JWSS - Journal of Water and Soil Science

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Agricultural colleges have three main objectives: training, research, and offering public services. Transfer and dissemination of agricultural knowledge and technology is the best example of universities’ services. In this regard, agricultural extension has the important role of linking agricultural colleges with agricultural industry. The linkage between extension and agricultural colleges is effective in promoting the two organizations and ultimately enhancing the development of agriculture. Therefore, the significance of this linkage has been emphasized by many program planners as well as researchers.

This descriptive research was conducted to analyze the perception of the faculty members at Agricultural College of Shiraz University and the extension agents and specialists of Fars Province. A theoretical framework was developed based on a “communication model”, and forty-seven factors effective in establishing and promoting the linkage between research and extension were recognized. The results revealed that the most important factor in research-extension linkage is “the degree of contact and knowledge of local agricultural affairs by researchers”. The paper concludes by providing recommendations that could be used to strengthen the interaction between research and extension institutions.

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Quantity-intensity (Q/I) curves and their derived parameters provide general information about soil K availability. This investigation was conducted to obtain Q/I parameters and to study the relationships between the Potassium Q/I parameters and the properties of 15 soils from central and northern Iran. Soil samples were equilibrated with solutions containing different potassium activity ratios (AR^k). Changes in potassium concentrations in the equilibrium solution (ΔK) were plotted against activity ratio of K, and Q/I parameters were determined. Correlations between Q/I Parameters and some properties of soils were studied.

The Q/I plots showed the common shapes described in the literature whereas high variations were observed in the soils with respect to AR°, ΔR°, BPC^k and K_x. The potassium activity ratio at equilibrium ranged from 0.005 to 0.532 with an average of 0.02 (mmol L^-1)^0.5. The potassium potential buffering capacity (PBCk) ranged from 4.40 to 76.3 with an average of 16.2 (mmol kg-1) / (mmol L-1)0.5. The readily exchangeable potassium (ΔK°) ranged from 0.007 to 0.737 with an average of 0.25 cmol kg^-1 and slowly exchangeable potassium (K^x) ranged from 0.023 to 0.55 with an average of 0.3 cmol kg^-1. Highly significant linear correlations were found (α=0.01) between PBC^k and CEC (r=0.66), AR° and exchangeable potassium percentage (r=0.76), AR° and solution potassium (r=0.89), and between ΔK° and exchangeable potassium (r=0.79). Because of high variations in physicochemical properties of soils, correlation coefficients between Q/I parameters and soil properties were not very high.

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A study was conducted to determine irrigation scheduling of pinto bean and to evaluate the effect of its planting date. A split-plot with complete randomized block design with four replications was used at Isfahan University of Technology Research Station in Shervedan-Falavarjan, The main plots were three irrigation regimes of T1 to T3 (irrigation after 50±3, 70±3 and 90±3 mm evaporation from class A pan, respectively) and the sub-plots were two planting dates of May 28 and June 28.

The results showed that delayed planting from May to June caused earlier flowering, physiological maturity and reduction of 29.6% in grain yield. Grain yield in T1 to T3 treatments were 3585.1, 3510.5 and 1925.8 kg/ha, respectively. The difference between grain yields of T1 and T2 with T3 treatments were significant at 1% probability level. Biological yields at May 28 and June 28 planting dates were 8257.1 and 5535 kg/ha, respectively, which were significantly different. There was no significant difference between biological yields of T1 and T2 treatments. Number of pods per square meter was the most important component of grain yield and 85% of grain yield difference was due to this part. Harvest index was affected by irrigation treatment and planting date. Mean harvest indices for T1 to T3 treatments were 45.5, 46.1 and 37%, respectively, and 42.8% and 44.9% for the two planting dates. Water use efficiencies for grain yield in T1 to T3 treatments were 0.557, 0.556 and 0.329 kg/m3, respectively. Generally, treatment T2 was shown to be the best irrigation regime.

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Data of 1200 male and female chicks from 90 sires were used to estimate the heritabilities as well as genetic and phenotypic correlations of body measurements and carcass characteristics in three genetic groups, namely, crosses of native chickens with an exotic breed (group A), native chickens which were selected for two generations on the basis of 8th week body weight (group B) and a native control group (group C).

