Azimi M.,Gorgan University of Agricultural Sciences and Natural Resources |
Heshmati G.A.,Gorgan University of Agricultural Sciences and Natural Resources |
Farahpour M.,Research Institutes of Forests and Rangelands |
Faramarzi M.,Isfahan University of Technology |
Abbaspour K.C.,Eawag - Swiss Federal Institute of Aquatic Science and Technology
Ecological Modelling | Year: 2013
Rangeland areas in the arid and semi-arid regions of Iran suffer from high grazing pressure and periodic droughts. These regions account for 85% of the national total rangeland area and make an important contribution to country's economy. To determine how to better manage this important resource, we developed a rangeland-livestock model using the Soil and Water Assessment Tool (SWAT). The model was tested in the river basin located in Tehran and Semnan Provinces of Iran. Sagebrush species of Artemisia sieberi Besser and Artemisia aucheri Boiss (covering more than 38% of the total rangeland areas in Hablehroud river basin) was chosen and some of their characteristics were used to add the necessary plant growth parameters to SWAT landuse database. In combination with the SWAT model, the Sequential Uncertainty Fitting Program (SUFI-2) was used to calibrate and validate the eco-hydrological model of the watershed based on river discharges and forage production of sagebrush species, taking into consideration historic grazing management. The model predicted well rivers discharges at eight hydrometric stations (P-factor 0.6-0.9; R-factor 0.85-1.5) as well as the sagebrush yield in three ecological zones across the basin. We found that the current grazing intensity was more than twice as much as the region's capacity. Based on some scenario analysis for water and grazing management we showed that through proper water management, we could obtain an average increase of about 40% in sagebrush forage production, while through grazing management an average increase of 30% could be obtained. This shows the region's nutritional capacity could substantially increase. The analytical framework used in this study could be applied to other arid and semi-arid environments for the assessment of forage production and livestock management to achieve a more sustainable food production. © 2012 Elsevier B.V.
Afshar R.K.,University of Tehran |
Chaichi M.R.,University of Tehran |
Assareh M.H.,Research Institutes of Forests and Rangelands |
Hashemi M.,University of Massachusetts Amherst |
Liaghat A.,University of Tehran
Industrial Crops and Products | Year: 2014
Milk thistle is a recognized medicinal plant cultivating for production of silymarin and oil. Responses of milk thistle to deficit irrigation and organic soil amendments were studied in a 2-year field experiment. Three levels of irrigation regimes including normal irrigation (I100), moderate deficit (I75) and severe deficit irrigation (I50) and two sources of soil amendments consisted of vermicompost (VM) and poultry manure (PM) plus no amendments comprised nine treatments laid out in a factorial pattern in a randomized complete block design. Moderate and severe deficit irrigation resulted in 7 and 27% seed yield reduction, respectively. Among yield components, number of seeds head-1 showed the highest sensitivity to deficit irrigation followed by number of heads plant-1 while seed weight remained stable. As irrigation deficiency intensified, Irrigation water use efficiency followed an increasing trend. Among the two soil organic amendments, only PM significantly improved the seed yield where plots amended with PM produced 8, 12 and 17% higher seed yield under I100, I75 and I50, respectively. Application of PM also improved irrigation water use efficiency. Implementation of deficit irrigation improved silymarin content of the seeds; however, silymarin yield declined due to the lower productivity in stressed conditions. Oil yield was also adversely affected by both moderate and severe deficit irrigation and reduced by 9 and 32%, respectively. Application of soil amendments had no significant effect on silymarin and oil content of the seeds, but PM improved silymarin and oil yield due to its beneficial effect on seed yield. The results of this study indicated that milk thistle can be grown under moderate deficit irrigation (saving 25% of irrigation water) and amending soil with PM can improve the yield and minimize the negative impact of drought stress. © 2014 Elsevier B.V.
Keshavarz Afshar R.,University of Tehran |
Chaichi M.R.,University of Tehran |
Rezaei K.,University of Tehran |
Asareh M.H.,Research Institutes of Forests and Rangelands |
And 2 more authors.
Agronomy Journal | Year: 2015
Milk thistle (Silybum marianum L. Gaertn.) seeds contain relatively high amounts of edible oil. Influences of irrigation regime (full irrigation, moderate deficit, and severe de cit irrigation) and organic fertilizers (vermicompost [VM] and poultry manure [PM]) on the oil content and fatty acid (FA) composition of milk thistle seed were evaluated in a field trial. Averaged across treatments, seed oil content was 27% whereas unsaturated FAs constituted 78% of the oil composition. Linoleic acid (41.4%) and oleic acid (35.1%) were the most abundant unsaturated FAs whereas palmitic, stearic, arachidic, and behinic acids were major saturated FAs. Oil content was significantly in uenced by irrigation regimes, but not by organic fertilizers. Severe deficit irrigation reduced oil content by 7.4% compared with full irrigation. Deficit irrigation had a minor e ect on the FA composition of milk thistle oil where total unsaturated fatty acids (UFA) was lower in stressed plants. The application of soil organic amendments did not induce significant changes in unsaturated fatty acids but reduced the content of saturated ones which totally imposed positive effects on oil quality of milk thistle. According to the results, it seems that milk thistle has potential to be considered as an oil seed crop in low-input agricultural systems in arid and semiarid areas and moderate de cit irrigation can be implemented without deleterious effects on its oil content and quality. © 2015 by the American Society of Agronomy, 5585 Guilford Road, Madison, WI 53711. All rights reserved.
Salehi Shanjani P.,Research Institutes of Forests and Rangelands |
Jafari A.,Research Institutes of Forests and Rangelands |
Calagari M.,Research Institutes of Forests and Rangelands
New Zealand Journal of Crop and Horticultural Science | Year: 2013
Genetic differentiation between co-occurring crops and their wild relatives will be greatly modified by crop-to-weed gene flow and variation between human and natural selective pressures. In this paper, the pattern of population differentiation within and among the wild and cultivated populations of Agropyron desertorum in Iran, with respect to both total protein profiles and phenotypic traits, is measured and compared. A total of 180 A. desertorum individuals from 14 wild and four cultivated populations were included in the study. The levels of genetic diversity in cultivated populations were similar to those in wild populations (mean percentage of polymorphic loci [PPL] = 53.26% versus PPL=51.66%, and mean expected heterozygosity [He] = 0.154 versus He=0.165). Neighbour-joining cluster analysis showed that wild populations and cultivated populations were not separated into two groups. The coefficient of genetic differentiation (Fst) between a cultivar and its wild progenitor was 0.060. For the 14 wild populations, a significant genetic differentiation among populations was found using AMOVA analysis (30% of total genetic variation resided among populations). © 2013 The Royal Society of New Zealand.