JWSS - Journal of Water and Soil Science

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This experiment was conducted to estimate genetic parameters of some of the important traits of silkworm in two populations, namely, Japanese and Chinese lines in Iranian Silkworm Rearing Co-Natanz. Based on single pair mating method, 9 male moths mated with 9 female moths and then raised under standard environmental conditions. Performance of 30 progenies of each pair was recorded.

Heritability coefficients (parental full-sib method) of single cocoon weight (CW), shell weight (SW), pupal weight (PW) and shell ratio (SR) were estimated to be 0.209±0.123, 0.228±0.129, 0.174±0.109 and 0.044±0.042 in the Japanese race and 0.196±0.1l8, 0.234±0.132, 0.159±0.103 and 0.00, in the Chinese race, respectively. Genetic and phenotypic correlation between CW & SW were 0.645 & 0.957, CW & PW, 0.962 & 0.982, CW & SR -0.351 & 0.123, SW & PW, 0.496 & 0.871, SW & SR, 0.265 & 0.457, PW & SR, -0.446 & 0.169, respectively. Selection, based on heritability coefficients of single cocoon weight and shell weight, can be applied successfully to genetic-gain in this trait. Based on correlation coefficients between traits, selection for shell weight can be applied successfully to improve other traits such as single cocoon weight and shell ratio.

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In order to study the parasitoid flies of Sunn pest in Isfahan, this research was conducted during the years 1997-1998. The results indicated that the dominant species of parasitoid fly is Phasia subcoleoptrata L. This species has two generations per year and over winters as pupae in soil under the shrubs of aestivation and hibernation places of Sunn pest and remains there until the following spring. The adults of the first generation of this parasitoid emerge from the pupae before the Sunn pest migrate to the grain fields and parasitize on the Sunn pest at the time of migration. About 6-8 days after the flies lay eggs in the body of Sunn pests, parasitoid larvae hatch from the eggs and grow in the body of their host. Larval period of parasitoid lasts about 15-20 days and then they fall on to the soil and pupate. In the laboratory, the length of pupal period for males and females is 17 and 18.5 days, respectively, for the first generation. Flies of the second generation of the parasitoid parasitize the fifth nymphal instar and the new adults of the Sunn pest.

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Flood is one of the catastrophic events that has attracted the hydrologists’ attention. In this research one of the important flood indices, i.e. maximum-daily mean-discharge, was determined for several western Iran watersheds, namely, in the catchments of Gamasiab, Qarasou, Saimare, Kashkan, Sezar and Abshineh. Daily data were prepared from stream-gauging stations and a 30-year concurrent period was selected.

 Flood frequency analysis was performed using HYFA and TR computer programs and optimum distributions were chosen by goodness of fit tests. Extreme flow values having different return periods of 2, 5, 10, 25, 50, 100, 500 and 1000 years were calculated. Modeling was done with regional analysis using multiple regression technique between maximum-daily mean-discharge and physiographic characteristics of the basins. The most important parameter for the selection of the model was the adjusted coefficient of determination while significant level, standard error and observed discharger vs. computed discharge plot acted as controlling parameters. Finally, different models with different parameters were selected from power, exponential, linear and logarithmic forms. The results showed the power model to be the best among the four types. The main channel length, drainage density and time of concentration were the most effective parameters on flow. After analyzing the errors, it appeared that increasing the return period would cause an increase in the model error. At 1000-year return period, the error reached 32.2%.

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The main sources of cadmium in soil-plant continuum in amounts that might present a hazard are liquid and solid wastes of sewage sludge, farm manures and fertilizers. In the southwest of Iran (Khuzestan Province) over 50,000 ha of land is under sugarcane (Saccarum officinarum) cultivation and more than 80,000 ha will be under sugarcane by the end of the year 2000. In these sugarcane fields, about 400 kg ha^-1 diamonium phosphate (DAP) and 400 kg ha^-1 urea are applied annually. There is no data available to show the fertilizers impact on soil, water and plant contaminations in Iran with respect to cadmium. The objective of this research was to compare the extractable cadmium of virgin soils with that of soils under sugarcane.

