AGROECOLOGY (بوم شناسی کشاورزی)
Year:2021 | Volume:13 | Issue:1|Papers Count:11

Introduction In recent decades, agricultural production has largely relied on the use of chemical inputs, which has led to major environmental problems. Destruction of water and soil resources, deterioration of agricultural biodiversity, air and water pollution by chemical fertilizers and pesticides are only part of the environmental problems caused by common agricultural use of chemical inputs. One of the solutions to this problem is to apply sustainable farming principles in agricultural ecosystems. Soil management is one of the main factors in achieving sustainable agriculture. Therefore, the gradual replacement of chemical fertilizers with organic and biofertilizers will help to meet the nutritional needs of plants, improve the physical, chemical and biological conditions of the soil and prevent the adverse environmental effects of chemical applications. Organic matter has been recognized as one of the nutrients of plant nutrition and fertility due to its constitutive effects on soil physiological and biological properties. Organic fertilizers are the most important source of organic matter in the rhizosphere of plants. Black seed is an annual, dicotyledonous, herbaceous, medicinal plant belonging to the Ranunculaceae family. Environmental conditions and soil fertility are one of the factors affecting grain yield, quantity and quality of essential oil and oil produced in black seed. Since there is not much research on the effect of humic acid and fulvic acid on black seed, therefore, attention to the management of nutritional needs of black seed with emphasis on the use of biological and organic fertilizers in the successful cultivation of this plant is inevitable. Materials and Methods In order to evaluate the effects of organic, biological and chemical fertilizers on yield, yield components and oil yield of black seed, a field experiment was conducted at Research Station, Faculty of Agriculture, Ferdowsi University of Mashhad, Iran, during the growing season of 2011-2012. The experimental layout was factorial based on randomized complete block design with three replications. Experimental treatments included all combinations of organic and biological fertilizers factor in four levels (biosulfure + 100 kg. ha-1 sulphor, humic acid (7 kg. ha-1), fulvic acid (7 kg. ha-1) and control) and chemical and animal manure factor in three levels (chemical fertilizer (NPK (80: 40: 30 kg. ha-1, respectively), animal manure (20 t. ha-1) and control). In order to determine the oil content, 5 grams of grain were randomly selected from the grains harvested from each plot and then oil content was determined by Soxhlet. Analysis of variance (ANOVA) and regression analysis of the data from the experiment and drawing of shapes were performed using SAS and MSTAT software's. Comparisons of means were performed at 1 and 5% probability level using Duncan multiple range test. Results and Discussion The Results showed that studied factors and their interactions had significant effect on number of seed per plant, seed weight/plant, seed yield and oil yield. The highest plant height, number of branch per plant, number of follicles per plant, number of seeds per follicles, number of seeds per plant, seed weight per plant, seed yield and oil yield (59 cm, 5. 8, 7. 8, 72, 594, 1. 075g, 2. 2 (t. ha-1), 517 (kg. ha-1), respectively) were observed in chemical fertilizer + biosulfur biofertilizer treatment and the lowest mentioned traits (49 cm, 3. 01, 3. 92, 39. 8, 194, 0. 445, 0. 935 (t. ha-1), 221 (kg. ha-1) respectively) were observed in control treatment. The highest and lowest harvest indexes were observed in animal fertilizer + humic acid (49%) and control (25. 6%) treatments, respectively. The highest and lowest oil percentages were observed in animal fertilizer + humic acid (49%) and control (25. 6%) treatments, respectively. The results indicated that the use of humic and fulvic acids, and biosulfur biofertilizer alone or in combination with chemical fertilizers and animal manure improve the quantity and quality of Nigella sativa characteristics. Conclusion The results of this study revealed that considering the positive response of the black seed to application of organic and biological fertilizers, applying these fertilizers while reducing the use of chemical fertilizers as well as having no adverse environmental effects is an appropriate method for sustainable production and environmental protection.

