Journal of Agricultural Science and Technology
Volume:14 Issue: 5, Sep 2012

In the present study, shearing properties of sugar cane stems were determined at five moisture content levels (46, 54, 62, 70 and 78% wb), three shearing speed (5, 10 and 15 mm min-1) and at ten positions on the stem. For measuring the shearing forces, the stems were severed by using a computer aided cutting apparatus. Decrease in moisture content of stem from 78 to 46% wb led to 16.3 and 16.7% decrease in the shearing strength and specific shearing energy, respectively. The maximum and average values of shearing strength of the two moisture contents were found to be 3.482 and 3.1 MPa, and the specific shearing energies were 112 MJ mm-2 and, 102.6 MJ mm-2, respectively. Both the shearing strength and the specific shearing energy were found to be higher in the lower region of the stem due to structural heterogeneity. Results showed that with the increase in shearing speed from 5 to 15 mm min-1, shearing strength and the specific shearing energy increased 3.2 and 4.6%, respectively. The results of ANOVA indicated that effects of the mentioned factors were significant at 1% probability level. The shearing model assessment revealed that the third order polynomial model exhibited the best performance in fitting with experimental data and, by using this model, a significant correlation was found between shearing strength, specific shearing energy, and moisture content (R2= 0.989 and SE= 0.001). Also, a significant correlation was found between shearing strength, specific shearing energy, and shearing speed by using Hoerl model (R2= 0.989 and SE= 0.005).

Application of feed pellets in animal and aquatic farming industries has grown because of both the physical and the nutritional benefits it provides. Development of feed pellets manufacturing industry is also considerable. Steam conditioning process, which plays an important role in pelleting production, includes heating feed particles, adding moisture, and mixing the mash. Pellets cooling and drying processes are also involved in heat transfer phenomena. In this study, thermal conductivity of feed pellets was determined at different temperatures ranging from 25 to 85°C and moisture contents of 11.8 to 18.2% wb. It was measured by the transient technique using the line heat source method assembled in a thermal conductivity probe. It turned out that decreasing moisture contents from 18.2 to 11.8% (wb) produced non-linear reduction in thermal conductivity. The average values of thermal conductivity changed from 0.1509 to 0.2143 W m-1 °C-1 at different moisture contents. Tests conducted on two pellet size categories (based on nominal diameter) revealed a significant difference in thermal conductivity between these categories. The thermal conductivities of the first category (minor than nominal dia.) appeared to be 8.5% higher than those of the second category (superior to nominal dia.). Average values of thermal conductivity changed from 0.1538 to 0.2333 W m-1 °C-1 for the first category and from 0.1235 to 0.2456 W m-1 °C-1 for the second category (in 25°C). In addition, some empirical models were developed to express thermal properties as a function of moisture content and temperature.

Bacteria of the genus Azospirillum are well known as plant growth promoting rhizobacteria. The ability to synthesize phytohormones is considered one of the most important mechanisms to promote plant growth and is widely distributed among plant-associated rhizobacteria.The most important phytohormone produced by Azospirillum is the auxin indole-3-acetic acid, with the L-tryptophan as the precursor. In the present study, we evaluate the capacity of eight Azospirillum strains isolated from rice and wheat, to produce in vitro auxins using plant exudates. Our results show that isolates produced auxins in tryptophan free media, but, generally, the amount produced increased when the tryptophan concentration increased. Some plants root exudates had a similar effect to tryptophan for the auxin production. In this sense, bean, rice and canola root extracts produced, respectively, 93.3%, 96.2%, and 88.31% more auxin than L-tryptophan. Azospirillum sp. isolate A3 had the maximal capacity to produce auxin. Therefore, the effect of cell free supernatant was studied on rice root development. Statistical analysis did not show any significant difference between root number and dry weight of the treated and control seedlings. However, significant differences were observed in root length and wet weight at α=0.01 and α=0.05, respectively.