 Four sugarcane growing stations viz. Haft-tapeh, Karoon, Shoeibieh and Ghazali with cultivation histories of 36, 20, 2 and 1 year, respectively, were selected. In each site, along a transect soil samples from 0-30 cm of both furrows and ridges of cultivated soils and of virgin soils were collected. Electrical conductivity (EC), pH, clay and organic carbon contents, CI and Cd of 101 soil samples were measured according to standard methods. Results showed that increasing either EC or CI increased Cd concentration with its maximum in virgin soils and its minimum in furrows.

 Results also indicated a slight decrease in the Cd content of cultivated soils.

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In this study 130 honeybee colonies in 4 locations (Damavand, Tehran, Qum and Karaj-Savojbolagh) were sampled to determine the phenotypic correlations among 9 morphological and 3 production traits. The morphological traits were length (FL) and width (FB) of fore wing, cubital index (CI), length of hind leg (HL), length of probosics (LP), slender index (SI), length (WL) and width (WT) of wax mirror, distance between wax mirror (WD), index of wax mirror (IW) and corbicular area (CA). The production traits were honey yield (WH), pollen gathering (WP) and wax: production (WW). Data were subjected to analysis of variance, phenotypic correlations, stepwise regression and path coefficient analysis. Results of phenotypic correlations demonstrated that correlations between FL with FB (0.65), WL (0.361), WT (0.261), HL (0.555) and LP (0.257), WH with WP (0.300), WW with WH (0.560) and CA with WH (0.234) were significant (P≤0.01). FB with WH (r=0.204) was also significant but there was no significant correlation between CA and WP. Results of stepwise regression and path coefficient analysis showed that whereas morphological traits were settled as independent variables, much of the corresponding changes in production traits remain uninterpreted. In spite of the significant correlations among several morphological and production traits, body measurements alone are not suitable criteria to select colonies for high productions of honey, pollen and wax.

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Nitrogen fertilizer application for corn (Zea mays L.) based on available N of soil can decrease the need to N fertilizer and, consequently, reduce the risk of environmental pollution, especially that of groundwater and drinking water. The objectives of this study were i) determining soil N0₃-N critical level at 4 to 6 leaf stage, ii) to study soil nitrate distribution, iii) determining N rate required for maximum corn grain yield, iv) measuring soil residual nitrate nitrogen after harvesting, and v) using hand chlorophyll meter to evaluate N status of corn. The experiment was conducted under field conditions in Bajgah and Kooshkak research stations (Fars Province) in 1996 using a split plot randomized complete block design with four replications. Main plots were control, 60, 120, and 180 kg N ha^-1 as urea. At 4 to 6 leaf stage each main plot was divided into two sub-plots and N was applied at 60 kg N ha^-1 rate to one sub-plot and the other sub-plot was left as control.

 Results showed that critical soil N0₃-N level at 4 to 6 leaf stage in 0-30 cm depth for 90 percent relative yield in Bajgah was 12-14 and for Kooshkak was 8-10 mg kg^-1 soil. The highest coefficient of determination between corn grain yield and soil N0₃-N in 0-30 cm depth for Bajgah was in furrow sample and for Kooshkak was in furrow and shoulder composite sample. In both sites, maximum corn grain yield, with 15.5% moisture content, was about 14 mg ha^-1 that was obtained through the application of 120 kg N ha^-1 as preplant plus 60 kg N ha^-1 as sidedress which is about 1/2 of the application rate used by local farmers. The highest residual soil N0₃-N after harvesting was 24 and 18 and the lowest was 2.6 and 3 mg kg^-1 soil for Bajgah and Kooshkak soils, respectively. When maximum corn grain yield was obtained, chlorophyll meter reading at the middle of leaf blade at dough stage, was 49 for both sites. It seems that N fertilizer application rate by local farmers is excessive.

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The effect of N levels and planting densities on quantitative and qualitative characteristics of grain yield in grain sorghum (cv. Kimia) was studied in summer 1998 at Kushkak Agricultural Research Station, Shiraz University. The experiment was a spilt plot with 4 replications in which 4 levels of planting densities (7.7, 10, 15.4, 20 seeds m^-2) were applied as main plots and 4 levels of N (0, 40, 80, 120 Kg N ha^-1) as subplots.