Introduction Nowadays, with increasing tendency to monoculture of medicinal and horticultural plants, the range of genetic diversity in agricultural ecosystems has decreased. Conventional agricultural activities with simplification of ecosystems makes ecosystems more unstable and more sensitive to environmental hazards. Therefore, the promotion of biodiversity in these systems is effective for their recovery and sustainability. The purpose of designing sustainable agricultural ecosystems is to integrate ecosystem components in such a way that maintains and strengthens the biodiversity, productivity and self-regulatory capacity of the agricultural ecosystem. Functional diversity is achieved by using different functional species with different roles in agroecosystems. The role of weeds in increasing diversity in agroecosystems is very important because they are closely associated with many of the crops and genetic exchange between them. The presence of weeds in the crop ecosystem reduces genetic vulnerability through strategy of environmental diversification as well as the occurrence of resistance mechanisms. Materials and Methods In order to investigate the effect of some medicinal plants on weed density and diversity, an experiment was conducted based on a complete randomized block design with three replications at the agricultural research station, Ferdowsi University of Mashhad, Iran, during 2012 and 2013. Treatments included 13 medicinal species (Origanum vulgar, Hyssopus officinalis, Tanacetum parthenium, Echinacea purpurea, Ruta graveolens, Althea officinalis, Hypericum perforatum, Trigonella foenum-graecum, Oenothera erythrosepala, Malva sylvestris, Securigera securidaca, Achillea millefolium and Digitalis purpurea). After tillage, land preparation and leveling, each plant was cultivated in strips of 10*3 meters. After complete establishment of the plants in order to achieve the desired density, thinning operations were performed on each strip. The distance between the test strips was 0. 5 m. Seeds of all studied plants were sown in April 2012. In both cropping years to study the diversity of weeds, a part of each plot with dimensions of 0. 5 m was separated and remained without weeding and in all plots of medicinal plants, density and dry weight of weeds was determined at two stages of vegetative and reproductive growth of medicinal plants. Also, physiological and morphological characteristics such as height, leaf area and dry weight of plants in each plot were measured. In order to calculate the diversity of weeds, the type of weed species and their density were determined in quadrates with dimensions of 40*40 cm. Then the weeds in each plot were harvested separately and transferred to the laboratory and were placed at 70 ° C for 48 hours to determine the dry weight. Shannon, Margalf and Simpson diversity indices were used to quantify weed diversity. Results and Discussion The results indicated that the effect of medicinal species on total weed density and weight was significant. The highest and the lowest dry weed weight was obtained in Digitalis purpurea (39. 4 g. m-2) and Tanacetum parthenium (3. 2 g. m-2), respectively. The highest total weed density was observed in Malva sylvestris, Securigera securidaca, Digitalis purpurea and Hyssopus officinalis. Malva sylvestris had the highest weed richness (four species) that it was not significantly different with Securigera securidaca and Achillea millefolium. During different sampling years and stages, the highest Shannon index was obtained in Achillea millefolium (0. 48) that it was not different with Malva sylvestris, Securigera securidaca, Hyssopus officinalis, Hypericum perforatum, Digitalis purpurea and Echinacea purpurea, significantly. Also, the highest margalof index was obtained in Malva sylvestris, Achillea millefolium and Hyssopus officinalis (4. 05, 4. 03 and 3. 33, respectively). Studied medicinal species for weed diversity divided to 5 groups in 75% similarity level. Despite the importance of biodiversity for the stability of natural ecosystems and agroecosystems, increasing species and functional diversity, simultaneously, is necessary to improve agroecosystem’ s function. Keep the limited weed population in field increase functional diversity of agricultural landscapes but, this profit must reach equilibrium with the risk of decreasing crop production due to competition with weeds.

