JWSS - Journal of Water and Soil Science

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Downslope soil movement along riverbanks is a significant erosion process. Plant roots, particularly of woody vegetation, apparently stabilize soil on slopes because in most areas where the vegetation is removed, frequent bank failure occurs. Plant roots increase soil-shearing resistance both directly by mechanical reinforcement and indirectly through removal of pore water by transpiration. In this study, the effects of two plant species on the stability of the Karoon River has been investigated. To determine the In-situ shear strength of soil, a special device was designed and manufactured. This device is capable of measuring the shear strength of soil blocks as large as two cubic meters. In this study, twelve soil blocks, four blocks with roots of each tree and four blocks of root permitted were measured. Comparison of the soil shear strength with roots and root permitted soil shows that tree roots can significantly increase the shear strength of the soil. The amount of increase depends on the type of plant, the age of plant, the diameter of the roots and the percentage of roots in the block. In this study, the amount of increase varied between 20-66%. From the analysis of the data, two equations were developed to determine the increased shear strength.

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To improve livestock production and to modernize dairy husbandry in Iran, it is essential to disseminate the most recent information on dairy husbandry technologies and management practices through various means among farmers. An understanding of farmers’ communication behaviour is essential in formulating effective communication strategies for livestock development. For the purposes of this study, East Azarbaijan Province was selected. The study will examine how farmers obtain information on dairy husbandry technologies and management practices and how they communicate with agents of technology transfer (extensionists). The major channels and sources used in obtaining information and inter-system communication by farmers are discussed. To study the farmers’ communication behaviour, a sample of 154 farmers from a total of eight villages (four villages from high level plain areas and four villages from low level plain areas) were selected using “Stratified two-stage random sampling” method. Data were gathered by filling out questionnaires that had been tested before. The criteria like frequencies in terms of number and percentage, mean and product moment correlation were calculated. In addition, multiple regression analysis was used for the analysis of the data. According to the findings of this study, most farmers in the two groups (98%) had low information input score. The independent variables such as information output, farmer inter-system communication, farmer-researcher communication, farmer-extensionist communication, education, family education status and availability of input facilities had positive and highly significant relationships (P<0.01) with information input.

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This study utilized a descriptive-correlational surveying approach to examine some economic factors involved in the adoption of an integrated campaign to control rice stem borer (Chilo suppressalis) in Isfahan Province. The population consisted of farmers living in the vilages where Biological Control Plan was conducted (N=6000). The population frame was obtained from Isfahan Agricultural Organization. The sample was obtained using the cluster random sampling method (n=361). Questionnaire and interview were used for data collection in this study. Face and content validity of the instrument was established using a panel of experts consisting of senior faculty members in agricultural extension and education at Tarbiat Modaress University. Further, the agricultural officer of Isfahan Province validated the questionnaire. A reliability analysis was conducted and Cronbach alpha value was reported to be 83 percent. The results showed that the rate of adoption of Integrated Campaign to Control Rice Stem Borer among the farmers was moderate. Among the economic characteristics, there was a significant relationship between adoption of integrated campaign and area of land, amount of area under cultivation, degree of family cooperation in the agricultural activities, access to agricultural inputs, access to financial resources, and yield of rice per hectare.

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‘Golden Delicious’ apples were vacuum infiltrated (250 mm Hg) with 0, 4, and 6% solutions of CaCl₂ followed by heat treatment for 0, 48 and 72 hours at 38^oC. Treated fruits were stored at 0^oC with RH of 85-90% for 2.5 and 5 months, followed by one week of storage at 20C. The results showed that fruits treated with 4 and 6% of CaCl₂ significantly increased calcium content of fruits after 2.5 and 5 months of storage at 0^oC. With increasing calcium content, fruit firmness also increased. There was a positive relationship between fruit firmness and calcium content and regression coefficients after 2.5 and 5 months of storage at 0^oC were 0.77 and 0.83, respectively. Heat treatment for 48 and 72 hours at 38^oC significantly increased fruit firmness. Calcium chloride at 4 and 6%, plus heat treatment, significantly increased fruit firmness of those fruits held for one week at 20^oC after removal from cold storage. In the second experiment, vacuum infiltrated fruits with 4 and 6% solutions of CaCl₂ plus potassium permanganate (0, 10, and 20 g/bag) had no significant effect on fruit firmness, but potassium permanganate alone significantly increased fruit firmness.

