JWSS - Journal of Water and Soil Science

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The population parameters of sweet potato white fly, Bemisia tabaci (Genn.) (Hom.: Aleyrodidae), which is an important pest of cotton fields, were studied during 2001. The infected leaves containing nymphs and pupae were collected from Darab, Qom, Saveh, Gonbad, Gorgan, Varamin, Garmsar, Orsoiieh (Kerman), and Shooshtar cotton fields. Experiments were conducted in a growth chamber under 24±.2^ºC, 55%±3RH and 16:8 (L:D) photoperiod on cotton, a Gossypium hirsutum L. (Varamin 76 variety). The newly emerged populations of each locality were released into a large cage set on cotton plants separately. Population parameters of 40 mated females were calculated for each local population. Intrinsic rates of increase (r) for Darab, Qom, Saveh, Gonbad, Gorgan, Varamin, Garmsar, Orsoiieh and Shooshtar were 0.0401, 0.0719, 0.0750, 0.0602, .0682, 0.0774, 0.0876, 0.0751 and 0.0988, respectively. Doubling times (DT) were 17.26, 9.63, 9.24, 11.51, 10.16, 8.94, 7.91, 9.22 and 7.083 days, respectively, and mean generation times (T_c) were calculated to be 28.72, 28.9, 28.74, 28.3, 28.68, 27.53, 29.12, 28.21 and 26.84 days, respectively. Other population parameters such as finite rate of increase (λ), intrinsic birth rate (b), intrinsic death rate (d), and stable age distribution were also calculated. The results revealed that there were significant differences between population parameters in local populations. The parameter (r) was the least in Darab and the greatest in Shooshtar populations.

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The host-stage preferences of alfalfa black aphid, Aphis craccivora, by parasitoid wasp, Lysiphlebus fabarum, were studied under two trials under growth chamber conditions (55±5 %, R. H., L:D 14:10 H. and Tem. 20 ±2^° C ). In the first trial, all stages of aphid in equal ratios, and in the second trial, variable ratios of 5:15, 15:15 and 15:5 of 3rd and 4th instar nymphs were used for parasitisation. The objective was to identify the most preferred stage of aphid for parasitism by Lysiphlebus fabarum. The results showed that 3^rd instar nymphs of alfalfa black aphid were the most preferred stage with 38.75% of parasitism. Whereas 4^th instar nymphs and adults had 23.75% and 21.25% parasitism, respectively. The first instar nymphs were not parasitized at all. In the second trial with variable ratios of 3^rd and 4^th instars of alfalfa black aphid, parasitism of 3rd instar in ratios 25, 50 and 75 percent of total population were 35.9, 55.74 and 79.6%, respectively, while those for 4^th instar nymphs were 20.36, 44.26 and 64.09%, respectively. So there was a positive preference for 3^rd instar and a negative preference for 4th instar nymphs.

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A 3×4 factorial experiment was conducted for 45 days to determine the effects of diets containing different levels of protein and fat on growth of fingerlings Beluga (Huso huso L.1758). Twelve different diets were formulated with 3 levels of protein (45,50 and 55) and 4 levels of oil including fish oil and sunflower oil (0.5 ,4 , 8 and 12). 1260 Beluga fingerlings with an initial body weight (IBW) of 2.2 gram, after adaptation to the experimental conditions, were selected and stocked randomly into 36 fiberglass tanks (100 water volume) at 35 fish per tank, and fed on experimental diets for 45 days. Two ways analysis of variance showed that the percentage of body weight increase (%BWI), specific growth rate (SGR),protein efficiency ratio (PER), food concumpsion ratio, and productive protein value (PPV) content were significantly (P<0.05) affected by different protein and fat levels. Fishes fed on diets No.3 (containing 45% protein and 14 % lipid) and No.8 (containing 50% protein and 17 % lipid) showed the highest increase in body weight percentage, the best specific growth rate, protein efficiency ratio, and lowest food concumption ratio. Besides, the highest productive protein value was observed in diet No.2 (45% protein and 10.5% lipid) and diet No.3 (45% protein and 14 % lipid).Comparison of chemical composition of examined fish corps indicated a significant difference in their protein and lipid contents (P<0.05). However, the composition of the diet, revealed no significant changes on the dry matter and ash content of the body. Based on the findings of the present study 45-50% dietary crude protein is recommended for the optimum growth of Beluga fingerling. Moreover, the rate of needed lipid for optimum growth of fingerling range is from 14 to17 percents.