Limitations of water and nitrogen in soil usually restrict plant growth. The objective of this study was to evaluate the effects of different amounts of supplemental irrigation at different growth stages and application of different rates of nitrogen fertilizer on grain yield and water productivity of wheat cultivars. A field experiment was conducted in the agricultural research station of Shahrekord University, Iran, for 2 years. The experiment had a split-split plot design with 3 replications. Five irrigation treatments occupied the main plots, two wheat cultivars were the sub-plots, and three levels of nitrogen were allocated to the sub-subplots. Seed yield and water productivity increased with the total amount of water available to plants. Water productivity increased linearly with increasing additional irrigation from the jointing stage to the seed filling stage, in both years. However, the rate of grain yield and water productivity in irrigation treatment at the jointing stage was greater than the other irrigation treatments. Both wheat varieties showed positive response to supplemental irrigation treatments and nitrogen fertilizer, but the rate of grain yield and water productivity was greater in Azar2 cultivar. Additional nitrogen fertilizers also increased seed yield and water productivity in bothyears. Generally, the combination of supplemental irrigation at jointing stage and application of 100 kg nitrogen ha-1 have important roles in the improvement of seed yield and water productivity of Sardari wheat cultivarunder semi arid region.

Interleukin-1β (IL-1β), the prototypical pro-inflammatory cytokine, is produced by macrophages following exposure to bacterial products. Its role is to act upon several cell types at the site of infection to stimulate the production of pro-inflammatory molecules that will cause increase in vascular permeability. Therefore, IL-1β regulates the initiation and development of acute inflammation that may have a role in mammary gland defense during mastitis. Single nucleotide polymorphisms (SNPs) in the 5''-flanking region of this gene can modulate IL-1β function. The aim of the present study was to discover and analyze SNPs in promoter region of IL-1B gene in cattle (Bos taurus). The 5''-flanking region of IL-1B gene was screened by single strand conformation polymorphism (SSCP) in Holstein and Iranian local cattle breeds (50 local and 50Holstein). A total of 4 distinct SSCP patterns were observed, which further revealed 5 novel SNPs upon sequence analysis in Iranian local breed. From the SNPs identified in this region, polymorphism at nucleotide position -534 was found to lie in the vicinity of potential GATA and ZNF transcription factor binding sites. The SNPs identified at -383 position was shown to be present within the putative ETS factor and also core sequence of CARE transcription factor. Two SNPs at positions -534 and -340 were found within the EBF binding site. The SNPs identified in the 5''-flanking region of IL-1B gene may serve as potential candidate genetic marker(s) for disease resistant traits in cattle.

Microwave-assisted hydrodistillation (MAHD) at three levels of microwave power (180, 360, and 540 W) and the traditional hydrodistillation (HD) were applied to obtain essential oils from Bunium persicum Boiss. (Black Zira). MAHD at 540 W started much earlier than that of HD (4 min vs. 38 min, respectively). By the time the extraction of essential oils started with HD, almost 50% of the total essential oils (2.15%, w/w yield) had been extracted with MAHD at 540 W. Analysis of the essential oils using gas chromatography-mass spectrometry showed that γ-terpinene (28.16-31.13%, w/w), cuminaldehyde (24.85-29.20%), ρ-cymene (14.67-16.50%) and limonene (6.13-8.28%) were their main constituents, with a similar composition both after HD and MAHD extraction. The antioxidant activity (reported as IC50) of essential oil extracted by HD was 9.31 mg ml-1 and those of MAHD at 180, 360, and 540 W were 8.62, 8.79, and 6.45 mg ml-1, respectively. Microwave irradiation did not cause any adverse effect on the antioxidant activities of the extracted essential oils, therefore, it can be used as a good alternative method to obtain essential oils from B. persicum.

The main objective of this study was to investigate the effect of enterococci isolated from traditional Lighvan cheese on the quality of Iranian UF white during ripening. Four samples of cheese were provided from four different cheese production units in Lighvan region. Strains of enterococci in these samples were isolated by standard microbiological methods and selective medium of Kanamycin Esclin Azide Agar and then identified by biochemical methods. In the second stage of research, the effect of adding isolated enterococci in traditional Lighvan cheese on the quality of Iranian UF white cheese was investigated in a 60-day period. Addition of Enterococcus spp. did not significantly (P> 0.01) affect the pH and percentage of pH 4.6-Soluble nitrogen/total nitrogen. In the cheese produced with E. faecalis and E. faecium strains, lipolysis rate was higher and flavor properties were improved. Moreover, results of measuring percentage of soluble nitrogen at pH 4.6 and urea polyacrylamide gel electrophoresis indicated an increase in proteolysis rate in the cheese containing E. faecalis and E. faecium strains compared to the control cheese. Furthermore, the highest percentage of non- protein nitrogen was observed in the cheese containing E. faecium. In conclusion, the results showed the positive effect of the E. faecalis and E. faecium on secondary proteolysis during ripening. The proteolytic activity displayed by some enterococcal strains may contribute to cheese ripening and flavor development. Because of these interesting metabolic traits, enterococci have been proposed as part of defined starter culture combination for UF white cheeses.