Introduction Natural and semi-natural features including those as patches and marginal elements, construct a network of habitats referred to as green vein elements. In the green veining, the linear elements connect the different parts of the network, while the patches have a role as nodes within the network. These networks potentially place a vast range of biodiversity and play an important role as a refuge for sensitive organisms as well as some habitat specialist species. With regards to crop production and pest management in agricultural fields, pollinators and biological control agents, like predators, are among the most beneficial organisms mostly found in green vein elements. As the biodiversity in agroecosystems is considerably declining, this study was conducted to address the important role of natural and semi-natural elements of the landscape in biodiversity conservation. Materials and Methods The study area was an agricultural landscape located in Gilane-Gharb County, Kermanshah Province, Iran with a Mediterranean climate. The level of agricultural intensification (AI) was surveyed through interviewing the farmers and considering the indicators such as chemical and organic fertilizers (Kg N/ha/year), pesticide input (utilization frequency of e. g. herbicides, insecticides and fungicides) and the number of tillage operations and mechanical weed control. by providing the geographic map of the area and frequent field observation, seven different types of patches and marginal habitats were identified, including: 1) arable and horticultural fields (Fi); linear elements adjacent to the fields including: 2) within field edges (W. F. E) and 3) non-crop field edges (N. F. E); 4) roads; ditches including 5) permanent ditches (P. D), 6) non-permanent ditches (N. P. D), and 7) woody greenvein (W. Gr) element. 87 sample plots (2 m × 2 m) were recorded in all the elements. Vegetation data from fields were recorded using 18 sample plots; woody green vein 19 sample plots; and other marginal habitats including within field edges, non-crop field edges, permanent ditches, non-permanent ditches and roads, were sampled by 50 plots. Sampling was done based on systematic-randomized method. Two emergent groups of plant species were introduced regarding their response to land use intensification: Agrotolerant and Nature-value species. The calculated biodiversity indices were: Jackknife species richness, Shannon-wiener, Simpson and Brillion diversity indices, Camargo and Smith-Wilson Evenness, and finally Sorenson Similarity index using Ecological Methodology software. Results and Discussion The calculated agricultural intensification index (AI) was 49. 56; this score was at the range of high intensified agricultural utilization (High AI). Mean observed value of nitrogen input was 211. 36 kg/ha, the weighted frequency of tillage operations and pesticide application per hectare was the same as 2. 36. Apart from crop species, a total of 87 vascular plants were recorded in the agricultural landscape. The highest species richness was for agricultural fields (43 species), which followed by non-crop field edges (37), woody greenveins (32), within field edges (30), permanent ditches (26), non-permanent ditches (23) and roads (22). Sorghum halepense (L. ) Pers. (46. 56% of the total frequency of individuals existing in the field sample plots) was the most frequent species in the landscape. 21 species were recorded as agrotolerant species. Jackknife species richness was 48. 7 in the fields as the most, and 23. 8 in the road verges as the minimum. Woody Green veins (W. Gr) had the most number of unique species. The most Shannon-wiener and Brillion diversity indices were recorded for agrotolerant and nature-value species in within field edges (Shannon-wiener: 2. 03 and Brillion: 1. 85) and fields (2. 52 and 3. 08) respectively. Sorenson similarity index revealed that the elements inhabiting high number of agrotolerant species had a similar spatial condition especially regarding being adjacent to the agricultural fields. Studies reported the outstanding benefits of greenvein elements in promoting plant biodiversity and as a result enhancing diversity of organisms which inhabit in such elements. Conclusion The study indicated the effect of agricultural intensification and types of land use throughout the landscape on biodiversity. Elements with high connectivity to natural or seminatural habitats had the most positive effect on biodiversity of plant spesies. To gain the targets of sustainability in agroecosystems, providing as much as possible natural and semi-natural habitats and corridors are suggested.

Introduction With respect to this issue that Iran is located in semi-arid conditions and limited by water resources, so water conservation in agricultural systems plays main role to increase production and determination of water optimum amount is first step to gain this purpose. Nitrogen is one of the main effective factors on quantity and quality of crops. According to the studies, only 40-60% of nitrogen fertilizers is used by crops and this value decreases with increasing of fertilizer application. There is complicated interaction between amount of irrigation water and nitrogen fertilizer, thus it is necessary to consider optimum level of them simultaneously. To obtain acceptable economical yield and reducing environmental pollutions, used inputs in farms should be applied as optimum with respect to expected target. One of the important methods to gain optimum level of inputs is response-surface method. There is no study to investigate usage of this method for inputs optimization in sugar beet. Therefore, the purpose of the study was optimizing of nitrogen fertilizer and irrigation in sugar beet via the response-surface method by using a central composite design. Material and Methods We used available data and