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The objective of this research was to evaluate bromide leaching in a field under corn, wheat and alfalfa. Potassium bromide (300 kg/ha) was uniformly applied and 15 mm of water was sprinkled over the plots in the first and second years. Plots were leached 8 times during the first year and 9 times in the second year (each time with 100 mm of water). Soil samples were collected at 0-30, 30-60, 60-90 and 90-120 cm depths two days after each leaching practice. Bromide concentration in soil samples was measured using an ion selective electrode. Moisture content in each plot was measured using a neutron meter to a depth of 120 cm and after calculation of evaporation from soil surface, the net water applied was determined. CXTFIT software and Regional Stochastic Model (RSM) were used to simulate leaching under field conditions. The results showed that flow velocity and dispersivity of treatmens were not significantly different from the control in the first year, indicating that treatments had no effect on preferential flow. Control treatments were not significantly different in the first and second years. In the second year, flow velocity in wheat, corn and alfalfa treatments were 1.54, 1.86 and 2.21 times higher than flow velocity in the control, respectively. Dispersivity in alfalfa and corn treatments were 4.30 and 5.30 times higher as compared to the control. The increase in flow velocity and dispersivity is caused by an increase of preferential flow in the second year. The root channels remaining in soil at the end of the first year may also have increased preferential flow. After adding 25 cm of water, 30% of bromide leached from the top 50 cm soil in all plots in the first year and control plots in the second year but the values in the second year were 47, 67 and 70% of bromide leaching from the top 50 cm soil in wheat, corn and alfalfa plots, respectively.

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Iron (Fe) availability is low in calcareous soils of Iran due to high pH levels and presence of excessive amounts of CaCO₃. Overfertilization by phosphorus (P) fertilizers may also decrease Fe availability. The objective of this study was to evaluate the effects of P, Fe and their interactions on the growth and chemical composition of soybean [Glycine max (L.) Merrill] 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 FeEDDHA) in a completely randomized design with four replications. Plants were grown for 8 weeks in a loamy soil, classified as Chitgar series (fine-loamy, carbonatic, thermic, Typic Calcixerepts). Results showed that P application up to 80 and Fe at 2.5 mg kg^-1 increased shoot dry matter. Phosphorus concentration, total uptake and P:Fe ratio in soybean increased by P application but decreased by Fe application. Application of Fe up to 2.5 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. Interaction of P and Fe had no effect on shoot dry matter. Zinc (Zn) and copper (Cu) concentrations decreased significantly when P was added and manganese (Mn) concentration increased up to 40 mg P kg^-1 but decreased at higher rates. Iron application had no effect on soybean Zn and Cu concentrations but decreased Mn concentration at all rates. Prior to any fertilizer recommendations, it is necessary to study the effects of P, Fe and their interactions on soybean under field conditions.

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Cultivating rangeland to be shifted to crop land farms commonly causes soil degradation and runoff generation. This study was conducted to evaluate the cultivation effects on runoff generation and soil quality. The experiment was performed in a rangeland and a 40-year cultivated land located at two slope positions (back slope and shoulder) of a hillside in Dorahan, Chaharmahal & Bakhtiari Province. A 60±5 mm.hr^-1 rainfall intensity was simulated by a rainulator. Organic matter, mean weighted diameter, saturated hydraulic conductivity, collected runoff and sediments were measured. The differences between the means were tested using T-test. Results showed 35, 53 and 8% increases in the organic matter, mean weighted diameter, and saturated hydraulic conductivity in back slope, respectively. The increases in these parameters in shoulder position were 39, 60 and 33%. The values for runoff and sediments in back slope were 3 and 8 times greater than in other similar positions while the values in the shoulder position were 11 and 55 times greater than the same values in other positions.

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In a completely randomized design (CRD) experiment with 6 treatments and 4 replicates per treatment, the effect of energy and protein dilution during 6-12 days of age was tested in broilers. Rice hull was used for dilution of energy and protein at levels of 0.05 (control), 10, 15, 20, 25 and 30 percent. The metabolizable energy and crude protein content of the experimental diets were 3089, 2780, 2626, 2472, 2317 and 2163 KCal/kg and 21.45, 19.29, 18.23, 17.16, 16.10 and 15.02 percent, respectively. The results indicated that diet dilution at early age (6-12 days) increased feed consumption but energy and protein intake and weight gain were reduced. No significant differences in body weight were observed due to compensatory growth among treatments. After feed restriction, feed intake was lower for the birds receiving diluted diets as compared to control. Meanwhile feed efficiency somewhat improved among the birds fed with diluted diets, but the differences were not significant. Diet dilution had no significant effect on carcass and abdominal fat percentage at the slaughter age (45 days). Diet dilution with rice hull at 20 and 25 percent decreased feed consumption and improved feed efficiency and, therefore, its use can reduce feed cost.