The effects of genetic group, sex and system (litter vs. cage) on body measurements (shank and breast traits) and carcass characteristics were studied. Data of body measurements were collected at 6th week of age, and carcass traits were recorded at slaughter time at 10th week of age (except breast angle which was recorded at 8th week).

All carcass traits and body measurements except shank were significantly affected by genetic groups (P<0.05). Sex and system of rearing did not have any significant effect on body measurements and carcass traits. Estimated heritabilities for body measurements and carcass traits showed a wide range. Breast and shank measurements had the lowest and those related to abdominal fat had the highest heritabilities. Phenotypic correlations for all of the body measurements were lower than genetic correlations among these traits. Genetic correlations between body measurements and carcass characteristics were mostly significant

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An experiment with 720 pullets was conducted to investigate the effect of dietary energy levels of pullet and dietary energy and fat of laying ration on subsequent performance parameters during 14-20 and 22-44 weeks of age. In the first period, white leghorn pullets were fed with two diets of low and high density energy (2600 and 3200 Kcal ME/kg). In the lating period (second period), birds, in each treatment of pullet period, were fed with six diets containing three levels of low, medium and high energy (2600, 2750 and 2900 kcal/kg) at two levels of supplemental fat (zero and 2%). All diets were formulated to meet minimum NRC (1994) requirements of amino acids and protein. This experiment was done in randomized complete block designs with 5 replicates. The levels of energy in the growing period did not affect egg production, egg weight, daily feed intake, feed conversion rate and age of pubertal maturity in laying period, but pullets fed with high energy diet had significantly higher weights as compared to low energy diet in the beginning of laying period. In the laying period, the use of supplemental fat (2%) improved egg production and egg weight, but feed intake and feed conversion rate were not affected. Means of feed conversion rate, feed intake and egg production during laying period in low energy diet were greater than those as compared to high energy diet, but egg weight was not affected by energy level of diets. Low energy intake to protein intake ratio in low energy diet versus high energy diet may be a reason for greater egg production in lower energy than in higher energy diets.

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This experiment was carried out to study the effect of ionophore drugs (Salinomycin, Lasalocid and their combination) on the performance of broiler chicks. Also their relationship with methionine (three levels) was 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 and three levels (0/0, recommended and 1.5 times recommended) of drugs and three levels (0.0, 1% and 0.2%) of supplemental methionine.

The results indicated that these drugs reduced body weight gain significantly (p<0.05) at 21 and 56 days of the experiment. Decreasing feed consumption and increasing feed conversion was significant (p<0.05) due to Lasalocid supplementation. Increasing drug level significantly (p<0.05) reduced body weight gain and feed intake and feed conversion was increased at 21 to 42 and 0 to 56 days of the experiment. The effect of supplemental methionine on body weight of 42 days (P<0.05) and feed conversion at 21 to 42 and 0 to 56 days (p<0.01) were significant. The interactions between drug type and drug level on body weight gain, feed consumption and feed conversion were significant (p<0.05). Lasalocid significantly (p<0.05) increased water intake. Drugs did not affect litter moisture and mortality. The results showed that Salinomycin was better than Lasalocid. Also supplemental methionine was not effective in compensating for the growth depression caused by ionophore drugs.

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In this study 2510 records of reproductive traits from the mating of 879 ewes with 164 rams of Bakhtiari sheep breed, during 1989 to 1997, were used in order to estimate the effects of environmental factors on their reproductive performance.

The mean and standard errors of reproductive traits were as follows: conception rate, 0.9±0.01 number of lambs born per ewe exposed, 1.06±0.01 number of lambs born alive per ewe exposed, 1.01 ±0.0l, number of lambs weaned per ewe exposed, 0.93±0.01 litter size alive at birth, 1.10±0.01 litter size at weaning, 1.01±0.02 and number of lambs weaned per lambing ewe, 1.09±0.01. The effect of joining year was highly significant (P, 0.01) for all of the considered reproductive traits. Age of ewe at joining time was also a significant (P<0.05 and 0.01) source of variation for most of the reproductive traits. Maximum reproductive performance occurred for ewes of 4 to 5 years of age. Mating time was also a significant factor (P<0.05 and 0.01) for all of the reproductive traits. Maximum reproductive performance occurred for ewes mated during the first half of the mating season. Type of birth was a highly significant factor (P<0.0l) for the number of lambs alive and weaning traits. However, due to significant effects of environmental factors on considered traits, and in order to increase reproductive efficiency, one should improve environmental conditions (barn, management, feeding system and ... ) as well as organizing mating plan for the first half of the mating season and make a suitable age combination of ewe herd. In this combination, decreasing the percentage of ewes older than five years could benefit herd performance.

