JWSS - Journal of Water and Soil Science

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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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Phosphate sorption by soils is one of the most important processes indicating the buffering power and availability of P for plants. Phosphorus sorption characteristics of eight representative calcareous soil of Isfahan region were evaluated. For this purpose, 3 grams, of < 2-mm soil were equilibrated for 24 hours at 25±l °C in 60 ml of 0.01 M CaCl₂ with varying amounts of P. Sorbed phosphorus was calculated by the difference between P initially added and P remaining in the final solution. Langmuir, Freundlich, Temkin and Van Huay equations were fitted to the sorption data.

 All four equations adequately described the relationship between sorbed and solution P, but the Van Huay model was slightly superior. Some phosphorus buffering indices were calculated from the sorption isotherms. These buffering indices were highly related to each other as well as to soil properties. Clay percent showed the highest correlation with buffering indices (r=0.771 to 0.949) followed by calcium carbonate equivalent (CCE) and cation exchange capacity (CEC). The quantity of P sorbed at standard concentration of 0.3 µg P/ml (SPR) is reported to the amount that satisfies the phosphate requirement of many crops. This parameter was calculated from Van Huay equation and showed a strong correlation with buffering indices (r=0.807 to 0.990) and soil properties such as clay (r=0.960) and CCE (r=0.809) percents. Regression analysis suggested that clay and CCE percents were the most important soil properties for estimating the buffering power and the standard P requirement of the calcareous soil in Isfahan region.

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Soil development and variability of soil properties on different landforms of Central Zagros were investigated. The study area covers two climatic regions including Shahrekord and Chellgerd with mean annual precipitations of 314 and 1224 mm, respectively. In Shahrekord area, the amount of Fe_o (amorphous and organic-bound iron) was higher in surface horizons, whereas, the Fe_d (crystalline, amorphous and organic-bound iron) was higher in the surface soil of well-drained pedons and concentrated in subsoils with high ground water. Smectite increases as chlorite and palygorskite decrease. This might be an indication of Fe-chlorite transformation as a result of the local effects of organic acids, alternate oxidation reduction and hydrolysis intensity of a wetter past climate. Presence of an argillic as well as petrocalcic horizon with sparitic calcite and spherulitic fabric show intermittent and periodic leaching and deposition in Shahrekord area. Furthermore, reduction in sand and gravel content of the soils from mountain toward plains was attributed to the dissolution of carbonates and deposition of alluvium. Lower pH, lower carbonate content and higher pedogenic Fe in surface horizons were prominent in Chellgerd area. Consequently, interstratified chlorite-smectite, decrease of Fe-chlorite in fine clay, increase of smectite, high CEC and absence of petrocalcic horizon show that weathering intensity was higher in Chellgerd as compared to Shahrekord area. Also, papules with concentric fabric, higher Fe_d-Fe_o, and redder hues in buried horizon suggest polygenetic soils. There was some evidence of climatic change in two areas however, time seems to have played an important role in Shahrekord, whereas topography must have been more effective in Chellgerdarea due to higher tectonic activities and unstable landforms which may confirm the formation of the buried horizon and paleosols.

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Due to physiography and weak structure, the pasture soils in Boroojen are potentially degradable. Converting pastures to agricultural land accelerates the degradation processes. A study was conducted in 1999 to show the effects of almost 20 years of farming on originally pasture land on soil physical properties, fertility, and tilth index of pastures in Boroojen region in Chahar Mahal and Bakhtiari Province (central Zagrous). Soil texture, clay content, bulk density, organic matter, saturation moisture percent, cone index, plasticity index, mean weight diameter and aggregate size and distribution, nitrogen, phosphorus, and potassium were measured.

After 20 years of cultivation, bulk density increased about 20% while organic matter decreased by 30%. Cone index was lower in the undisturbed pasture but nitrogen and phosphorus contents were higher compared to the disturbed pasture. The undisturbed pasture contained more larger (> 1 mm) aggregates, while the disturbed pasture had more smaller aggregates. Sustainable use of natural resources will lead to their long term workability, while negligence of conservational practices including appropriate farming management practices will result in the destruction of these resources.

