Showing 1096 results for Ro
V. Karimi, A.a. Kamkar-Haghighi, A.r. Sepaskhah, D. Khalili,
Volume 5, Issue 4 (1-2002)
Abstract
Drought can occur at such times when variables such as rainfall depth, run-off, soil moisture, etc. show a deficiency, or variables such as temperature show an increase, or when ground water level shows a decrease in comparison with the average level. Therefore, drought can be evaluated with respect to agricultural, meteorological, or hydrological variability. In this research, considering the meteorological aspects, the method by Herbst et al., later modified by Mohan and Rangacharia, was applied in drought evaluation in Fars Province, Iran. Monthly rainfall measurements over a period of 21 years for 51 stations obtained from Fars Regional Water Board, were used in the analysis. Maps showing lines of iso-duration and iso-intensity lines were developed for the province. Based on the results, northeast, southeast, south, and southwestern parts of the province have the highest potential for being affected by drought events.
M. J. Arvin, N. Kazemi-Pour,
Volume 5, Issue 4 (1-2002)
Abstract
A glasshouse study was conducted to measure the effects of salinity and drought stresses on growth and chemical and biochemical composition of 4 onion cultivars. The cultivars were Dessex, Texas Early Grano (Texas), Dehydrator, and PX492. Salinity treatments included control, 45mM NaCl, 45mM NaCl + 5mM CaCl2 and drought treatments were control (maintaining soil moisture at field capacity) and irrigation when 50% of available water was used. Four weeks after the treatments, the plants were harvested and root and shoot dry weights (RDW, SDW), Na+, K+, Ca2+, total protein, reduced sugars, as well as free proline contents were measured in both roots and shoots.
Results showed that NaCl and drought treatments significantly reduced SDW and RDW. The Texas cultivar and the Dessex cultivar produced the highest and the lowest amounts of SDW, respectively. NaCl significantly increased Na+ uptake but reduced K+ uptake in shoots and roots and also reduced Ca2+ uptake in roots. NaCl+CaCl2 significantly alleviated the deleterious effects of NaCl such that SDW significantly increased in two cultivars and increased RDW and the K+ contents while causing decreased Na+ and sugar contents in shoots and roots of all cultivars. All stresses increased total protein contents of shoots in Texas only but decreased or had no effect on others. Root total protein increased under salinity stress, while drought had no effect. Changes in proline and sugars in both shoots and roots did not follow any particular pattern. Out of the biochemical compositions measured, shoot total protein in plants under the stresses showed a positive significant correlation with SDW, which may be used to screen onion cultivars for drought and salinity stresses.
A. Ronaghi, Y. Parvizi, N. Karimian,
Volume 5, Issue 4 (1-2002)
Abstract
Nitrogen is usually the most limiting nutrient for crop production. Manganese deficiency in some calcareous soils of Iran has been reported. The objective of this study was to evaluate the effect of N and Mn on the growth and chemical composition of spinach (
Spinacia oleracea L.) under greenhouse conditions. The experiment was conducted in a soil from Chitgar series (Fine-loamy, carbonatic, thermic, Calcixerollic Xerochrepts). Treatments consisted of factorial arrangement of five N rates (0, 50, 100, 200 and 400 mg kg
-1 as NH
4NO
3) and three Mn rates (0, 15 and 30 mg kg
-1 as MnSO
4) in a completely randomized design with four replications. Plants were allowed to grow for 60 days and a hand-held SPAD-502 chlorophyll meter was used to evaluate leaf chlorophyll status at harvest.
Results showed that N and Mn application increased shoot dry weight, N and Mn concentrations and total uptake, Mn:Fe ratios and chlorophyll readings, significantly. Nitrogen increased concentrations and total uptake of Zn, Cu and total uptake of Fe in plants, but decreased Fe concentration. Addition of Mn decreased Fe and Zn concentrations in spinach but increased total uptake of Fe and Cu. When maximum dry matter was obtained, the chlorophyll meter reading was about 40. A similar study should be carried out under field conditions before the N and Mn fertilizer recommendations for spinach can be made.
G. Fathi, M. Mojedam, S. A. Siadat, G. Noor Mohammadi,
Volume 5, Issue 4 (1-2002)
Abstract
Effects of different levels of nitrogen fertilizer and cutting time of forage on grain and forage yield of barley (Hordeum vulgare L.) Karoon cultivar was studied during 1995-1996 at Ramin Agricultural Research and Educational Center, University of Shahid Chamran, Ahwas, by using a split plot design in randomized complete block with 4 replications. Main plots were assigned to five levels of N fertilizer (45, 90, 135, 180 and 225 kg N/ha) as urea fertilizer and subplots to three cutting times (no cutting, cutting forage at early stem elongation without removing reproductive meristem and cutting forage in the middle of stem elongation with cut reproductive meristem).