Many parameters affect essential oil yield and chemical composition of aromatic plants. For obtaining the highest quantity and quality of essential oil, it is necessary to know the proper methods of drying and distillation. The aim of this research was to investigate the influence of drying and extraction methods on the yield and chemical composition of the essential oil of Eucalyptus sargentii. The fresh leaves of Eucalyptus sargentii, cultivated in Kashan (central region of Iran), were collected in the middle of spring and dried by five different drying sun-drying, shade-drying, and oven-drying at 30, 40 and 50°C. The essential oils of every treatment were obtained by hydro-distillation in three replication. In addition, the essential oil of shade-dried sample was obtained by two other distillation methods, namely, water- and steam-distillation and direct steam-distillation. The oils were analyzed by capillary GC and GC-MS. Statistical analysis showed significant difference between oil yield (w/w) of the shade-dried sample (3.39%) compared to oven-dried at 40°C (2.92%), sun-dried (2.66%), oven-dried at 30°C (2.59%) and oven-dried at 50°C (2.30%). The oil content of the shade-dried sample obtained by hydro-distillation (3.39%) was higher than those of the water and steam distillation (2.89%) and steam distillation (1.35%). Twenty-three components were identified in the oil of E. sargentii in the different drying methods, including 1,8-cineole (57.9-65.8%) and α-pinene (11.3-28.3%) as main components. Twenty-four compounds were characterized in the oils of different distillation methods, including 1,8-cineole (61.2-66.6%) and α-pinene (19.7-28.3%) as the major compounds. Among the different drying methods, shade-dried samples produced the highest oil yield and 1,8-cineole content, while in different distillation methods, hydro-distillation produced the highest oil yield, but the highest percentage of 1,8-cineole was obtained by water and steam distillation.

Tobacco (Nicotiana tabacum L.) is an important industrial crop and its seeds contain significant amounts of oil. The extraction of oil components using solvent at high pressure, or supercritical fluid (SCF), has received much attention. In the present study, statistical analyses showed that the average extraction yield of seed oil of five tobacco varieties using SFE was 9.33%, which was higher than Sonication (7.75%) and DGF (Deutsche Gesellschaft f_r Fettwissenschaft) standard method B-I5(87) (8.48%), but lower than Soxhlet (13.72%). Also, fatty acids profile of each extracted oil was determined by gas chromatography. Various saturated and unsaturated fatty acids such as lauric (C12:0), myristic (C14:0), palmitic (C16:0), palmitoleic (C16:1), stearic (C18:0), oleic (C18:1), linoleic (C18:2), linolenic (C18:3) and eicosanoic (C20:0) acids were observed in the extracted oils.

Increasing the nutritional value of bread is important since the enriched product can be used for special target groups such as developing countries or special diets. Wheat germ, a highly nutritive part of wheat kernel, is a by-product of milling factories and has the potential to be used for food supplementation. The main aim of this research was to supplement flat bread (Barbari) with wheat germ and to study the quality and staling of the resultant bread. Therefore, processed (heated at 150°C for 45 minutes) and raw wheat germs were added at the rates of 0, 5, 10 and 15% (w/w) in bread recipe, as separate treatments. Using a Farinograph, it was found that the dough made with raw germ had less water absorption, lower consistency, and shorter stability time. Modeling of the data showed that increasing the germ level had negative correlation with bread volume and softness. Such effects were enhanced when raw germ was used. It was found that addition of germ could not delay bread staling; however, it had positive effects on its taste and general acceptability, particularly when 15% processed germ was used.

The main postharvest problems of persimmon in Iran are severe softening and disease incidence on the fruits during storage. Therefore, delay in softening and/or control of diseases result in the storage life extension of persimmon fruit. The strategy of induced disease resistance in plants by biotic and abiotic treatments is an attractive method for controlling diseases. Salicylic acid (SA) is a well known natural inducer of disease resistance in plants. In this study persimmon fruits cv. Karaj were treated at harvest with SA at 0 (as control), 1 and 2 mM and the quality parameters of the fruit were measured during 3 months of storage at monthly intervals. The most noticeable effect of postharvest SA application on stored persimmon fruit was the reduction of disease incidence at 2 mM concentration, while 1 mM SA failed to control diseases. Results showed that SA did not affect TSS, titratable acidity, soluble tannin content, and fruit firmness. Also, SA could not suppress ethylene production compared to the control. SA treatment at 2 mM concentration reduced postharvest disease incidence of persimmon fruit by inducible defense mechanism, being suitable for increasing postharvest life of the fruit.