 N application rates up to 120 kg N ha^-1 increased grain yield (7240 kg ha^-1), but due to increased planting density (5336 kg ha^-1) the highest yield obtained from 15 seeds m^-2. Interaction of N and planting density was also significant. Application of 80 kg N ha^-1 and highest planting density produced 8702 kg ha^-1 of grain. Different grain yields in different levels of N and planting densities were due to increased number of grains per basic branches of panicle and increased number of panicle per m^-2. The trend of variation of crop growth rates (CGR) was similar to the trend of grain yield. Nitrogen application increased grain protein contents but planting density had no significant effect on grain protein. Phenolic compounds (tannins) decreased with increasing N application and with decreasing planting density. A negative correlation was observed between increased N content and increased phenolic compounds.

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In order to determine the relationships among the different traits of onion and to study the direct and indirect effects of these traits on bulb and seed yield, an experiment was conducted in 1998 at the research farm of Isfahan University of Technology. Results showed that phenotypic and genotypic correlations were similar and bulb weight showed the highest and lowest coefficients of correlation with bulb diameter and number of days to emergence, respectively. Results of stepwise regression analysis showed that leaf width at 25% of its length from the neck, leaf length, and leaf dry weight were the best estimators for leaf area bulb diameter, bulb length, plant height and number of days to maturity were the most important determining characters for bulb yield variation. Number of fertilized florets was the best determinator of seed yield and bulb weight, while diameter and volume were the best describing characters for the number of meristems on the basal plate. Path-coefficient analysis revealed that bulb diameter showed the highest direct positive effect on bulb yield and the indirect effect of plant height through bulb diameter on it was of prime importance. Number of fertilized florets per plant and number of inflorescence per plant through the number of fertilized florets showed the highest direct and indirect effects on seed weight, respectively.

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Nitrogen is usually the most limiting nutrient for crop production. Manganese deficiency in some calcareous soils of Iran has been reported. The objective of this study was to evaluate the effect of N and Mn on the growth and chemical composition of spinach (Spinacia oleracea L.) under greenhouse conditions. The experiment was conducted in a soil from Chitgar series (Fine-loamy, carbonatic, thermic, Calcixerollic Xerochrepts). Treatments consisted of factorial arrangement of five N rates (0, 50, 100, 200 and 400 mg kg^-1 as NH₄NO₃) and three Mn rates (0, 15 and 30 mg kg^-1 as MnSO₄) in a completely randomized design with four replications. Plants were allowed to grow for 60 days and a hand-held SPAD-502 chlorophyll meter was used to evaluate leaf chlorophyll status at harvest.

 Results showed that N and Mn application increased shoot dry weight, N and Mn concentrations and total uptake, Mn:Fe ratios and chlorophyll readings, significantly. Nitrogen increased concentrations and total uptake of Zn, Cu and total uptake of Fe in plants, but decreased Fe concentration. Addition of Mn decreased Fe and Zn concentrations in spinach but increased total uptake of Fe and Cu. When maximum dry matter was obtained, the chlorophyll meter reading was about 40. A similar study should be carried out under field conditions before the N and Mn fertilizer recommendations for spinach can be made.

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This experiment was carried out to study the effect of ionophore drugs (Salinomycin, Lasalocid and their combinations) on the performance of broiler chicks. Also their relationships with methionine (three levels) were evaluated. 1215 one-day-old commercial broiler chicks (Arian) were divided into 81 groups, 15 chicks per group, and tested in a completely randomized design with a 3×3×3 factorial experiment. Three drug types with three levels (0.0, the recommended level and 1.5 times the recommended level) of drugs and three levels (0.0, 0.1% and 0.2%) of supplemental methionine were used.

 The results indicated that the effect of sex on plasma cholesterol and triglyceride, percentage of bone ash and percentage of abdominal fat was significant (P<0.0l). Drug type had no effect on the characteristics under study. Drug level influenced percentage of bone ash, percentage of eviscerated carcass, and percentage of abdominal fat significantly (P<0.0l), (P<0.01) and (P<0.00l), respectively. Also methionine level influenced cholesterol and triglyceride (P<0.0l) significantly. Interaction effect of drug type and drug level on plasma cholesterol and triglyceride was significant (P<0.05). Interaction effect of drug and methionine level on cholesterol and triglyceride was significant (P<0.0l). The results showed that levels of this drug influenced carcass composition and also supplemental methionine had no influence on the modulating effect of these drugs on carcass composition.