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In order to investigate the best planting time and rice cultivars for the conditions in Khuzestan Province, seven high quality cultivars of rice namely Domsiah, Binam, Ramasanali Tarom, Sang Tarom, Hasansarai, Tarom Mahalli, Daylamani and Anboori were selected and studied in 4 planting dates starting in Mid-May, with intervals of 15 days. The experiment was conducted as a split plot design in randomized complete blocks with 3 replications for 2 years from 1995 in Shavoor Agricultural Research Station. Main plots were planting dates and subplots were allocated to cultivars.

Results of this experiment showed that significant differences existed among planting dates on grain yield only in the second year. Grain yields were different among cultivars in the two years of study. Simple and combined analyses indicated that there were significant interactive effects between planting dates and cultivars. Tiller number was different between planting date and cultivars in the first year. Interactive effect between planting date and cultivars on tiller number was not significant. Maximum grain number in spike obtained early June planting date (76 grains per spike) and lowest grain number in spike obtained early May planting date (28 grains). Among cultivars, Anboori with 152 and Daylamani with 17 grains had maximum and minimum grain numbers in spike, respectively. One-thousand grain weight was maximum in the early June planting date. Among cultivars, Binam and Daylamani had maximum and minimum grain weights, respectively. Highest fertility percentage was obtained in early June planting date compared to other planting dates. Fertility percentage of cultivars depended on temperature at growth stages before and at anthesis, which was early June for all cultivars. Among environmental factors affecting plant growth, temperature was relatively more important than other factors, particularly than the photoperiod. Even under Khuzestan conditions, there is a wide range of temperature levels for rice planting (from early March to early November) however, even this wide temperature range may not be enough to provide favourable conditions for planting all the cultivars.

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To evaluate cold resistance in wheat in laboratory and to find fast and effective methods of evaluation, nine wheat genotypes were studied in three experiments at the College of Agriculture, University of Tehran, Karaj, Iran. Genotypes consisted of four Iranian cultivars, Sabalan, Boulani, Khalij and Naz one Russian cultivar, Bezostaya and four Iranian accessions, 518, 583, 592 and 1255. In experiment 1, genotypes were grown in 10-cm diameter pots and after hardening in the open, their LT50s were determined in cold chamber. Their cytoplasmic membrane stability were also measured at -12°C through electrolyte leakage measurements. In experiment 2, the genotypes were grown in the field to practice hardening in winter then plant crowns were transferred to the lab and their LT50s were determined. Water content of crowns and leaves, sugar content of crowns, and plant erectness were also measured. In experiment 3, water content of crowns and leaves of the genotypes were measured in non-hardened plants.

Cytoplasmic membrane stability, crown water content and crown sugar content of plants showed significant correlations with LT50. Membrance stability had the highest correlation with LT50 (r=0.88). A high correlation was found between crown LT50 of plants taken from field and LT50 from the plants in the lab (r=0.98). It was found that plant water content reduces with cold hardening. Water content reduction was higher in resistant genotypes compared to susceptible ones. There was no significant correlation between crown and leaf water contents with LT50 in non-hardened plants. Bezostaya with LT50=-16.7°C was the most cold resistant genotype and accession 518 with LT50=-8.2°C was the most susceptible genotype, in this study.

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Iran, as the biggest producer of dates, has 25 percent of the world date production. More than 400 varieties of dates have been identified in Iran. Dates have a high nutritional value they contain considerable amounts of sugar, vitamins and minerals. For instance, 2830 kilocalories of energy are obtained from one kilogram of dates. Dates are economically suitable replacements for sugar in bee feeds. However, feeding bees with some varieties, which contain certain amounts of mannose and potassium, are harmful. This investigation was carried out in order to identify the most suitable variety of dates useful for bee feed and to determine its nutritional value as human food. In this study, the dominant varieties of date including Bam Mazafati, Behbahan Kabkab, Booshehr Kabkab, Jiroft Mazafati, Kangoroad, Khanizi, Khasi, Saameran, Shahani, Shahdadi and Zahedi, were collected and analysed. The amounts of moisture, fat, protein, ash, and minerals such as sodium, potassium, and calcium were determined. Also, sugar composition of the above varieties consisting of glucose, fructose and sucrose, was measured. Chemical methods (Lane-Eynon and Shaffer-Somogyi) and high performance liquid chromatography were used for sugar determination.

