Showing 6 results for Abdolahi
M. Abdolahi Ezzatabadi, B. Najafi,
Volume 10, Issue 2 (summer 2006)
Abstract
In this study, at first, different models for measuring hedge ratios in futures and options markets were introduced. Then, the models were applied to a sample of 300 Iranian pistachio producers. The results showed that hedge ratios in pistachio futures and options markets, on average, were in a range of 0.22 to 0.99. When pistachio yield is unpredictable, options market is preferred to futures market. But in certain conditions, futures market is preferable. The results also showed that debt to asset ratio had a positive effect on hedge ratio, but bank loan effect was negative.
A Ephtekhari, M Farahpour, H Arzani, J Abdolahi,
Volume 13, Issue 47 (4-2009)
Abstract
Species which were grazed by livestock and wildlife in range sites and the portion taken by each animal were the subject of this study. Two sites occupied with Scariola orientalis (Boiss.) Sojak and Artemisia sieberi Besser and another with Aellenia subaphyla (C.A.Mey.)Aellen and Artemisia sieberi were selected for the study. These sites were already established by Yazd Research Center for Agriculture and Natural Resources. Sites should be covered with similar vegetation (72% similarity), as much as possible indeed. One site, by the name of Kalmand, is a protected area and is exclusively grazed by Iranian gazelle, while the other, Jadehdehshir, by sheep and goat. Results of the study show that the selection of species is the same by these animals. Both are interested in the following species: Artemisia sieberi, Scariola orientalis, Bromus tectorum L, Stipa barbata Desf. , Noaea mucronata (Forsk.) A schers.et Schweinf, and Launaea acanthodes (Boiss.)o.Kuntze. On the contrary, species such as Acantholimon scorpiurs (Joub. &Spach) Boiss, Astragalus albispinus L were not taken by the animal for their woody stems and thorny branches. Fresh and non woody parts of the plants were grazed by both types of animal. Similarity between grazing behavior of wildlife and livestock in Yazd province shows that wildlife feed requirement should be seriously taken into account when grazing capacity of rangelands is to be evaluated.
N. Moradi, M. H. Rasouli-Sadaghiani, E. Sepehr, B. Abdolahi,
Volume 16, Issue 62 (Winte - 2013 2013)
Abstract
Organic acids can affect phosphorus (P) sorption. In order to evaluate the effect of citric acid and oxalic acid on phosphorus sorption characteristics in calcareous soils, five different soil samples (0-30 cm) were collected in West Azerbaijan province. Soil samples (2.5 g) were equilibrated with solutions of KH2PO4 containing 0 to 20 mg P l-1. Five mM organic acids were added to each tube and sorbed P was calculated. The sorption data were fitted to Langmuir, Freundlich and linear equations. The results showed phosphorus sorption data were well described by the Freundlich and linear equations. The average values of Kf (distribution coefficient), n and equilibrium buffering capacity (EBC) of linear equation in citric acid treatment were reduced to 29, 12 and 17 percent, respectively and for oxalic acid reduced to 43, 27 and 14 percent, respectively. Maximum sorption was reduced significantly by oxalic as compared to citric acid. Standard phosphorus requirement (SPR) was decreased by 57 % as a result of organic acids additions compared to control condition. It is concluded that organic acids additions to soils containing more calcium carbonate and high amount of clay can decrease P sorption.
A. Abdolahi Arjenaki, A. A. Fadaei Tehrani,
Volume 19, Issue 71 (spring 2015)
Abstract
Plant parasitic nematodes, especially root knot nematodes, cause damage to most of agricultural products, and many efforts have been done to control them. In recent years, application of industrial waste and wastewater sludge as organic fertilizers in agriculture has been increased. To investigate the effects of sewage sludge on root knot nematode pathogenicity in tomato, different weights of sewage sludge (0, 4, 8, 15 and 25% of sludge in the soil) in soil were added as a completely randomized design with six replications. Analysis variance and mean comparison of growth indices of plants showed significant effects of treatments. For example, means of stem length of plants increased in soil with more amount of sewage sludge. This relationship was also observed in other indices and nutrients elements. So using sewage increased nitrogen, phosphorous, calcium and magnesium in tomato shoots inoculated with nematodes while the change of potassium was very small. Application of sewage sludge decreased the number of galls, egg-masses and eggs in egg-mass of root knot nematode.
H. Siasar, T. Honar, M. Abdolahipour,
Volume 23, Issue 4 (winter 2020)
Abstract
The estimation of reference crop evapotranspiration (ETo) is one the important factors in hydrological studies, irrigation planning, and water resources management. This study attempts to explore the possibility of predicting this key component using three different methods in the Sistan plain: Generalized Linear Models (GLM), Random Forest (RF) and Gradient Boosting Trees (GBT). The maximum and minimum temperature, mean temperature, maximum and minimum humidity, mean humidity, rainfall, sunshine hours, wind speed, and pan evaporation data were applied for years between 2009 to 2018. Using various networks, the ETo as output parameter was estimated for different scenarios including the combination of daily scale meteorological parameters. In order to evaluate the capabilities of different models, results were compared with the ETo calculated by FAO Penman-Monteith as the standard method. Among studied scenarios, M1 covering the maximum number of input parameters (10 parameters) showed the highest accuracy for GBT model, with the lowest RMSE (0.633) and MAE (0.451) and the maximum coefficient of regression (R = 0.993). Air temperature was found as the most sensitive parameters during sensitivity analysis of studied models. It indicated that accuracy and precision of temperature data can improve the results. Application of the GBT model could decrease the time consumed to run the model by 70%. Therefore, the GBT model is recommended for estimation of ETo in the Sistan plain.
M. Paritaghinezhad, H.r. Kamali, S. Jamshidi, M. Abdolahipour,
Volume 27, Issue 2 (Summer 2023)
Abstract
According to the effects of climate change on evapotranspiration and using of water resources, climate change prediction is vital due to water resources management improvement and decreasing damages of drought. The first rank of mango production in Iran belonged to Hormozgan province and the most amount of mango produced in Minab plain. In the present study, the amount of evapotranspiration of mango plants was calculated with FAO Penman-Monteith from 1985 to 2020 using meteorological data at Minab station. The evapotranspiration values of the plant were estimated from 2021 to 2100 with two optimistic and pessimistic scenarios using the last version of CMIP (CMIP6), atmospheric-ocean general circulation models, and performing statistical deviation corrections by the Python software. The results showed that the values of annual evapotranspiration will increase by 0.31 and 1.23 mm on average in the optimistic and pessimistic scenario, respectively in the future due to the increase in annual temperature.