Grass pea (Lathyrus sativus L.) is a crop used for both animal and human consumption. Recently, ICARDA has developed new grass pea lines with the objectives of improving its yield potential and adaptability. The objective of this study was to investigate grain and forage yields stability of several ICARDA released grass pea lines by using additive main effects and multiplicative interactions (AMMI) and site regression genotype plus genotype-by-environment interaction (SREG GGE) model. Fourteen grass pea advanced lines were evaluated at three research stations located in semi-warm regions in Iran, during 2005-08 crop seasons. The combined ANOVA showed that forage and grain yields were significantly affected by environment (E), genotype (G) and interactions of G×E. The partitioning of the sum of squares indicated that E accounted for 85% and 91% of the total (G+E+GEI) variation for forage and grain yields, respectively; whereas, G and GEI accounted for 4 and 11% for forage yield and 2 and 7% for grain yields, respectively. Using AMMI and GGE biplots, the lines identified as stable and high grain yielding were Sel.474, Sel.669, and Sel.686, while for forage yield the lines were Sel.474, Sel.678 and Sel.669. Kermanshah and Gachsaran were selected as favorable test environments for grass pea grain and forage yield ME trials, respectively.

Pyramiding genes related to grain quality and resistance through marker assisted selection (MAS) is an important approach in rice breeding programs. Marker-assisted selection can be used for monitoring the presence or absence of these genes in breeding populations and can be combined with conventional breeding approaches. This study is a part of cultivar development program in Iran through integration of conventional breeding with marker assisted selection. Crosses between two high yielding transgenic lines carrying an insect resistance gene (cry1Ab, from Bacillus thuringiensis) with a local aromatic variety were made followed by selection for incorporation of insect resistance and aroma (fgr) genes in desirable single F2 plants. Finally, plants homozygous for aroma and carrying cry1Ab genes with good agronomic performance were identified. Further analyses are underway on these plants in F3 generation. These plants promise to develop new aromatic Bt rice lines through integration of classical and molecular breeding in the near future in Iran

In order to locate the QTLs for plant height, peduncle length, and heading date, a set of 107 wheat doubled haploid (DH) lines derived from the cross Fukuho-komugi× Oligoculm was grown during the growing seasons of 2004 and 2005. A total of 36 QTLs were identified based on composite interval mapping (CIM) approach. All detected plant height QTL’s were stable over the two years. QTLs located near RhtD1 (chromosome 4D) and in the Xta556-RhtB1 interval (chromosome 4B) accounted for, respectively, 40.1% and 28.9% of plant height variation in 2004 and 30.7% and 26.36% in 2005. The other two QTLs identified for plant height were located near Xcfd53 and Xwmc25a loci on chromosome 2D. The results of composite interval mapping indicated that all detected QTLs for peduncle length were coincident with plant height QTLs. Of the most important heading date QTLs, the only stable one over years was located in the Xcfd53-Xbarc168 interval on chromosome 2D and accounted for 34.05% and 31.9% of heading date variation in 2004 and 2005, respectively. The Xbarc168-Xgwm484 interval (LOD> 8.3) carried the other important QTL for heading date in 2004. In general, based on expression of stable and major effect QTLs in present study, it is possible to increase efficiency of marker assisted selection for the traits in breeding programs.