The results showed that, except for moisture and protein contents, there was no significant difference between fat and ash contents of the samples. Shahdadi and Zahedi had the highest and lowest moisture contents, respectively. Behbahan Kabkab and Shahdadi had the highest and lowest protein contents respectively. Jiroft Mazafati and Saameran had significantly the lowest amounts of potassium and mannose, respectively, while Kangoroad had significantly the highest amount of sucrose, which is use full for bees. Therefore, these three varieties were found to be suitable replacements for sugar in bee feeds, but considering their price, Saameran is recommended as the best feed for bees. On the other hand, with respect to the minerals and sugar contents, Behbahan Kabkab was found as the most nutritious date for human food.

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For Iranian fermented cheese processing and ripening, different lactic acid bacteria (LAB) that affect on the physicochemical properties and hence the organoleptic characteristics of the cheese is used. Determination of physicochemical changes of cheese, particularly, organic acids is of importance. In this study five cheese formulas with five different group of cheese starters were processed and ripened in 8% brine during two months at 12±1 °C. HPLC analysis of organic acids were accomplished, using SCR-101H column with U. V. detector at 214 nm and quantified with high purity standards concerning each organic acid recovery. Pyruvic, orotic, citric, propionic, lactic, butyric and acetic acids were analyzed after 1, 10, 20, 30, 40, 50 and 60 days of processing and storage. Each determined organic acid exhibited a specific profile changes during cheese ripening.

Lactic acid was dominant organic acid in all samples. Total organic acids were increased significantly after 30 days of storage, but decreased up to the end of ripening. The profile changes of organic acids which was similar in all samples with different amounts related to dominant lactic acid with about 80-90% of the total organic acids. The aromatic mesophile group, CH-N-O1(including Lactococci and Leuconostocs) and Lactobacillus casei and also the mixed mesophiles plus thermophile starters group, CH-1 (including Lactobacillus bulgaricus and Streptococcus salivarius ssp. thermophilus) caused a significant decrease in citric acid and increase in acetic and propionic acid in related cheese samples compared with other cheeses (P < 0.01). But cheese containing only thermophiles or the mixed thermophile and mesophile (code 54) revealed a significant increase in butyric acid. In all samples the changes in pyruvic acid content was irregular. The ripening period of cheese samples were determined by the stepwise regression analysis in relation to their exact amount of organic acids.

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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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During the summer of 1998, leaf and pod blight symptoms of bean were observed in Arak, The survey in the following year showed that the disease had an increasing trend in bean-growing regions of Markazi Province. It appeared that more severe losses occurred in fields equipped with sprinkler irrigation system. Symptoms of diseased plants consisted of formation of irregular necrotic lesions on leaves surrounded by yellow halo. Under favourable conditions, these lesions gradually expanded and heavily infected leaves became blighted. The primary symptoms on infected pods were the development of water soaked spots which later turned to dark or reddish blotches. In attempts to investigate the causal agent, two types of a Gram negative bacteria with raised, yellow and translucent colonies were isolated from leaves and pods of blighted beans. All strains produced Xanthomonadin pigment and their inoculation on young bean plants induced disease symptoms similar to those observed under field conditions. Based on morphological, physiological and biochemical properties, the predominant pathogenic type was identified as Xanthomonas axonopodis pv. phaseoli. However, the other strain with the same properties, but capable of producing melanin pigment in nutrient media, was assigned to X. axonopodis pv. phaseoli var. fuscans.

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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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This paper studies the structure of cost and production of rice using cross section data from rice farming in Guilan in 1997. A translog cost function is specified for this purpose and estimated, using Iterative Seemingly Unrelated Regressions for both the short and the long run where all factors are taken to be variables. The results of the study are as follows:

1. Neither in the short-run nor in the long-run is the possibility of technical substitution among the factors of production strong.

2. Own and cross price elasticity of demand for inputs are positive but less than one, hence limited substitutability among inputs is possible as the result of a change in input prices.

3. As the structure of production of rice in Guilan exhibits increasing returns to scale, increased allocation of land to the production of rice could result in a lower price of the product.

4. Inputs are not homogeneous, therefore, not all producers are faced with the same price for the same input. Nevertheless, the cost of production has been lower for those farmers who have paid a higher price for an input. Therefore, the higher price for inputs is more than that compensated by the quality of each input in the production process.