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In order to estimate the heritability of morphological characters of worker honey bee and honey yield, 30 queen-mothers were selected randomly from the apiary of Research Center of Animal Science and Natural Resources in Isfahan Province. From each queen-mother, five queen-daughters were reared and introduced to equalize colonies after natural mating of queens. Summer honey yield was measured, while fall honey production was calculated from area of sealed honey combs. The total honey was calculated by adding summer honey production to fall honey production. Morphological characters were measured under a stereo-dissecting microscope fitted with a calibrated micrometer reticle according to Ruttners method (1985).

 Heritabilities were estimated by intraclass correlation method. Heritabilities of summer, fall and total yearly honey yields were estimated to be 0.64, 0.51 and 0.30, respectively. Estimates of heritability of morphological characters for probscis length, tibia length, femur length, metatarsus length, metatarsus width, forewing length, forewing width, cubital index, hindwing length and number of hamuli were 0.64±0.08, 0.45±0.07, 0.50±0.07, 0.47±0.07, 0.33±0.06, 0.42±0.06, 0.89±0.10, 0.5±0.07, 0.94±0.10 and 0.45±0.07, respectively. It could be concluded that in order to increase honey yield in either season (summer or fall), selection must be based on the amount of honey yield in the corresponding season. Thus, heritabilities of forewing and hindwing lengths were high selection according to these morphological characters would, therefore, change the size of these characters.

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Four hundred isolates of Ascochyta rabiei (Pass.) Lab. collected from different parts of the country, such as Zarivar Marivan Lake in Kordestan Province Shabestar and Khosroshahr in Eastern Azarbaigan Province Serow, Bokan and Shahindeg in Western Azarbaigan Province Mashhad and Ilam were used in this experiment.

These isolates showed little differences in their cultural and morphological characters and pathogenic behaviors. They were categorized into 17 groups on the basis of collection regions and, based on cultural characteristics, were then reduced to 11 groups. Isolate number 16 from Mashhad showed the highest growth rate while isolate number 1 from Kordestan had the lowest growth rate.

One isolate was chosen as a representative for each group. Pathogenicity of representative isolates from each of the 11 groups were tested. Reaction type of all isolates was studied on differential hosts and one local chickpea line Jam was examined, using Reddy and Nene (1979) method. Races No. 4 and 6 were identified as the two physiologic races.

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In 1996 and 1997 pistachio orchards in Isfahan Province were surveyed to determine the presence and damage levels by Eurytoma plotnikovi Nikolskaya and Megastigmus pistacia Walker. In order to investigate seasonal population fluctuation of E. plotnikovi, larval, pupal and adult stages were monitored in three orchards. In each orchard, 200 nuts with more than 50% infestation to overwintering larvae were dissected and examined twice weekly. In 1997 in one orchard, at intervals of one week, 100 randomly selected fresh nuts were examined to determine oviposition trend and damage development. In this field, the biology of the pest was also compared to developmental stages of pistachio trees. In most orchards visited, E. plonikovi was present and was the dominant species in relation to M. pistacia and its damage varied between 0.8-75%. In 1997, start, peak, and end of pupal stage were observed on April 4th, May 7th and May 21st. Start, peak and end of adult emergence occurred on May 4th, May 18th and June 4th. In two other orchards, almost a similar trend was observed. Start, peak and end of oviposition were also observed on May 18th, May 28th and July 2nd. Development of pistachio tree was divided into nine stages and the above mentioned dates were compared to that.

E. plotnikovi had one generation every one or two years. Only one egg was found in each infested fruit and first stage larvae had a long prefeeding period. The use of the information obtained from this study in the management of these pests is discussed.