information from studies which had been accomplished about nitrogen fertilizer and irrigation in Hamedan, Iran to determine optimum levels of these treatments. So needed treatments were designed based on high and low levels of nitrogen fertilizer (0 and 240 Kg. ha-1) and irrigation (8000 and 14000 m3. ha-1) by Minitab software ver. 16 as central composite design (CCD). CCD is one of the response-surface methods and the number of treatments in this design is calculated by equation of 2k + 2k + r, where k is the studied factors and r is number of replication for central point. Number of replication for central point under two factors has been reported as 5, thus for central composite design with two factors, 13 treatments is needed. To fit data, regression equation was used and evaluated based on regression variance analysis. In general, the full quadratic polynomial equation was tested to determine the significance of the model and the components of the model. RMSE, ME, R2 indexes and 1: 1 line were used to judge the difference between simulated and observed data. Results and Discussion ANOVA results showed that regression model was significant to estimate all dependent variables based on F test. Correlation coefficient of dependent variables including root yield, sugar and sugar white, water use efficiency and nitrogen use efficiency determined as higher than 96%. It implies that the high proportion of the variability for these traits was explained by the fitted regression model. According to the lower values of RMSE than 10 and higher values of ME than 0. 89, it could be concluded that the model had acceptable and suitable results to estimate studied traits in sugar beet. The results of t-test to compare fitted regression with line 1: 1 illustrated that slope and intercept values in fitted and 1: 1 line had no significant difference. The results showed that root, sugar and white sugar yield were increased by increasing nitrogen fertilizer under all levels of irrigation. Response-surface curve of α-amino nitrogen as affected by irrigation and nitrogen fertilizer indicated that α-amino was elevated by increasing nitrogen fertilizer application. As data, water use efficiency decreased by water consumption. In the other hand, nitrogen use efficiency was decreased by applying nitrogen fertilizer under all levels of irrigation. Optimum range of treatments were obtained as 9500-12000 m3. ha-1 for irrigation and 110-130 Kg. ha-1 for nitrogen fertilizer treatment based on overlaid plot method. The results of treatments optimization by using analytical solution method illustrated that applying 133 Kg. ha-1 and 10667 m3. ha-1 were suggested as optimum amounts of treatments. Based on these optimum levels of treatments, root yield, sugar and white sugar yield, α-amino, water use efficiency and nitrogen use efficiency were estimated as 80. 1 ton. ha-1, 14. 94 ton. ha-1, 12. 49 ton. ha-1, 2. 56 meq. 100 g-1, 1. 39 Kg sugar. m-3 and 74. 24 Kg sugar. Kg-1, respectively. Conclusion As result, to optimize treatments including nitrogen fertilizer and irrigation, response-surface method had acceptable adequate to predict variables in sugar beet based on statistical indexes. Optimum value of nitrogen fertilizer and irrigation were predicted as 133 Kg. ha-1 and 10667 m3. ha-1, respectively by using analytical solution. Therefore, the results indicate that the application of optimum values can reduce environmental hazards and produced acceptable sugar yield.

Introduction Catnip (Nepeta cataria L. ) is one of the most important medicinal plants belonged to the Lamiaceae family that referred to considerable pharmacological, antimicrobial, antibacterial and pesticides activities of its essential oil in most of the literatures. The harmful effects of chemical fertilizers on the environment and human health and lack of soil organic matter in arid and semi-arid regions have resulted in an increase in the use of chemical fertilizers in these areas. Excessive use of these fertilizers has led to serious environmental pollutions during the last decades. With respect to the hazards of chemical fertilizers and the importance of medicinal plants, researchers have recently considered the application of biofertilizers and organic materials. According to literatures, the application of biofertilizers and organic fertilizers can be recommended as a proper alternation for the improvement of the quantity and quality of essential oil in Catnip. Material and Methods This research was conducted as factorial layout based on a randomized complete block design (RCBD) with three replications at the research farm of the faculty of agriculture, Shahid Chamran University of Ahvaz, Iran. The first factor was included fertilizer treatments in five levels (Control (C), Azetobarvar-1 (Az), Phosphatbarvar-2 (Ph), Combination of Az and Ph (M), chemical fertilizer (Ch) included 150 kg. ha-1 granular urea (46% N) and 100 Kg. ha-1 triple superphosphate (46% p < sub>2O5)) and the second factor was comprised humic acid in two levels (0 and 20 Kg. ha-1). The studied traits in this research included soil microbial respiration and biomass carbon and soil organic matter contents, leaf nitrogen and phosphorus amounts, number and size of secretory trichomes, essential oil content, yield and composition. Leaf nitrogen and phosphorus concentrations were measured at the beginning of reproductive stage by Kjeldahl method and colorimetric method using a UV-2100-Unico spectrophotometer, respectively. Moreover, the soil microbial respiration and soil biomass carbon were determined by alkali absorption and the fumigated extraction, respectively, and soil organic matter was estimated by the modified Walkly and Blackʼ s methods. Furthermore, the number and size of secretory trichomes was registered using Binocular microscope and essential oil was extracted by Clevenger-type