Showing 6 results for Mehrabi
H. Mehrabi Basharabadi,
Volume 12, Issue 44 (summer 2008)
Abstract
Kerman province is the largest producer of greenhouse cucumber and tomato in Iran. This paper calculates the interest rate of return (IRR) and return period of investment (RPI) in vegetable, cut flowers and strawberry in greenhouse and compares them with vegetable grown outdoors. To do the study, a random sample of 309 farmers was selected in the province of Kerman in 2005. Results showed that IRR for vegetable, cut flowers and strawberry in greenhouse was about 20, 14 and 23 respectively, and it was 45/8 percentage per year for vegetable outdoors. RPI for vegetable, cut flowers and strawberry in greenhouse was about 8, 29, and 7 years, respectively. Vegetables Production under greenhouse produces more employment opportunities, has better yields, higher price and efficient use of factors, but it has lower IRR, higher production cost, higher pesticide residue and is more capital intensive in comparison with outdoor production. Improvement of greenhouse credits, enlargement of metal greenhouses, research on yield and development of greenhouses at region 5 are the important policy-making implications of this paper.
M Mehrabi Koshki, D Zafari, B Sharif Nabi,
Volume 13, Issue 47 (4-2009)
Abstract
Recent studies have shown the controlling effects of Trichoderma species and extract of a few plant species of the Brassicaceae family on some phytopathogenic fungi. In this study, using a completely randomized blocks design in the field, controlling effect of biological agents comprising mustard flour, Trichoderma koningii T18, T. virens T59, T. brevicompactum T30, T. harzianum T56, mixture of four Trichoderma isolates, mustard flour + mixture of four Trichoderma isolates and two commercial biological product of Trichodermin B and Subtilin were evaluated against wheat common bunt caused by Tilletia laevis. According to the infection index, all treatments were able to reduce infection percentage and showed significant differences (P<0.01) compared to control (infected with T. laevis without any biological agent) in which heads infection was 43.5%. Treatments of Mustard flour and mustard flour + mixture of four isolates, reduced the disease by 89.9% and 87.4% respectively. Consequently, it seems that wheat common bunt could be controlled by application of non-infected seeds and by treating seeds using mustard flour without using chemical fungicides.
S. Mehrabi, S. Soltani, R. Jafari,
Volume 19, Issue 71 (spring 2015)
Abstract
Since climate has a major impact on dust generation, it is essential to identify the climatic parameters affecting this phenomenon. In this study, climatic parameters including temperature, relative humidity, rainfall, maximum wind speed and direction were selected and their relationship with visibility data and also dust storm days (recorded at meteorological stations) was analyzed on monthly and yearly scales using multivariable linear regression. Results showed that the number of dust storm days has reached 366 days in the last five years. The minimum dust storm days occurred in autumn in all the stations of Khuzestan province including Abadan, Ahvaz, Omidiyeh, Dezful, and Masjed Soleiman and the maximum dust days for Abadan and Ahvaz stations and three remaining stations occurred in spring and summer, respectively. Results also showed that the highest frequency of dust storms in Abadan and Ahvaz stations did not coincide with summer season which has the lowest rainfall of the year. As a result, it seems that the main reason for this difference is the climatic characteristics of dust sources and deposition regions. The occurrence of dust events in the remaining stations in summer time indicated that the sources of dust storms might be local and within the study area. The regression analysis confirmed this issue as the number of climatic parameters which had significant correlations with visibility data increased from 8 to 16 from west to east in the region. Overall, the results showed that with the increasing distance from Arab countries such as Iraq and Saudi Arabia, dust sources were mostly local and provincial.