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Peak discharge is one of the basic parameters in the design of hydraulic structures. There are various methods for peak discharge determination. Regional flood frequency analysis is based on physical, climatological and hydrological characteristics of basins. The objective of this study is to examine different models for the estimation of quantiles for some catchments in western Iran (namely: Gharehsoo, Gamasiab, Kashkan, Seimareh, Sezar and Abshineh) for which only maximum daily mean discharge data exist. In this research, peak and maximum daily mean discharges for 11 stream gauging stations were collected for a 21-year period. The ratio of these two discharges (R) and mean and standard deviations of peak discharges and maximum daily mean discharges were computed. Catchment characteristics including catchment area, catchment perimeter, main channel length, mean elevation, mean slope equivalent rectangle length, circular ratio, Gravelius coefficient, drainage density, time of concentration, relief ratio and diameter of the circle having equal area with the catchment were computed. Linear regression analysis was performed between independent variables of the catchments and mean standard deviation of the parameter “R” to develop a relation. The results of this study can be applied to the estimation of extreme flow values for non-recording stream gauging stations (daily reading sites).

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In this study, seven citrus gardens in different parts of Darab were chosen to evaluate the drip irrigation systems. The evaluation process was based on the Merriam and Keller’s model (1978). Besides the evaluation of drip irrigation systems, the water requirement of citrus was estimated using four models including Blany-Criddle modified by FAO, Hargrive-Samani, Pan Evaporation and Solomon-Kodama model. On the basis of the results obtained by Hargrive-Samani with 1296 mm annual water requirements, a comparison was made between irrigation with existing systems and irrigation under favorable and desired conditions.

The results from field measurements indicate a considerable reduction in the emitter discharges. The low pressure and emitter clogging could be two major reasons for the problem. Low pressure at head control, topography, head losses and also using no filter(s) or unefficient filters are the main reasons for the reduction. In some gardens, overirrigation even up to 2.5 times of water requirement was practiced by using extra emitters and increased irrigation times. Overirrigation causes considerable water losses through deep percolation and in reased overwetting area.

Field measurements indicated a good emission uniformity (EU) for the fields with overirrigation. EU in chosen fields varied from 40 to 91%, AELQ varied from 31 to 82% (poor to good) and PELQ varied from 36 to 82%. This study showed that most farmers are not familiar with plant water requirements. The fields with efficient filtration due to using extra emitters per plant are mainly overirrigated. But fields without any filter of unefficient filters are not irrigated sufficiently. The very high manufacturing variation coefficient of IEM emitters (C_v=0.22), which are widely used in Darab, causes a design emission uniformity of 55%.

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The application of “Modified Einstein Procedure” is recommended by the Specialized Committee on Sediment, Iranian Ministry of Energy. However, this method has not been applied to any river in the country. It is the purpose of this study to investigate the total sediment load of the Karun and Karkheh rivers at Ahwas and Hamidieh stations.

The graphical calculations of the method are very complicated and time consuming. Therefore, a mathematical model has been developed in this study to improve the accuracy, simplicity and speed of computations. The required data were obtained from the above stations for seven years (1988-95), and applying these data, the total sediment load was calculated using the model. The bed load for the above stations was also computed and the ratio of bed load to total sediment load was calculated. In addition, measured data from East Fork river (in USA) were applied to examine the accuracy of the method in estimating the bed load. Comparison of the measured and computed results shows that the “Modified Einstein Procedure” estimates the amount of bed load with a high accuracy. The relationship between the bed load and suspended load and also between the total load and the stream discharge have also been established.

Finally, it is concluded that the “Modified Einstein Procedure” with minor modifications can be successfully applied for the above-mentioned rivers of Karun and Karkheh.

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Mutual understanding among officials and followers has been a point of concern in behavioral management. Natural resources extension which, from the very first step, is concerned with the exploration of practical problems is in serious need of an atmosphere of mutual understanding between agents and clientele. In this research, attention was drawn toward the measurement of mutual understanding between executives and nomads regarding nomads’ problems in utilizing natural resources and breeding cattle in Isfahan Province. For this purpose, initially, understanding between nomads and natural resources administrators (extension agents and specialists) regarding their respective problems were measured and compared. The research population of the study consisted of two groups. The first, involved 32 administrators, extension agents and specialists, and the second, 75 nomad families. Two different questionnaires were developed for the study as research instruments in which 52 items regarding nomad problems were included. Each part of the population was asked to rank the items accordingly. Then, some nonparametric tests such as Kruscall Wallis and Mann Whitny U tests were applied to compare the mean rank for each item within and between the two groups.