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The effect of adding two urea levels (0.5 and 0.75% on fresh basis) to whole-crop barley (WCB) on chemical compositon and digestibility in Ghezel rams was studied. The effect of including these silages in the ration of fattening Ghezel and Mehraban rams was also investigated. Urea supplementation of WCB silage resulted in an increase in pH, total nitrogen level, and ammonia-nitrogen concentrations (P<0.05). Apparent digestibility coefficients of dry matter, organic matter, acid detergent fiber, and neutral detergent fiber of WCB silage were not affected by urea treatment (P>0.05), but apparent digestibility coefficient of total nitrogen was higher for 0.5% urea-WCB silage. Apparent digestibility coefficients of total nitrogen and nitrogen balance were higher for 0.5% urea-WCB silage than for 0.75% urea-WCB silage, but the differences were not significant. Ruminal fluid pH at 2.5 h, and ammonia-nitrogen concentration at 4 h post-feeding were higher for 0.75% urea-WCB silage than for 0.5% urea-WCB silage (P<0.05). BUN levels (<20 mg per dl) in sheep fed with a mixture of alfalfa hay and silages were not affected by the treatment. The potential and effective degradabilities of dry matter and crude protein were higher for 0.75% urea-WCB silage. Feed performance and carcass characteristics were not significantly different amongst diets. The results showed that urea supplementation at 0.75% fresh basis, at the time of ensiling, may have a beneficial effect on feeding value of WCB silage.

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Citrus juice and concentrate are among the major industrial products in Iran. Large quantities of citrus peels with considerable amounts of pectin are also produced. Pectin could be extracted from the peels to be used as a gelling agent in some food products. Unfortunately, all pectin used in the food industry is imported. This study was carried out to find the best conditions of pectin extraction from orange peels. Samples of orange peels were collected from a concentrated orange juice factory. Pectin was extracted by sulfuric, nitric and hydrochloric acids. Certain qualitative and quantitative tests, such as yield of extraction and cost of extraction were determined. Also, food safety aspects as a result of using the above acids were considered. Hydrochloric acid was found to be the most suitable acid. In the second part of the research, the effects of temperature (85 and 90˚C), time (40, 50 and 60 minutes) and pH (1.6, 1.8 and 2.0) on the yield of extraction, purity, gelling ability, percentage of methoxylation and degree of esterification of the extracted pectins were measured. Statistical analysis of the results showed that the best conditions for the extraction of pectin include a pH level of 1.6, a temperature of 90˚C and a period of 50 minutes.

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A total of forty-three isolates of Ascochyta rabiei obtained from infected seeds and plants of chickpea from different areas of Kermanshah, Lorestan, Hamadan, Kordestan, and East and West Azarbaijan provinces were studied during the period 1996-1999. A rapid and simple method was developed for pathogenicity test in CDA (chickpea seed meal dextrose agar) medium. CDA medium was inoculated with different isolates and incubated at 21±1 ^oC for 9 days. The disease severity was scored as 0-100% at 24-hour intervals up to five days. Virulence forms were designated according to spectrum of disease reactions of each isolate. Thirteen isolates (IK04, IK08, IK10, IK13, IK14, IK17, IK19, IK21, IL01, IL10, IO00, IE04, IE06) were distinguished as highly virulent (HV) and 7 isolates (IK03, IK06, IK15, IE01, IE08, IL04, IL06) as weakly virulent (WV). Polygalacturonase activity of these isolates from 6 days old inoculated PZ (pectin zymogram) medium were assayed. Comparison of the results of pathogenicity test and PG activity of 43 isolates demonstrated that HV isolates show predominant enzyme activity while the WV isolates show enzyme activity.

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During the period from 1997 to 1998, samples of wheat leaves were collected from different wheat farms in Fars and Kohgiluyeh & Boyrahmad provinces to identify the causal agent of wheat leaf blight. On the basis of LOPAT tests and production of fluorescent pigment on KB medium, 181 bacterial isolates were recovered from the samples. Based on biochemical, physiological and pathogenicity tests, the isolates were categorized in five groups. One group was found to be Pseudomonas fluorescens (Pf) and the remaining groups were identified as P. syringae pv. syringae (Pss). The pathogenicity test indicated that Pss strains were the causal agent of bacterial wheat leaf blight in Fars and Kohgiluyeh & Boyrahmad provinces. Whole protein electrophoretic patterns were similar in Pss isolates but only a few showed small variation in some subordinated bands. Pathogenic strains of Pss were also isolated from annual and perennial weeds such as foxtail, hairy vetch, oat grass, barley grass and Cynodon dactylon in some areas including Saadat Shahr and Marvdasht. Among the wheat cultivars tested, Tajan was susceptible to the pathogen but others were immune, resistant, moderately resistant, or moderately susceptible. The results showed that Pss is a seed-born pathogen in wheat kernel perhaps as endophyte in the seeds.