Mrs Zahra Mehrabi, Dr Hamid Reza Eshghizadeh, Mrs Afsane Nematpour,
Volume 21, Issue 1 (Spring 2017)
Abstract
To determine the nitrate pollution (water, soil, and tubers) in small (< 0.5 ha), medium (0.5- 1 ha) and large (> 1 ha) size of potato fields, this study was conducted in Fereidan region of Isfahan province during growing season of 2014-2015. For this purpose, the amounts of inputs and the tuber yield were recorded in each farm. Also, average nitrate-N concentration in irrigation water, soil and tubers of different potato farms were measured before planting and after harvesting. The results showed that the average soil N-nitrate concentration in small, medium and large size farms were 16.3, 17.4 and 19.9 mg kg-1 before planting and 10.3, 13.3 and 23.3 mg kg-1 after harvesting, respectively. The average N-nitrate concentration of irrigation water in small, medium and large size farms were 36.3, 27.1 and 19.5 mg L-1 before planting and 47.6, 33.1 and 16.4 mg L-1 after harvesting, respectively. At the post-harvest time, NO3-N concentration of irrigation water were below the standard range concentration (45 mg L-1) in the all large farms while 87 % of small and 85% of medium farms had more than standard concentration. The nitrate concentrations of tubers in large-sized farms were lower than others. The tuber NO3-N concentration was affected by potato cultivar. The lowest concentration of nitrate was observed in the late-season potato cultivars (Agria). that might be associated with greater tubers yield.
E. Mehrabi Gohari, H. R. Matinfar, R. Taghizadeh,
Volume 21, Issue 3 (Fall 2017)
Abstract
Typical routine surveys of soils are relatively expensive in terms of time and cost and due to the fact that maps have been traditionally developed and considering their dependence on experts' opinions, updating maps is time consuming and sometimes not economical as well. While soil digital mapping, using soil various models - the Landscape, leads to simplification of the complexity found in natural soil systems and provides users with quick and inexpensive updates. In fact, the model represents a simplified form of the complex relationships between the soil and the land. This study aims to consider inferential model Soil-Land (SOLIM) in mapping and estimating soil classes in Aran area, Isfahan province. For this purpose, the SOLIM model inputs are digital geological and environmental layers of digital elevation model (DEM) including elevation, slope in percent, slop direction, curvature of the earth's surface, wetness indicator, flow direction, flow accumulation, and satellite images of Landsat 8. The seven subcategory of soil in the study area are input data of SOLIM model. Then fuzzy maps were prepared for seven types of soil and final maps of soil prediction were created by non-fuzzy action. Results showed that the SOLIM using environment variables has very high ability to separate soil types in greater detail and soils with different parent materials, geology, climate and vegetation can be separated from each other by this model with a high degree of accuracy. Comparing error matrix shows that the overall accuracy of the map derived from the model SOLIM is 92.36%.
A. Mehrabi, M. Heidar Pour, H. R. Safavi,
Volume 25, Issue 4 (Winiter 2022)
Abstract
Designing an optimal crop pattern and on-time water allocation of water resources along with deficit irrigation are among the optimal solutions to maximize the water economic efficiency index. In this paper, the simultaneous optimization of crop pattern and water allocation are discussed using the deficit irrigation method. The study area is located west of the Qazvin plain irrigation network. The six different levels of percentage reduction of irrigation rate (0, 0 to 10, 0 to 20, 0 to 30, 0 to 40, and 0 to 50%) in three climatic conditions consist of dry, normal, and wet years were compared. The best irrigation scenario was selected for each year, and the results were compared with the existing crop pattern of the same year. The new crop pattern included the main crops of the region and the addition of rapeseed. The objective was to reach the maximum net benefit per unit volume of water by considering the maximum extraction of monthly and annual surface and groundwater. The results showed that the best scenario in the dry year was maximum deficit irrigation up to 20%, in a normal year full irrigation, and a wet year maximum deficit irrigation up to 10%. The improvement of economic water productivity in a dry year was 52.2%, in a normal year 41.5%, and in a wet year is 19.6% compared to the existing crop pattern. The average percentage of annual irrigation supply increases from 64.3 to 91.7% in a dry year, from 70 to 100% in a normal year, and from 77.5 to 97.1% in a wet year. Also, the relative yield of all crops, especially wheat, alfalfa, and sugar beet significantly increases. Therefore, the gravitational search algorithm as an optimization model can be considered in selecting the suitable crop pattern and allocation of surface and groundwater resources concerning economic benefits in irrigation networks management.