Results showed that the administrators and nomads had different attitudes in only two of the 52 items. Administrators had no statistically significant different attitude in 52 problems. Eliminating the discriminating items, the attitudes in only two groups were compared and results showed that they had no significant difference in the remaining 48 items. Therefore, extension agents can follow these problems based on their mean rank priority in their developmental projects. This method of data reduction and understanding field constraints can be applied to the studies dealing with planning agricultural and/or natural resources development projects through extension education.

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Marine products are currently important in Iran due to the following reasons: 1) aquatics are recognized as safe and healthy food by food scientists 2) because of low dependence of fishing technology on foreign resources, they are more reliable sources for protein and food security. Therefore, it is important to increase labor productivity using advanced fishing technology under a sustainable fishery management policy. In general, the prevailing methods of fishing in the southern coasts of Iran can be classified into three groups based on the level of technology and the length of journey made: traditional, semi-industrial, and industrial. In this study, labor productivity in the traditional and semi-industrial groups were compared using data obtained from a sample of 35 fishermen in Bushehr Province. To determine the marginal and average labor productivities, transcendental production functions were estimated for fish and shrimp, separately. The findings indicated that the marginal and average productivities of labor in semi-industrial fishing were significantly higher than in traditional fishing.

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As apparent Zn recovery in mineral soils (saturated and unsaturated) is nill, the precise assessment of processes responsible for Zn retention in these soils is of great importance. A laboratory study was conducted to characterize Zn adsorption in eight lowland calcareous soils. The fit of sorption data was evaluated by Freundlich and Langmuir isotherms. In this study, 2-g soil samples were equilibrated for 24 hours with 40 mL 0.0lM CaCl₂ solution containing 5 to 500 mg Zn L^-1. The amount of Zn adsorbed was calculated based on the difference between the initial and equilibrium Zn concentrations.

Zinc adsorption data were fitted to a linear form of Freundlich equation. However the Langmuir isotherm was divided into two distinct linear portions, representing two different types of adsorption sites. The Langmuir K₁ was higher and adsorption maxima (b₁) was lower in part I (corresponding to lower Zn concentration) than in part II (corresponding to higher Zn concentration). Thus, it seems that in parts I and II, sites are more important for their high adsorption energy and adsorption capacity, respectively. Langmuir adsorption maxima (b₂) was positively correlated with clay content, CCE and P concentration and negatively correlated with CEC.

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In order to find the critical period of weed control, the best time of weed control beginning (i.e. herbicide application time), and the length of weed control period (i.e. herbicide persistency) in corn, field experiments were conducted in Bajgah and Kooshkak in Fars Province in 1995 using a randomized complete block design with 14 treatments and four replications. Treatments consisted of different times of weed control beginnings (20, 30, 40, and 50 days after corn emergence), different duration of weed control periods (10, 20, and 30 days), a weedy check, and a weed-free check during the period of corn growth.

 In Kooshkak, a 10-day duration of weed control period had significantly lower corn yields than 20 and 30-day periods. In Bajgah, a 10-day weed control period had significantly lower corn yields than a 30-day period. Time of weed control beginning was not significant at both locations however, the interaction between beginning time and the duration period of weed control was significant. It appears in both locations that a minimum 20-day control period at the initial stages of corn and weed growth, and a minimum 30-day control period before corn pollination are necessary to prevent corn yield losses. In order to prevent corn leaf area decline at both locations, a 20-day weed control period until 40 days after crop emergence is necessary.

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Diallel crosses of six breeding inbred lines of corn (Zea mays L.) were used to estimate combining abilities, heterosis and some other genetic parameters for yield and some of its components. Parents, 15 F1 crosses and 4 filler genotypes, were evaluated in a 5×5 simple lattice design. For all the traits studied, except seed length, the efficiency of lattice design was less than one. Therefore, data were analysed as a randomized complete block and after eliminating the filler genotypes, Grriffing’s method 2 with mixed B model was used in the genetic analyses.