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The biology of predatory fly, Leucopis glyphinivora Tanas. was studied under greenhouse conditions. Adult longevity was 8 days and the average fecundity was 35.7 eggs. Incubation period, the 1st, 2nd, 3rd larval instars and puparium duration averaged 2.7, 2.16, 3.48, 5.7 and 8.45 days, respectively. Each generation lasted about one month. The predator efficiency was studied by applying the egg together with the adults of A. fabae at ratios of 1:1, 1:2, 1:4, 1:8 and 1:16 on broad bean. First larval instar was exclusively feeding on small nymphs (1st and 2nd nymphal instars) of aphid. Predator:prey ratios of 1:4, 1:8 and 1:16 decreased the number of prey to 97.9%, 98.8% and 61%, respectively, but ratios of 1:1 and 1:2 were unsuccessful in decreasing the number of preys due to predatory larvae leaving the host plant for searching small nymphs of aphid. As a result, the predatory larvae were efficient merely in a particular range of aphid density and age structure.

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To determine the effects of spawning frequency and density of incubating eggs on the survival rates of eggs and larvae in rainbow trout, five different groups of broodstocks with varying spawning frequencies were stripped. After fertilization, the percentage of survival at different stages of development, from eying, hatching to free swimming fry stages and also growth rates of larvae were determined. Moreover, the effects of incubating egg density (4000, 7000, 10000 per tray) on the different developmental stages of egg through free swimming larvae for each group of broodstock was studied. The study was carried out in a completely randomized design as a 5*5*3 factorial arrangement with three replicates. The results indicated that survival and growth rates are significantly correlated with spawning frequency (P<0.05) so that, survival and growth rates from fertilization to free swimming fry in broodstocks at their third and fourth spawning period were significantly different from the results obtained for broods in the first, second and fifth or higher spawning periods (P<0.05). Although the holding densities had no significant effects on the growth rate of larvae from different broodstocks, the survival rates from fertilization to free swimming stage was affected by incubating density so that the significantly lower value was recorded for density of 4000 per tray (P<0.05). In general, the results indicate that eggs obtained from broodstocks at their third and fourth spawning years have a better performance than those obtained from younger and older spawners. Also, the low holding density of eggs could decrease the performance of the fertilized eggs during incubating period.

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Fecundity of Shah-Koolee in the Sefidrood river, which is one of the economic and popular fishes in northern part of Iran, was studied. From April to August 2000, 539 Shah-Koolee fishes were caught at the specific station in the Sefidrood river from the sea shore to Kisum. Seventy one samples of unspawned fishes were taken, the primary biometry was performed, specimens of the different parts of the ovary were prepared and absolute fecundity was determined through gravimetry. Maximum and minimum fecundity rates were 18860 and 2929 eggs, respectively, that related to eight- and three- years old fishes. Relative fecundity was 132±37 and 72 eggs per gram of weight. The relationship between absolute fecundity and length and weight was linear, correlation and numerical quantities of a, b and r were calculated and regression graph was drawn. Gonado Somatic Index (G.S.I.) was used to determine the natural spawning region and calssification was done on the basis of two factors, age and station. It was found that three- years old fishes with a regeneration power of 17.05 in comparison with other age groups had higher potential. This index also showed that Astaneh and Kisum stations were favorable places for natural spawning of these fishes.