apparatus and analyzed using GC and GC-MS at full bloom stage. Results and Discussion According to the results, the sole application of fertilizer treatment was positively affected on soil microbial respiration and biomass carbon, leaf nitrogen and phosphorus contents. The number and size of secretory trichomes, essential oil content and yield and essential oil composition were significantly influenced when fertilizer treatments and humic acid were applied simultaneously. The highest amount of soil microbial respiration as well as biomass carbon was detected in M and the lowest was observed in control. The application of Ch and humic acid was significantly improved the soil organic matter. However, no significant difference was found between these treatments and biofertilizers treatments. The lowest amount of soil organic matter was detected in control. The maximum content of leaf nitrogen element was observed in plant treated by Ch and minimum was registered in control. The highest level of leaf phosphorus element, the size of secretory trichomes and essential oil content were obtained when Ph was applied while there was no significant difference between this biofertilizer and Ch and M. The maximum number of secretory trichomes and essential oil yield was detected in plant treated with M. The most amounts of isomers 1 and 2 of nepetalactone and caryophyllene oxide was observed in Az, Ch and control, respectively, and least was in control, Ph and Ch, respectively. The highest level of trans-caryophyllene and (E, E)– Farnesene was obtained in the oil of plant treated with M+ and Ch+ and lowest detected in Az+ and Ch-. Conclusion According to the results, to improve the quantity and quality of Catnip essential oil, the application of biological fertilizers instead of chemical fertilizers is recommended and further research is also required to investigate both the effects of applying humic acid alone and in combination with biofertilizers on some traits.

Introduction Medicinal plants are of the most valuable reserves of natural resources in Iran, and if there is correct recognition of them, these plants can play an important role in the health of the community, employment, and non-oil exports. Fennel (Foeniculum vulgare L. ) is a perennial herb that is one of the most important and is widely used as medicinal plants that is mainly cultivated for the purpose of using essential oils in various industries of pharmaceutical, food, cosmetic and sanitary. Therefore, this research was carried out with the aim of investigating the effects of different concentrations of salicylic acid on the qualitative and quantitative characteristics of fennel under drought stress conditions at phonological stages. Materials and Methods The experiment was conducted as a split-plot based on a randomized complete block design with three replications. The main factor included five levels of irrigation regimes: full irrigation, irrigation at stemming stage, irrigation at a budding stage, irrigation at flowering stage, and irrigation at seed filling stage. The subfactor included four different concentrations of salicylic acid: zero, 3, 6, and 8 mM. In the treatment of irrigation regimes, irrigation proceeded until the end of the growth period after irrigation was discontinued at the growth stage. At the end of the growing season, in order to evaluate the yield components, ten plants per plot were selected randomly, and the yield components were measured. In the southern half of each plot, seed yield was measured after collecting plants and seed separation. The essence of the seeds was extracted by the water distillation method, and the essential oil content was calculated. Results and Discussion The results showed that two treatments for non-application of salicylic acid in irrigation in the grain filling stage and application of six mM of salicylic acid at irrigation at flowering stage obtained the highest number of sub-branches per plant with 21. 3 and 20. 3 sub-branches in the plant, respectively. Treatment of application of 8 mM salicylic acid in irrigation at seed filling stage revealed the largest number of umbrellas per plant and weight of 1000 seeds. The largest number of umbellet per umbrellas belonged to six and eight mM salicylic acid applications in the treatment of irrigation at the seed filling stage. The lowest amount of seeds in the umbellet was observed at different levels of salicylic acid in irrigation at the flowering stage. Treatments of application of 8 mM salicylic acid in irrigation at budding stage and application of zero and three mM salicylic acid incomplete irrigation conditions obtained the highest seed yield by producing more than 790 kg per hectare. Application of zero and three mM salicylic acid at irrigation in seed filling stage showed the highest amount of essential oil by 3. 83 and 3. 73% essential oils, respectively, and after those, two treatments of application of 8 mM salicylic acid at irrigation in the flowering stage and at the time of seed filling were placed at the next rank. Conclusion In general, it seems that the occurrence of drought stress at the flowering stage compared to stress in other stages of development, had the greatest effect on reducing the yield components and grain yield of fennel. Also, the application of salicylic acid in conditions of irrigation removal in the budding stage improved seed yield, as well as at stemming and flowering stage, increased the amount of essential oil of fennel seed. However, its effectiveness did not follow a particular process. In addition, the highest amounts of essential oil were observed at the time of drought stress in the grain filling stage. The results showed that application of zero and three milliliters of salicylic acid produced the highest amount of essential oil at irrigation interruptions in the grain filling stage.