There is a high degree (>95%) of intraspecies similarity in the coat protein (CP) amino acid sequences within Passionfruit woodiness virus (PWV) and Cucumber mosaic virus (CMV), both infecting passionfruit vine in New South Wales. On this basis, a dual transgene containing the translatable cDNAs coding for the CPs of PWV and CMV was constructed in the binary vector pBI121 and used for transformation of Nicotiana benthamiana, a susceptible host to both viruses. The transformation was achieved by co-cultivation of the agrobacteria with the leaf disks prepared from the surface- sterilized leaves. Five transgenic lines including 1-1, 1-5, 1-7, 1-12 and 1-24 were regenerated. Insertion and transcription of the dual construct were confirmed, however, only the CMV CP was feasibly detectable by DAS-ELISA in the lines. Low level accumulation of CMV and/or PWV was evident in the lines. In the initail challenge trial where 1:10 dilution of plant sap was used, a 5-day delay in symptom was generally shown. Inoculations with 1:100 plant sap also gave similar results as with 1:10 dilution. Lines 1-5 and 1-12, which were inoculated with 1:1000 dilution of sap, remained uninfected by CMV till 27 dpi, whereas with PWV, 1-12 became infected by 11 dpi. Four cuttings of line 1-12 reacted diffferently to the challenge inoculations i.e. three of them resisted PWV, whereas two of them were susceptible to CMV. Since PWV CP was not detectable in the transgenic lines but evidence of resistance to PWV was found in them, this was suggestive of an RNA silencing mechnaism involved in the resistance. Because the CMV CP was detectable in the transgenic lines, this suggested requirement for the CP expression in the resistance. The resistance, or apparent immunity, was manifested by an apparent delay in symptom expression and accumulation of relatively low levels of the viruses.

During 2003-2004, a number of rhizospheric soil samples were collected of either healthy or symptomatic field grown melon plants infected with Fusarium oxysporum f. sp. melonis race1/2 (Fom). Twenty one bacterial strains capable of inhibiting Fom including Burkholderia sp., Bacillus sp., Streptomyces sp. and Pseudomonas fluorescens were isolated. The strains colonized roots of “long melon” cultivar of Mashhad and, within two weeks, resulted in increased fresh and dry weight, length of stem and root, and number and area of leaves, in the absence and presence of Fom, under greenhouse and growth chamber conditions. The growth inhibition of Fom in vitro was due to antagonism, siderophore and antibiotic production, and secretion of exogenous compounds. All antagonistic strains reduced infection of long melon seeds with Fom under controlled conditions.

Date bunch fading (DBF) is a serious disease of date palm (Phoenix dactelifera L.) in Iran. Fusarium proliferatum was isolated from the xylem of fruit bunch samples sent from Kerman and Fars provinces groves to the laboratory. Koch’s postulates were completed in the greenhouse by crown injection and root inoculations. Shriveling of the fruits was induced by peduncle inoculations. Symptoms on the seedlings indicated the effects of ethylene. The possible involvement of F. prolifertum phytotoxin(s) in the induction of DBF through elicitation of ethylene is discussed. The gas is suggested to be responsible for the gums deposits and, in turn, water stress resulted in shriveling and fading of the fruits.

Alfalfa crops were surveyed for the incidence of alfalfa mosaic virus (AMV), cucumber mosaic virus (CMV), peanut stunt virus (PSV), bean leaf roll virus (BLRV), bean yellow mosaic virus (BYMV) and bean common mosaic virus (BCMV) in the major growing areas in the southeast and central regions of Iran. Samples were collected between May 2009 and March 2011 and analyzed for viral infection initially by enzyme-linked immunosorbent assay (ELISA) followed by RT-PCR using capsid protein gene specific primers. In total, 634 symptomatic leaf samples were collected in four southeastern and central provinces of Iran representing 20 regions. Our results revealed a high incidence of AMV over a wide geographical area. AMV and BLRV were identified in most regions, whereas BYMV was found only in Yazd Province. PSV was detected in three regions, but not in Sistan- Balouchestan and Hormozgan Provinces. The highest incidence of viral infection amongst the surveyed provinces was recorded in Kerman (66.8%), followed by Yazd (39%), Sistan and Balouchestan (20.8 %), and Hormozgan (4.5%). AMV, BLRV, PSV and BYMV were present in 23.3%, 12%, 0.70% and 0.28% of the samples, respectively. CMV and BCMV were not detected in any surveyed region. Multiple virus infections were recorded in 42 samples. This is the first report on the detected occurrence of BLRV, PSV and BYMV in alfalfa in the southeast and central regions of Iran.

Viral symptoms indicative of Iris yellow spot virus (IYSV) were observed on onion in several fields near Chenaran in Khorasan Razavi Province. Mechanical inoculation of herbaceous hosts with onion sap extracts from symptomatic plants showed similar symptoms to those described for IYSV. The mechanically transmitted virus reacted only with antisera specific to IYSV in DAS-ELISA but not with antisera specific to seven other tospoviruses. In RT-PCR, a DNA fragment approximately 822 bp in size was amplified from infected Nicotiana benthamiana by using primers specific to the nucleocapsid (N) gene of IYSV. After cloning and sequencing, the deduced N protein sequence of two isolates (GenBank accession no. HQ148173 and HQ148174) showed 98% amino acid identity with a Sri Lankan isolate, 96% with a Dutch isolate and 92% with a Brazilian isolate. To our knowledge, this is the first molecular characterization of IYSV in Iran.