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Antagonistic fungi Trichoderma harzianum (T₁, from bean fields in Ahwaz, T₂, from rice fields in Rasht), T. viride (T₃ from bean fields in Shahriar, T₄ from the collection in Plant Pest and Disease Institute, Tehran), Gliocladium virens (from bean fields in Kamal Abad, Karaj) and some fungicides (Benomyl, Carbendazim, Carboxin-Thiram, edifenphos and Zineb) were used to control sheath blight of rice incited by Rhizoctonia solani in vitro and under greenhouse conditions. The experiment was carried out in a completely randomized design with 12 treatments and four replications on Khazar rice cultivar in a soil infected by R. solani under greenhouse conditions. The results showed that the antagonistic fungi reduce sheath blight by 19.8 (T₁), 21.5 (T₂), 27.5 (T₃), 19.6 (T₄) and 18.5 (G₁) percent. The antagonistic fungi in order of efficacy were T₂>T₃>T₁>T₄>G₁. Benomyl, Carbendazim, Carboxin-thiram, Edifenphos and Zineb reduced disease by 32.5, 21.5, 12.8, 9.5 and 0 percent, respectively. Statistical analysis of data indicated that there existed no significant differences between T₁, T₃, T₄, and G₁ and Carbendazim fungicide to control disease however, the isolate T₂ was as effective as Benomyl but Zineb had no effect on sheath blight.

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Rice is only second to wheat as a major food for Iranians. It has to be dried for processing and/or storing due to excessive moisture content after harvesting. In most parts of Iran, rice is sun-dried by spreading it on the ground under solar radiation which leads to excessive losses such as attacking birds and rodents, grain contamination, wind and rainfall hazards, as well as thermal and moisture stresses. The present research aims to investigate the feasibility of thin layer solar drying process of rough rice to determine the appropriate bed depth of seed. A mixed mode passive solar dryer was used. In this system, hot air is provided by natural convection through an air solar collector. Thin-layer drying process was investigated using the thin layer mathematical models (Newton and Page models). One of the main aims of this research was to find an appropriate depth that can be regarded as thin layer. Therefore, bed grain depths of 2, 4 and 6 cm were selected for the experiments. The results illustrated that the bed depth of 2 cm showed the thin layer drying behavior whereas bed depths of 4 and 6 cm did not.

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Pistachio oyster shell scale is one of the important pests of pistachio in Iran whose females are reported to exist in two or three forms, each form developing on a specific part of the pistachio tree. In this study, abundance of the pest is investigated on leaves and branches for different ages, two heights and four cardinal directions of tree crown. Paralelly seasonal population fluctuations of three forms were studied on leaves, and one-and two-year-old branches separately. This insect overwintered as female mostly on one and two-year-old branches. It had two separable periods of activity, through the season. In the first period, eggs mostly hatched in April and crawlers mostly settled on leaves, fruits and newly grown twigs but rarely on older branches.These populations are male and female. In the second period, eggs mostly hatched in June, and crawlers settled mostly on leaves and one and two-year-old branches, but all individuals settled on leaves are males and those on branches are females. Population density is significantly higher on upper surface of leaves than on the lower surface. Analysis of variance showed that only significant differences existed in densities observed between trees in both generations, and also between two heights of tree crown for populations settled on wood. Two predatory species from Cybocephalidae and Coccinellidae, one ectoparasitoid from Aphelinidae and two endoparasitoids from Encyrtidae were collected as natural enemies of this pest in Isfahan.

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In this study, susceptibility of the first three larval stages of Spodoptera exigua to Bacillus thuringiensis was investigated. To determine the LC₅₀ values for each larval instar, 6 different logarithmic concentrations of Bacillus thuringiensis were used. A control was also included in each of the bioassays. The value of LC₅₀ for 1st instar larvae, that had been treated one to four hours after hatching, was 311.617 ppm. For the 2^nd and third instars, the larvae values of LC₅₀ were 1356.95 and 2708.27 ppm, respectively. It was clear that larval susceptibility to Bacillus thuringiensis decreased with age. In order to enhance the Bacillus thuringiensis efficiency to control Spodoptera exigua under field conditions, Bacillus thuringiensis should be applied at egg hatch peaks.

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Numerous methods are used in the investigation of floods in catchments such as regional flood frequency analysis. Regional flood frequency analysis relies on physical, climatic and ecological characteristics of catchments and applies statistical methods to study flow records. Hosking and Wallis developed Probability Weighted Moments and presented L-moments statistics as a new tool for flood frequency analysis. In this paper, the theory of L-moments was used to study the flood frequency of central catchments of Iran. A number of 27 sites each with more than 5 years of observed data were studied. In the first step, the diagram of L-kurtosis versus L-skewness was used and proper distributions for each site were applied. In order to eliminate the heterogeneous sites, homogeneous tests based on D, H₁, H₂ and H₃ criteria were performed indicating that two sites appeared to be heterogenous. Next, using Goodness of Fit Test, the best regional distributions were determined which are GL, GEV, GN, PE3 and GPA, respectively. Finally, quantile estimates for distributions accepted at a 90% level were presented.