Introduction Today, rapid population growth and economic development have increased demand for food, and climate change has affected food security worldwide. Climate change processes, including increasing the atmospheric carbon dioxide concentration, rising temperature, and fluctuation of precipitation, could directly affect agricultural products. Climate change also causes drought, which indirectly influences agricultural systems as water is the most important for grain yield and its quality. Arid and semi-arid regions are limited in terms of water resources and they are the most fragile regions faced with drought caused by climate change. Khuzestan province is one of the hot and arid regions in Iran which its agricultural crops (especially maize) are very sensitive to climate change. Irrigation schedules and various cultivars can be considered as the adaptation strategies according to the climate change conditions. In agricultural ecosystems, water consumption should be reduced, and grain yield should be increased as much as possible. Optimizing water consumption by improving water use efficiency (WUE) is essential for achieving agricultural sustainability in arid and semi-arid regions. Accordingly, modelling approach has been considered as a time-saving and low-cost way to study the effects of climate change and different treatments. The current study was conducted to investigate the effects of different irrigation management practices on maize grain yield and WUE under climate change conditions in order to optimize water consumption and WUE by using modeling approach. Material and Methods The current study was carried out in several locations of Khuzestan province, including Dezful, Izeh, Bostan, and Ahwaz. The long-term climatic data of the studied locations were collected from the Iran Meteorological Organization. These data included minimum and maximum temperatures (° C), rainfall (mm), and solar radiation (MJ m-2) from 1980 to 2010. Angstrom equation was used for calculating the radiation based on sunshine hours. The climatic data were modified using WeatherMan software embedded in the DSSAT package. The future climate of Khuzestan province (2040-2070) was predicted by the MIROC5 general circulation model under the RCP4. 5 climate scenario and using AgMIP methodology. According to the previous studies, the MIROC5 climatic model showed the highest accuracy in predicting the future climatic data of Khuzestan province. Two adaptation strategies, including cultivar and irrigation regime, were considered to mitigate the negative effects of climate change. The cultivars consisted of SC704 (late-maturity) and SC206 (mid-maturity), which had the highest area under cultivation in Khuzestan province. Irrigation regimes included three levels: 12-time irrigation (as farmers’ common practice), 10– time irrigation, and 14-time irrigation per growing season. Results and Discussion The results of the current study indicated that climate change had negative effects on maize grain yield as well as positive effects on average temperature during the growing season, evapotranspiration, and corn water use efficiency across the whole province. The results showed that the average grain yield and corn WUE in Khuzestan province in 2050 under the RCP4. 5 scenario was-2% and-5. 7%, respectively, compared to the baseline. In addition, mean temperature during the growing season and evaporation and transpiration increased by +12. 6% and + 0. 9% compared to the baseline. The results also showed that with the application of an optimal amount of irrigation regime (10-time irrigation), an increase in WUE and decrease in evapotranspiration were observed, which resulted in acceptable grain yield. Results also portrayed that applying the optimal irrigation level (10-time) along with a late maturity cultivar (SC704) showed the best performance in terms of grain yield (9433. 9 kgha-1) and WUE (19. 57 kgha-1 mm-1) in the province Khuzestan. Conclusion The results illustrated that by 2050, the average grain yield and WUE were reduced compared to the baseline period. However, the mean temperature and evapotranspiration over the growing season were increased. Totally, the results of the current study revealed that an optimal irrigation level 10 and suitable cultivar SC704 could mitigate the negative impacts of climate change on maize in the agroecosystems of Khuzestan province.