5. Due to the inelasticity of the demand for rice with respect to prices, a large price increase is required to stimulate farmers to allocate more resources to the production of rice.

6. Since the possibility of substitution among inputs is limited, a large increase in relative prices is required in order to change the structure of rice production.

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Probable Maximum Precipitation (PMP) is the maximum possible amount of precipitation which could occur in a gauging station, a region, or in a watershed. Probable maximum precipitation is usually estimated by two general methods: the first is synoptic method in which short period (hourly) meteorological parameters such as dew point, wind speed and air pressure are used. The second is statistical method which is based on the statistical analysis of the 24-h maximum precipitations. In this study, the amount of 24-h PMP was estimated by Hershfield, Bethlahmy and modified Bethlahmy methods using date obtained from meteorological and Ministry of Energy over 15 or more years.

 The results showed that there exist large differences between statistical and synoptic methods however, there are rather smaller differences between Bethlahmy and synoptic methods. For modified Bethlahmy method, the results were multiplied by a coefficient of relative humidity. Then the calibrated 24-h PMP values were estimated for all meteorological stations of Iran and a contour map of 24-h PMP for the country was developed.

Results showed that a minimum value of 24-h PMP (110 mm) occurred in the central part of country and a maximum amount (260 mm) was found in both south and north parts of Iran.

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A Complete Randomized Block design was used to study the total protein efficiency (TPE) in Iranian Kilka and Peruvian Anchovy fish meals. Six isoenergetic (3200 kcal ME/kg) and isonitrogenous (18.5% CP) diets based on corn with six samples of fish meal (No. 1, 5, 6 steam processed, 2, 4 flame processed Kilka fish meal and No. 3 Peruvian Anchovy fish meal) were formulated and fed to Lohman male chicks from 7 to 42 days of age. Feed consumption and weight gain were measured weekly. Total protein efficiency and feed conversion (FC) were calculated and statistically analyzed.

The highest TPE values in fish meals obtained over the period of 7-28 days and significantly differed (P< 5%) among Kilka and Peruvian fish meals. With the exception of sample No. 5, the highest values of TPE obtained in the case of steam processed and the lowest obtained the case of flame processed Kilka fish meals. The TPE value of Peruvian fish meal was approximately equal to the average of the two types of processed Kilka fish meals. The orthogonal and nonorthogonal comparison of TPE and feed conversion (FC) in Kilka fish meals, regardless of the type of processing, with the same values in Peruvian Anchovy fish meal did not show any significant differences (P> 5%). With the exception of sample No. 5, the highest final weight of chicks obtained with steam processed Kilka fish meal. In general, TPE values in Kilka fish meals were variable when compared to Peruvian fish meal and TPE of steam processed Kilka fish meal was better.

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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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Many sediment transport equations have been developed for estimation of the river sediment materials during the past four decades. There are significant differences in the results from these equations when applied to compute sediment transport for a specific river. Therefore, application of an equation for estimation of a river sediment load is not an easy task. In this study, 12 important sediment transport equations including Meyer-Peter and Muller, Einstein, Bagnold, Engelund and Hansen. Toffaleti, Ackers and White, Yang, Van Rijn, Wiuff, Samaga et al, Beg and Fazel were tested against the measured field data of four major Khuzestan rivers, namely, the Karoon, the Dez, the Karkheh, and the Maroon. For accurate results and rapid computation, a computer program was developed for this purpose. Over 490 measured data from the gauging stations of these rivers are selected. Using these data, the hydraulic parameters and the bed material of the gauging stations are determined.

The results of the computer program are analyzed and compared with the measured data. The results from this study show that those equations which are based on the energy exchange of the flow, are generally in good agreement with the measured data for Khuzestan Rivers. From these equations, the Engelund and Hansen’s equation generally predicts satisfactory results for the all gauging stations except for the Maroon River gauging station. And finally if the sediment load computed by the Beg’s method is multiplied by a factor of 0.1, the results approximately match those obtained from the Engelund and Hansen’s method.

