylen Glycol -0.4 MPa. Therefore, hydropriming, Sodium Sulphate 0.1 % and Polyethylen Glycol -0.4 MPa alongside control were used to prime the seeds sowing in order to produce transplants for the field experiment for further investigation. The results of the field experiment showed that seed priming had no effect on the studied traits in the field. Planting methods had significant effect on crop establishment, plant height, number of leave, number of leave above ear, ear length, number of rows per ear, number of kernel per row and the grain yield. The highest and lowest grain yield were recorded for transplanting in 25 CC cell sizes (10.11 t.ha-1) and direct seeding in 26th June (6.5 t.ha-1) respectively. The result showed there was a high correlation (r =0.64**) between number of established plants and grain yield.
Priming was not useful in field, but farmers could use seed priming to produce seedlings. It seems that the most important benefit of transplanting is obtaining high value of plant establishment in order to achieve optimum plant density.