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In this research, the presence of metalaxyl residues was studied in field-grown cucumber. Two different formulations of metalaxyl were used in the experiments. In the first experiment, cucumber plants were sprayed once and repeatedly by Ridomil-MZ 72 WP at 2.5 g/litre. In the second experiment, single and double applications of metalaxyl granule 5G were carried out at 5 g/m². Leaves and fruits were sampled at different times after each treatment and analyzed for metalaxyl residues by HPLC.

In leaf samples from single sprayed plots, metalaxyl residues declined rapidly following the treatment and more than 50% of the residues disappeared in the first two days, whereas in the leaf from single granule-applied plants, the residues increased during the first three weeks and then declined. Metalaxyl residues in cucumber sampled from single sprayed-plots were at a high level during the first three days after the spray and declined below the MRL (0.5 mg/kg) on the 7th day. In granule-applied plots, the residues increased during the first 7 days and the level below the limit was recorded 20 days after application. Residual values for plants sprayed with suspension showed a faster dissipation rate than granulated treatment. Metalaxyl recovered after three times of spraying and two times of granular application did not show any toxic accumulation of residues in fruit.

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Micronutrients availability including that of Zn is critical for optimum growth of plants. Zinc availability in calcareous soils of Iran is relatively low due to the presence of a large amount of CaCO₃ and high pH levels. Overapplication of phosphorus to soils may also cause P-induced Zn deficiency. The objective of this experiment was to evaluate the effect of phosphorus and zinc application on the growth and chemical composition of corn (Zea mays L.) under greenhouse conditions. Treatments consisted of a factorial combination of 5 levels of P (0, 25, 50, 100 and 200 µg P/g soil as KH₂PO₄) and 3 levels of Zn (0, 5 and 10 µg Zn/g soil as ZnSO₄. 7H₂O) in a completely randomized design with 3 replications. Plants were allowed to grow for 60 days and then cut at the soil surface.

 Results showed that P and Zn applications increased top dry weight. Applied P increased P concentration and total uptake in plants, but decreased Zn concentration and had no effect on Zn uptake. Zinc application decreased P concentration of com but increased Zn uptake and concentration. The P: Zn ratio in plants increased with P application but decreased with Zn addition. Application of P and Zn increased Fe concentration in plant but decreased Mn concentration and had no effect on Cu concentration. Prior to making any fertilizer recommendations, more research is required to precisely evaluate the response of com to P and Zn applications under field conditions.

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The objective of this investigation is to measure pectinesterase activity by a simple method. The assay is done at 25°C. Oranges were obtained at a local supermarket in winter. They were peeled and 5 gr sections of the peeled tissue were homogenized in 10% NaCl and 0.5 M phosphate buffer in a homogenizer. The homogenates were centrifuged at 3500 rpm for 20 min. The supernatants were collected, their pH levels were raised to 7.25 using NaOH and the reaction was monitored at 485 nm in a spectrophotometer. The activity of pectinesterase was expressed as micromoles of methanol released per minute.

The results show that this method is reliable, sensitive, and capable of measuring pectinesterase activity of as low as 0.05 unit. The assay method proposed is a very useful analytical tool for the determination of the activities of pectinesterase.

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Pseudomonas syringae is a phytopathogenic bacterium with a wide host range. The biology of this bacterium consists of two phases. The first phase is the indication of disease on the host plant which generally appears in the form of necrosis on the aerial parts of plant (pathogenicity phase). The second phase is a rapid multiplication of bacteria on the aerial surface of the plant without inflicting any defense response (epiphytic phase). In this study, the impact of pathogenic virulence genes of aggress, dsp, ice, cor and hrp genes in the epiphytic process of Pseudomonas syringae on resistant and sensitive varieties of tomato is examined. The population dynamism of bacterial colonization on the root, stem and leaves was studied.

The results indicated that the hrp genes system (hypersensitive reaction and pathogenicity) in Pseudomonas syringae pv. tomato, P. s. pv. syringae and P. s. pv. phaseolicola and the coronatine gene system in P. s. pv. tomato are necessary for colonization on both host and non-host plants. The mutants isolates of hrp and cor compared with wild isolates could colonize at a lower level on all parts of the plant. In contrast, the ice (Ice nucleation), aggress (Agressivity) and dsp (disease specific) gene systems had no significant impact on the epiphytic colonization of P. s. pv. syringae. However, under in vitro conditions no significant difference was observed among the wild type isolates and their mutants in king B medium in the bioscreen machine. It is concluded that the lower multiplication of P. syringae mutants in planta is due to the plant-bacteria interaction.