In recent years, changes in catchments water balance due to land use management have become the main concern of water resources authorities in Iran. Due to rapid population growth and land use changes, especially construction of Taleghan dam, Taleghan catchment has undergone rapid changes such as urban development, declining of rangelands, and deterioration of environment and erosion of soil resources by cultivating the hilly lands along the slopes for wheat or barely production. The extent of rangeland area shrinkage is substantial: from 83% during the early stages of dam construction down to 35% by the end of the study period. The ‘good’ rangeland area decreased to 5.90% from 34.49% while the poor rangeland increased from 19.04 to 23.35% during the period of 1987 to 2007. These changes could potentially have devastating impacts on water balance of the catchment. The main objective of this research was to examine the effects of land use changes on water balance of the Taleghan catchment before and after the dam construction. The Soil and Water Assessment Tools (SWAT) model was applied for predicting water balance in the middle and outlet of the catchment. The main input data for simulation of SWAT are Digital Elevation Model (DEM), soil type, soil properties, and hydro-climatological data. Comparing the water balance for 1987''s land use for the middle station (Joestan) and the outlet station (Galinak) showed that surface runoff was 21% of the precipitation for the upper part of the catchment and 33% at the outlet. Total groundwater and lateral flows were 37 and 19%, respectively. The water balance at the outlet was predicted for two other scenarios of 2001 and 2007. The results showed 7.3% increase in surface runoff and 11.3 and 11% decrease in the lateral flow and groundwater flow, respectively. These results indicated progressive increase in surface runoff and decline in interflow and groundwater flow.Therefore, one of the main challenges facing development planners is the control of the accelerated degradation of the natural resources that has been taking place during the last decade.

The prevalent method of irrigation in paddy fields in Iran is continuous ponding, which changes to intermittent method at the time of water shortage. Soil cracks are the main problem in intermittent irrigation. In this study, effects of adding rice straw on some soil physical characteristics and cracks were studied in paddy soils of the Guilan Province of Iran. The experiment was performed as split-split plots based on a complete randomized blocks design. Treatments included four soil textures (silty clay, silty clay loam, clay loam, and sandy loam), seven rates of rice straw (0, 2, 3, 4, 5, 6 and 7% by weight), and three soil moisture stages of drying conditions [primary stage (T1), initial crack stage (T2), final crack stage (T3)]. Results revealed that soil texture, rice straw rate, crack treatments, and their interactions had significant (P< 0.01) effects on soil moisture content, bulk density, and time to crack formation. During the drying stage (from T1 to T3), moisture content decreased, however, bulk density and time to crack formation increased. In silty clay soil, addition of 2-3% rice straw expedited crack formation, and an addition of 4-7% straw delayed crack formation. In silty clay loam soil, addition of 3-5% straw enhanced crack formation, and addition of 6-7% delayed crack formation. The addition of rice straw in clay loam and sandy loam delayed crack formation. In general, addition of rice straw increased soil moisture content, decreased bulk density, and delayed crack formation.

Simultaneous Heat and Water Model (SHAW) is based on the assimilation rate of melting and/or freezing of the accumulated snow as well as melting of ice in soil. The main objective of this study was to evaluate applicability of SHAW Model in determining maximum depth of frost penetration in soils in some typical climates of Iran. To this end, the daily data of air temperature, soil temperatures at different depths, duration of bright sunshine, and air humidity were collected for the period of 1992-2003 for four meteorological stations of Iran including Shahr-e- Kord, Urumia, Sanandaj, and Yazd. Then, the maximum soil frost penetration depth (SFPD) for each year in the above mentioned stations was determined based on both the measured temperatures at different layers of soil and the calculated values using SHAW Model. Results of the analyses indicated that there was a significant linear relationship between the observed and the calculated values of maximum SFPD. The obtained coefficients of linear correlation between the observed and the calculated values for meteorological stations of Shahr-e-Kord, Urumia, Sanandaj and Yazd were 0.90, 0.77, 0.84 and 0.94, respectively, all being significant at one percent level. According to the results, it was concluded that, with the yearly records of weather parameters and soil conditions, a reliable estimate of the maximum annual depth of soil frost penetration can be made in similar regions of Iran by application of SHAW Model.