Introduction Weeds are one of the major reducing factors in tomato production. Cover crops have several features that can inhibit germination and decline emergence and establishment of weeds. The aim of this research was to investigate weed control by using winter cover crop species in production of tomato crops. Materials and Methods The experiment was conducted as split plot based on a randomized complete block design at Sabouri Field, Khorasan Razavi Agricultural and Natural Resources Research and Education Center during 2017-2018. Four winter cover crops (WCC) [such as chickling pea (Lathyrus sativus), hairy vetch (Vicia villosa), fenugreek (Trigonella foenum-graecum) and rye (Secale cereale)], irrigation (tilled soil without WCC) and control (tilled soil without irrigation) were considered as main factor and sub plots were two tomato cultivars (8320 and 6515 from FALAT Co. ). WCC were converted into mulches in spring. Studied criteria were relative density, density and dry weight of weeds per unit area and number (in three stages such as 30 days after planting time, 50 days after planting time and before planting time) and fruit yield and Brix index in three ripening stages. Results and discussion The results showed that species of weeds controlled varies widely between WCCs. The minimum density and dry weight of weeds were belonged to hairy vetch and rye and the maximum was for control. Hairy vetch and rye are allelopathic with better efficacy against annual dicots than grasses. The simple and interaction effect of WCC and cultivar were significant on fruit number, fruit yield and Brix index. The highest and the lowest yield for the first, second and third ripening stages were observed in hairy vetch and control, respectively. Total yield for 6515 cultivar was 15 percent higher than 8320 cultivar. The highest and the lowest fruit numbers for the first, second and third ripening stages were related to hairy vetch (with 75. 31, 37. 78 and 22. 3 fruits. m-2) and control (with 54. 33, 22. 78 and 8. 85 fruits. m-2), respectively. Brix index for 8320 cultivar was higher than 6515 cultivar. Conclusion In general, annual, biennial or perennial weeds are suppressed by WCCs. This research indicate that WCCs could be used successfully in integrated weed management to decline weed infestation in tomato production.

Introduction[1] Nowadays, agriculture plays a major role in environmental pollution, and knowledge regarding reducing input utilization in such systems can help us to decrease the limited input resource consumption and the consequent greenhouse gas (GHGs) emissions and environmental impacts. Environmental assessment is one of the accepted ways for achieving sustainable agricultural goals. Hence, life cycle assessment (LCA) is an appropriate way to study the environmental impact of a crop plant producing in its whole life cycle in production systems. Moreover, life cycle assessment (LCA) is an appropriate method for studying the environmental impacts of a crop product throughout its life cycle in production systems. Therefore, this research was carried out with the aim of evaluating the life cycle of irrigated and rainfed wheat productions based on the farm size in Bushehr region in 2016-17. Material and Methods To conduct research, at first, 200 wheat fields were identified which 100 farms belonging to rainfed cultivation in the Genaveh region and 100 farms belonging to irrigated cultivation in the Dashty region were monitored. After data recording, farms in each method were classified into five groups in terms of size level, including very small (-1), small (2-5 ha-1), medium (5-10 ha-1), large (10-15 ha-1) and very large (>15 ha-1). For each impact category, correspond characterization factors were used based on cumulative energy demand (CED), cumulative exergy demand (CexD), greenhouse gas protocol (GGP), IPCC 2013 GWP 100a, ecological footprint (EF), and water footprint (WF) methods in SimaPro8. 2. 3 software. Results and Discussion The findings of this study demonstrated that all impact category of cumulative energy demand (CED), cumulative exergy demand (CexD), greenhouse gas protocol (GGP), IPCC 2013 GWP 100a, ecological footprint (EF), and water footprint (WF) in rainfed cultivation were significantly higher than irrigated cultivation. In addition, the impact category indices associated with the CML-IA non-baseline model, such as global warming 500a, acidification, eutrophication, ionizing radiation, malodorous air, ozone layer depletion 40a, human toxicity 100a, freshwater and marine aquatic ecotoxicity 100a in rainfed cultivation, were significantly higher than irrigated cultivation. Moreover, impact category of heavy metals emitted into the air (Pb, Cd, Zn, and Hg), heavy metals emitted into water (Cr, Zn, Cu, Cd, Hg, Pb, and Ni), nitrate into soil, metals into soil, pesticide into the soil, and emission of NOx, SOx, NH3, dust, COD, phosphorous and nitrogen in the rainfed method was much higher than irrigated cultivation. In irrigated planting method, with increasing farm size from very small to very large, all of the pollutants revealed a decreasing trend, but it was varied in rainfed cultivation, with the largest amount belonging to very small farms. According to the results, it is possible to improve productivity by reducing nitrogen and fuel consumption as well as mechanization of agricultural crops. Based on the findings, it can be argued that farmers in both systems consider economic efficiency in production and are less likely to pay attention to environmental sustainability. It seems that by reducing the government subsidies related to chemical inputs and promoting conservation planting systems, the gap created could be offset to increase economic and environmental productivity in wheat cultivation in the region. Conclusion The variability of these indicators based on farm size level in rainfed cultivation can be due to lower variation in output (yield) and all inputs from very small to very large fields. Therefore, these results show that the share of pollutants in irrigated cultivation is lower than in rainfed cultivation in the Bushehr region. This issue is of great importance from the ecological point of view because the source of non-renewable energies, which are mostly fossil fuels, and the reliance on these resources in the future, is fraught with great risks.