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Pathogenicity and virulence of entomogenous fungus, Verticillium lecanii, was studied on the pea aphid, Acyrthosiphon pisum. Vertalec, a commercial product of V. lecanii, was evaluated under controlled conditions. Second instar nymphs were inoculated with conidial suspensions at concentrations ranging from 10⁴ to 10⁸ conidia/ml, and sterile distilled water (containing wetting agent) as control, then caged on cutted alfalfa stems. Each concentration was replicated three times with 30 aphids treated per replicate. Temperature, relative humidity and photoperiod were maintained at 23±1 °C, %97±3, and 16:8 (L:D), respectively. Aphids were monitored daily over 12 days for mortality and nymph production. All newborn nymphs and dead aphids were removed daily.

Vertalec significantly increased aphid mortality (mean mortality because of mycosis increased form %45.55±6.93 at 10⁴ conidia/ml to %95.55±4.45 at 10⁸ conidia/ml). The LC₅₀ value for pathogen was 5.l4×l0⁴ conidia/ml. LT₅₀ values for 10⁵, 10⁶, 10⁷ and 10⁸ conidia/ml were 10, 8, 6.5 and 5 days, respectively. At 10⁴ conidia/ml LT₅₀ value was not determined at experimental period. R_o values significantly decreased with increasing conidial concentration (mean R₀ altered from 28.l5±5.38 in control to 5.15±1.81 at 10⁸ conidia/ml). Results indicated that vertalec can be an effective agent against pea aphids. Further studies are recommended for its evaluation under natural conditions.

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Bolting in onion reduces yield and quality of bulbs. To control bolting chemically, a glasshouse experiment was conducted using Texas Early Grano which is widely cultivated in subtropical areas of Karman Province. In this research, Paclobutrazol (0, 1000, 2000 mg/lit), ethephon (500, 1000, 2000, 3000, 4000 mg/lit), cycocel (500, .1000 mg/lit) and mixtures of ethephon and cycocel were sprayed on onion plants prior to vernalization. At harvest time, morphological characters (bolting percentage, shoot length, shoot dry weight, bulb maturity index) and biochemical characters (chlorophyll a, b and total in shoots, reducing sugars and soluble proteins in roots, bulbs and shoots) were recorded. Paclobutrazol reduced bolting, reducing sugars, soluble proteins and shoot length but increased leaf chlorophylls, proteins, sugars and bulb weight with no effect on shoot dry weight. Although ethephon reduced bolting, shoot growth, sugars, proteins and leaf chlorophyll and increased maturity index, sugars and proteins in bulbs, it had no effect on bulb yield. Cycocel increased bolting, sugars, proteins, chlorophylls and dry weight in shoots but had no effect on shoot length, leaf chlorophyll, sugars and protein in roots and bulb weight. Cycocel also reduced sugars and protein in bulbs. Mixtures of cycocel and ethephon reduced bolting, leaf chlorophyll, shoot length and dry weight but had no effect on bulb yield and other characters measured.

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To estimate the relationship between honey yield and some of the morphological characters, five queen-daughters from each of 30 queen-mothers were studied. The queen-mothers were selected randomly from the apiary of Research Center of Animal Science and Natural Resources in Isfahan Province. Summer honey yield was measured from the difference of honey comb before and after honey extraction while fall honey production was calculated from area of sealed honey combs. Morphological characters were recorded using a stereodissecting microscope fitted with a calibrated micrometer reticule according to Ruttner’s procedures. The mean of honey yield for a year was estimated to be 10.05 kg. Phenotypic correlations between yearly honey production and summer and fall honey productions were estimated to be 0.49 and 0.88, respectively, while the correlation between summer and fall honey yields was low (0.019). There were significant correlations between summer honey yield with cubital-b index, tibia length and forewing width (0.28, 0.27 and 0.25, respectively). Also there were significant correlations between metatarus width with total and fall honey yields (0.22 and 0.23, respectively). Genetic correlations between metatarus length and cubital index with summer honey yield were negative (-0.75 and -0.45, respectively). It may be concluded that due to the high correlation between summer honey production and total honey yield, one could improve yearly honey production by selecting on the basis of summer yield of colonies. Among morphological traits, metatarus length, forewing width and cubital index could be used in the breeding plan in order to increase honey yield.