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The emitter discharge is affected by parameters such as pressure, irrigation water temperature, manufacturer’s coefficient of variation, and emitter clogging. In order to study the effects of irrigation water temperature on emitter discharge and to determine the discharge-pressure variations and manufacturer’s coefficient of variations, an experimental trickle irrigation system was designed and studied in the greenhouse, College of Agriculture, Isfahan University of Technology. Since the sensitivity of different emitters to water temperature variations is variable, four different, widely used, types of Iranian emitters including in-line long-path emitter, gun emitter, pressure compensating emitter, and double-chamber tube were used. Each emitter was evaluated under 14 different irrigation water temperature treatments ranging from 11 to 43.5°C.

 The results showed that in general as water temperature increases, the emitter discharge increases linearly in all types, except for the pressure compensating emitter in which the discharge decreases linearly. The emitter uniformity, absolute emission uniformity and Christiansen uniformity coefficient parameters were affected by emitter discharge variations. For each type of emitter under study, the changes in manufacturer’s coefficient of variations due to irrigation water temperature were different. The manufacturer’s coefficients of variations at a water temperature of about 20°C for double-chamber tube, in-line long-path emitter, gun emitter and pressure compensating emitter were equal to 5, 7, 13 and 22 percent, respectively. Moving from gun emitter to the double-chamber tube and finally to the in-line long-path emitter, the sensitivity to irrigation water temperature decreased. Sensitivity to pressure variations decreased in the order of gun emitter, double-chamber tube, in-line long-path emitter, and finally pressure compensating emitter.

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Nitrogen is usually the most limiting nutrient for crop production. Thus, N fertilizer is widely used by farmers. Moreover, Mn deficiency in some calcareous soils of Iran with high pH has been reported. Therefore, the addition of nitrogen and manganese to achieve the optimum yield is necessary. The objective of this study was to evaluate the effect of N and Mn applications on the availability of some soil nutrients under wheat (Triticum aestivum L.), corn (Zea mays L.), and spinach (Spinacia oleracea L.) plants in greenhouse conditions. In a factorial test, five levels of N (0, 50, 100, 200 and 400 mg/kg soil as NH₄NO₃) and three levels of Mn (0, 15 and 30 mg/kg soil as MnSO₄) in a completely randomized design with four replication were applied. Corn, wheat and spinach varieties were sc₇₀₄ Falat and Spinacea spp., respectively. After eight weeks, total N content and DTPA-extractable Mn, Fe, Zn and Cu of soil were measured.

 The results indicated that N and Mn applications increased Mn-extractable of soil in three cultures but didn’t affect the soil total N. Nitrogen application in corn increased available Fe in soil. Mn application decreased extractable Zn and Cu of soil in wheat and soil extractable Cu in corn.

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This manuscript shows the findings of a research that investigated the effects of trainings on the members and the employees of the poultry cooperatives in Tehran Province on the performance of these cooperatives. To analyze the data, 2, correlation coefficient, one way-analysis of variance, and Duncan Test were used. The results of the study showed a positive and statistically significant relationship between training of members and performance of cooperatives. The more the trainings were related to type of occupation or responsibility, the larger were the effects on the cooperative performance. Cooperatives with more specialized top managers, offered more training to their members. Compared to cooperatives with more training, the members had less participation in increasing their investment.

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Agricultural insurance is one of the appropriate ways to overcome the risk in agricultural production and to increase farmers’ income security. In this study, the influence of wheat insurance, as personal-free insurance, and sugar beet insurance, as group-forcible insurance, on farmers’ risk attitudes in Fars Province were investigated as a case study. Data were collected using stratified multi-stage cluster sampling method and interviews in the years 1375-1376. The sample included wheat and sugar beet farmers in three different climates including Mediterranean, warm sub-desert and cold mountainous in Fars Province. Results of estimating risk aversion coefficients of farmers, using Safety First Rule (SFR), showed that sugar beet forcible insurance along with giving inputs, mechanization services, lookout of farms by sugar plants led to continuous insurance purchase by farmers in consecutive years. Therefore, sugar beet farmers tended to welcome insurance and the effect of insurance on their risk aversion coefficients was positive. However, discontinuity of insurance purchase by wheat farmers in consecutive years and farmers’ lack of confidence in insurace system caused the influence of insurance on wheat farmers’ risk aversion coefficient to be insignificant. Thus, sugar beet insurance type is closer than wheat insurance type to one of the main aims of agricultural insurance system, which is increasing farmers’ tendency to take risks.