Introduction Due to limitation of water and soil resources resulted from geological and climatic conditions of Iran as well as necessity of self-reliance in infrastructural issues, efficient usage of water and soil resources available in Iran is inevitable. Climatic changes, reduced biodiversity in the region and concerns about food security are regarded as important issues; hence, evaluation of conditions to attain improved crop production seems essential. To investigate yield improvement methods, yield potential and yield limiting factors (climate, soil, water, and genetic factors) should be determined and evaluated in the first step. Simulation models may be used as scaled-up designs of field experiments to overcome limitations such as time and costs. Crop simulation models are mathematical representations of plant growth processes as influenced by interactions among genotype, environment and crop management. Using crop simulation models can be an efficient complement to experimental research. Models are being used to understand the response of crops to possible changes in crop, cultural management, and environmental variables. Crop models use various plant and environmental parameters to simulate crop growth and should be calibrated and evaluated before usage. Materials and Methods SSM-iCrop model predicts phenological stages as a function of temperature, day length. Calculation of phenological development in the model is based on the biological day concept. A biological day is a day with optimal temperature, photoperiod, and moisture conditions for plant development. Leaf area development and senescence is a function of temperature, provide nitrogen for leaf growth, plant density and nitrogen remobilization. To simulate leaf area expansion, the first step is to determine on each day the increase in leaf number on the main stem using the phyllochron (temperature unit between emergences of successive leaves) concept. In this model biomass is estimated as a function of the received radiation and temperature. Daily increase of crop mass is estimated as the product of incident photosynthetic active radiation (PAR, MJ m-2d-1), the fraction of that radiation intercepted by the crop (FINT) and efficiency with which the intercepted PAR is used to produce crop dry mass, i. e., radiation use efficiency (RUE, g MJ-1). Yield formation in the model is simply simulated as total dry matter production during seed filling period plus a fraction of crop dry mass at BSG (as mobilized dry matter). Modeling seed growth rate and yield formation in the current model is based on a modified linear increase in harvest index concept as described by Soltani and Sinclair (2011). The model needs daily weather data, i. e. maximum and minimum temperatures, rainfall, and solar radiation. The model can be run under multiple scenarios/treatments over many years. Results As a result of the SSM-iCrop model parameterization, three early, medium and late maturing cultivars were determined for canola, which their cumulative degree days (GDD) for growth period completion were estimated as 2000, 2500 and 2700 ° C days. After determination of the required parameters, the model was run based on sowing date, management, and meteorological statistics of the region using the data from the papers which were not used for parameterization, so as to validate the model. The average of the simulated data for days to maturity and yield were 222 (days) and 383 (g. m-2), respectively, whereas observed values for this traits were 223 (days) and 359 (g. m-2). Conclusion: Based on the 1: 1 line and statistics of r=0. 87, CV=18% and RMSE=67. 04 (g. m-2) for grain yield and r=0. 97, CV=5% and RMSE=10. 68 (days) for days to maturity, it may be concluded that simulation canola growth using SSM-iCrop model has been satisfactory and indicates accurate estimation of the model parameters, as well as serving as a verification of the model efficiency in prediction of canola yield under climatic conditions of major canola production regions of Iran.