General and specific combining ability (GCA and SCA) mean squares were statistically significant for all traits studied. The ratios of GCA to SCA mean squares were greater than one for all traits, except for the number of seed rows per ear, indicating the importance of non-additive gene effects in their genetic control. Low heritability estimates and degrees of dominance lower than one were further evidence of the presence of non additive gene effects for all the traits studied, except for the number of seed rows per ear. Therefore, production of single cross hybrids in order to take advantage of non-additive gene effects is of prime importance for grain yield, number of seeds per ear row, l00-seed weight, seed length, ear length, and comb percentage. For genetic improvement of number of seed rows per ear, selection methods for parental lines will be more efficient. In the hybrids studied, number of seed per ear row and l00-seed weight played a more important role in the observed variations in yield. In general, hybrids 4×5 and 5×6 with high SCA for number of seed per ear row, l00-seed weight and grain yield were considered favorable for the conditions of this study.

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In order to determine the most suitable cultivar and N level based on yield and silage value of forage sorghum, an experiment was conducted in summer 1995. The experiment was arranged in a split-plot design with four replications. Two levels of N (300, 500 Kg/ha urea) were the main plots and the subplots were three sorghum hybrids (Sugar graze, Super dan and Speed feed). Seeds were hand sown on June 29 with an inter row space of 50 cm and a final density of 20 plant/m².

The results showed that when the N rate increased, forage yields and percent of protein in forage and silage increased. Also panicle dry weight increased at anthesis. The N rate had no significant effect on other traits. A significant difference was observed among hybrids for all characteristics measured. Sugar graze with a bigger stem diameter was taller and produced higher number of leaves. At anthesis, plant leaf and stem dry weight was also highest for Sugar graze however, the highest panicle dry weight belonged to Speed feed. There was a significant interaction between hybrids and N levels for dry matter production. The percent of leaf, stem and panicle dry matter was highest in sugar graze, Super dan and Speed feed, respectively. The Sugar graze produced the highest forage and dry matter yield. This hybrid produced 30 ton/ha of dry matter and 97 ton/ha of forage, respectively.

 Furthermore, this cultivar had the highest percent of forage crude protein (7.45%) and the least percent of forage crude fiber (25.12%). Ensiling caused a decrease in percentage of crude protein and an increase in crude fiber. The Sugar graze and Speed feed had the highest and lowest dry matter digestibility, respectively. Based on the results obtained from this study, Sugar graze was found to be the most suitable hybrid due to its highest forage and dry matter yield and better silage quality. Higher N rate (500 kg/ha) is also recommended for higher forage yield and higher percentage of protein.

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Obtaining high seed and oil yields of sunflower requires coincidence of vegetative and reproductive stages of growth of the plant with suitable environmental conditions via selecting appropriate planting date. Since the suitable date of planting for sunflower cultivars under Isfahan environmental conditions was not determined, this experiment was conducted in 1996 at the Agricultural Research Station, Isfahan University of Technology. In this study, five dates of planting (April 27, May 12 and 27 and June 12 and 29) and three open pollinated sunflower cultivars (Record, Vnimik 8931 and Armavirec) were evaluated using a randomized complete block design with split-plot layout in three replications. Date of planting was considered as the main plot and cultivars were randomized in the sub-plots.

Number of seeds per head (SH), l000-seed weight (SW), seed oil percent (SOP) and, consequently, yields of oil (OY) and seed (SY) were significantly reduced as planting was delayed. Reduction in these traits were considered to be related to the coincidence of vegetative and reproductive growth stages with higher temperatures prevailing at later plantings. Vnimik 8931 had higher SH and SW, and thus produced higher SY. This cultivar had lower SOP than Record, but produced higher OY than Record due to its higher SY. Armavirec was ranked the least for the measured traits, except for its SH that was slightly higher than that of Record. SH was the most contributing trait to the increase in SY, and SY was the most determining trait for the increase in OY. Date of planting by cultivar interactions for SH, SY and OY were significant. Nevertheless, the highest amount of the measured traits were obtained with Vnimik 8931 at the first planting date.