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Phosphorus (P) and iron (Fe) are essential nutrients for plants. Iron availability is low in calcareous soils of Iran due to the excessive amounts of CaCO₃ and high pH. Overfertilization of P fertilizers may also decrease Fe availability. The objective of this study was to evaluate the effect of P and Fe on the growth and chemical composition of corn (Zea mays L.) under greenhouse conditions. Treatments consisted of a factorial arrangement of P rates (0, 40, 80, 120 and 160 mg kg-1 as KH₂PO₄) and Fe rates (0, 2.5, 5 and 10 mg kg^-1 as Fe EDDHA) in a completely randomized design with four replications. Plants were grown for 8 weeks in a loamy soil, calssified as Chitgar series (fine-loamy, carbonatic, thermic, Typic Calcixerepts). Results showd that P application up to 80 mg kg^-1 increased corn top dry matter. Corn P concentration and total uptake increased by P application but decreased by Fe application. Application of Fe up to 5 mg kg^-1 increased dry matter but decreased it at higher rates. Concentration and total uptake of Fe increased by Fe application but decreased by P application. Zinc and copper concentrations decresed significantly when P was added. Manganese concentration increased at 40 mg P kg^-1 but decreased at higher rates. Iron application decreased zinc and manganese concentrations but had no effect on copper.

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In this research, sunflower oil that was extracted and refined at Shiraz Narges Oil Company was packed in four different containers, namely, clear PET (polyethylene terephtalate), yellow PET, yellow HDPE (high density polyethylene), and metal can. Samples were kept at ambient temperature in the shelf exposed to normal light for a period of 1 year. Peroxide values were determined at 45-day intervals and TBA and anisidine values were measured at 0, 6 and 12-month periods. In order to determine the effect of artificial light, some samples in PET and HDPE containers were kept in a wooden box equiped with four (20 w) fluorescent lamps and the peroxide values of the samples were determined. Light transmittance properties of the packaging materials were measured using a spectrophotometer over a wavelength range of 350 nm to 800 nm. The data indicated that the greatest variations in peroxide, TBA and anisidine values were observed in samples in HDPE containers (significantly different at 5% level) kept under normal light and ambient temperature for a period of 1 year. It was also shown that the shelf life of sunflower oil in HDPE container was less than 6 months while for the other packaging materials it was more than one year. Samples exposed to artificial light indicated that the highest peroxide values belonged to samples in clear PET while those in yellow PET proved to have the lowest. Finally, PET container proved to be the most suitable container for sunflower oil followed by metal can. Yellow PET with the lowest transmittance percentage (350-800 nm) and peroxide value (when exposed to 20 w fluorescent lamp) could be substituted for clear PET. HDPE container proved to be unsatisfactory for sunflower oil due to high oxidation rate.

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Small honeybee (Apis florea) is one of the common species in Iran. Apis florea lives in southern Iran and plays an important role in the polination of plants in this region. In a series of studies during the years 1997-1998, the genetic populations of the Iranian small honeybee and the effects of geographic and climatic conditions on the morphological variation and separation of Iranian small honeybee were investigated. For this purpose, 400 samples of worker bees from 40 colonies from 26 cities in 9 provinces were collected and twelve morphological characters were measured, using Ruttner method (1978). To determine geographical and climatological variables, average values collected by synoptic stations and other meteorological stations of Iran Meteorological Organization were used. The principal components analysis was used in the statistical analysis of the data obtained. The results show that there exist two distinct groups of small honeybee populations in Iran. Southwest of Iran hosts a class of bigger bees forming one distinct group while southeast of Iran hosts smaller bees forming the second group. Latitude has a positive correlation with size of body, wings and legs. Amount of precipitation has a nagative correlation with size of body, wings and legs. Temperature, wind speed. relative humidity, freezing days and other parameters did not show any correlations with size of body. The results from this research proved that the more northern areas with higher altitudes and more precipitation have bigger honeybees. This finding is in accordance with the Bergman law about other animals.