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In addition to farm operations, power tillers in Iran are also engaged in load and passenger transportation. Inspite of their noise and adverse effects on power tiller drivers and bystanders, they have not been adequatly investigated. The initial survey in the present investigation on a 13-hp power tiller at 2200 rpm engine speed revealed that its noise was 92 dB(A), compared to the standard limit of 85 dB(A) which is disappointing. The test site was prepared according to international standards and the noise signals emitted from the system were measured and analyzed in time and frequency domains for audio frequency range (20 – 20000 Hz). The results showed that the noise intensity was higher by 7.74 to 10.75 dB(A) for the microphone position at driver’s ear compared to the bystanders position and that the engine speed played a great role in noise generation for power tiller. This is because the noise increases up to 8.5 dB(A) with engine speed variations. Finally, the power tiller prediction models of sound pressure levels at driver’s ear and bystanders were determined using the experimental data.

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Floodwater Spreading (FS) plays an effective role in improving soil fertility, ground water recharge, vegetation cover, and desertification control. The soil fertility might increase as a result of a suitable suspended sediment material transferred to the downstream by flood events. To define a relevant FS method which increases the efficiency of the FS projects, it is necessary to study the quality and quantity of transported sediment material, spatially and temporarily. In this research, this subject was investigated by taking soil samples throughout 13 FS stations for physical and chemical analysis over 5 years. Within each of the 13 selected stations in the three first flooded dikes, soil sampling was carried out using random-systematic method. The total Nitrogen, absorbed Phosphorous and Potassium, and Organic Carbon of each sample were analyzed. Because of the abnormality of data, nonparametric test was adopted to compare means. All stations were classified into three groups using cluster analysis method. Based on the results, the variations of fertility factors are irregular between the dikes and amongst years. This could have been affected by several factors such as the quality and quantity of diverted flood, the characteristic of FS sites, and irregularity of sediment material deposited on the sites. Despite the low quality of soil fertility prior to the construction of these stations, in general, FS has a considerable role in improving the soil fertility. However, desirable objectives may be achieved in long term through occurrence of diverse flood events and suitable maintenance of the stations.

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The main scope of this research is evaluation of Soil Conservation Service Procedure in derivation of initial abstraction of precipitation in watershed scale. For this purpose Dalaki watershed which is located in south east of Iran was selected then by using hec-hms and GIS models and a number of observed rainfall runoff events some parameters like CN of watershed ,K and X of Muskingam method and initial abstraction of precipitation were calibrated through two different search algorithm of univariate and Nelder & Mead methods. The early results of this research indicated the superiority of Univariate search algorithm over the Nelder&Mead method both in calibration and also validation processes. Then using calibrated CN and Initial abstraction parameters which were derived through Univariate search algorithm, the factor between initial abstraction and potential retention of surface runoff (S) in each of sub basins were estimated. 0.13, 0.43 and 0.19 were derived as the above mentioned factor respectively for Minimum, Maximum and mean of the above mentioned factor in this step of the research which showed an acceptable compatibility to the offered factor of 0.2 by SCS. Then in rainfall runoff modeling process of this watershed SCS offers a reliable method of initial abstraction estimation.

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Integrated management of watershed basins depends on deep knowledge of basic concepts such as the arrangement of lands and their uses. Location and distribution of agricultural land use help to balance water resources in the watershed basins. In this research with the help of satellite images of Landsat 5 and 8, and the method of maximum likelihood classification algorithm, land use types of water, barren areas and salt lands, and irrigated agriculture were studied in the Urmia watershed in the years 2010 and 2013.Then applications of modis images and product Urmia watershed land cover for years 2010 and 2012 were compared and finally modis and Landsat land covers in 2010 were compared. Results showed that the area of irrigated farmlands of Urmia basin has increased in the years between 2010 and 2013; while, the water zone has declined. Comparison between modis and landsat in 2010 showed that modis can estimate irrigated lands and water zone better than barren areas. The kappa coefficient for years 2010 and 2013 in Landsat images are 0/77 and 0/87, respectively.

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