The effects of N rates and cutting time on grain yield were significant. Maximum yield was obtained with 281.6 g/m2 when crop plants received 90 kg N/ha and cutting time at early stem elongation and minimum yield was obtained (158.2 g/m2) with 45 kg N/ha and cutting forage in the middle of stem elongation. Interactive effect of levels of N and cutting time on spike number per m2, grain number in spike and grain weight were significant. Among yield components, spike number and grain weight showed the highest sensitivity to both. Different levels of N increased forage protein concentration and protein yield significantly, but delay in cutting time decreased protein concentration and increased protein yield. Results indicated that high levels of N could not compensate for the delay in cutting time of forage for grain yield. It was concluded that application of 90 kg N/ha and cutting time in early stem elongation was preferable for grain and forage production as compared to other treatments.
G. Saeidi,
Volume 5, Issue 4 (1-2002)
Abstract
Flax (Linum usitatissimum L.) is an oilseed and widely adapted crop. Oil of regular genotypes of flax is used in industry because of its unique fatty acid profile. New, mutant genotypes of flax have oils similar to sunflower oil which can be used as edible oil. This experiment was conducted to investigate the genetic variation of agronomic traits and productivity in different edible and industrial oil genotypes of flax in Isfahan. The genotypes were evaluated in augmented design.
Based on the results, the average numbers of seedling/m2 in edible and industrial oil genotypes were 178 and 367 with variation coefficients of 70 and 10%, respectively. Maturity also showed variation and varied between 89 to 116 days in edible oil genotypes and between 89 to 128 days in industrial oil genotypes. Plant height varied between 57 to 86 and 49 to 73 cm in edible and industrial oil genotypes, respectively. Seed yield also had considerable variations and varied between 429 to 2651 and 779 to 2389 kg/ha with variation coefficients of 35 and 25 in edible and industrial oil genotypes, respectively. Seed yield per plant showed a high and positive correlation with basal branches (r=0.77**) and bolls per plant (r=0.93**), but high and negative correlation with stand (r=-0.66**). Regression analysis revealed that approximately 96% of the variation in seed yield per plant was attributed to variation in bolls per plant, seeds per boll and seed weight and they were determined as the major yield components, respectively. Bolls per plant was the most important yield component and contributed to 87% of the variation for seed yield per plant.
M. R. Khajehpour, A. R. Bagherian Naeni,
Volume 5, Issue 4 (1-2002)
Abstract
It is believed that various types of field bean, including pinto, white and red, differ in adaptability to high temperatures and may, thus, differ in response to delay in planting. In order to evaluate this response, an experiment was conducted during 1996 at the Agricultural Research Station, Isfahan University of Technology, using a randomized complete block design with split-plot layout. Main plots consisted of four planting dates (April 28, May 13 and 28 and June 13) and sub-plots included four genotypes of common bean (red bean, c.v. Naz pinto beans, experimental lines 11816 and 16157 and a white bean, experimental line 11805).
Number of branches per plant, number of pods per branch and per unit area, number of seeds per pod of main stem and branch, number of seeds per main stem, per branch and per unit area, 100-seed weight and seed yield significantly reduced, while harvest index significantly increased by delay in planting and consequent increases in temperature and reduction in time for growth. The lower harvest index obtained with early planting was the result of the lower efficiency of the produced vegetative growth due to the coincidence of seed filling period with high temperatures. Pinto bean line 11816 ranked the highest for number of branches per plant and harvest index among the genotypes evaluated and produced the highest seed yield (3030 kg ha-1). Although red bean Naz ranked the highest for number of pods and seed per main stem and per unit area, it had the lowest harvest index and 100-seed weight and, consequently, produced the least seed yield (2254 kg ha-1). The results obtained indicate that delay in planting adversely affects bean seed yield. Pinto bean line 11816 may have higher yield potential among the genotypes studied at all planting dates under conditions similar to the present experiment. No specific relationship was observed between apparent seed characteristics and plant tolerance to heat.
S. M. B. Nabavi, A. Savari, Gh. H. Vosoughi, A. R. Nikouy,
Volume 5, Issue 4 (1-2002)
Abstract
To estimate the biomass and secondary production of macrobenthos in Khore-e-Mousa creeks, 216 sediment samples were taken. The sampling period started in 1996 and terminated in 1997. A bimonthly sampling strategy was adopted. The samples were taken by Van-Veen grab (0.1 m2) from the beginning, middle and end of each creek (Khor). To estimate the biomass of the macrobenthos, the Crisp method (1984) was employed. The standing crop was expressed as dry weight and ash free dry weight. For the measurement of secondary production, a dominant crustacean species Apseudes sp. was used.
The results indicated a low biomass per unit area in Khore-e-Mousa creeks. Maximum and minimum amounts of the standing crop were found to be in June (33.5 g DW/m2) and December (2.19 g DW/m2), respectively. Amongst all creeks, Douragh creek displayed the highest (24.93 g DW/m2) and Beehad the lowest (2.24 g DW/m2) standing crops. During the study period, 1483 individuals of Apseudes sp. were collected and grouped into 5 age classes according to Bhattacharya (Sparre, 1989) method. The secondary production was estimated to be 0.08 g/m2 ash free dry weight (AFDW). The production/biomass ratio (P/B), therefore, is calculated as 0.08÷0.18=0.44. Considering the ecological efficiency, (transfer efficiency) of different trophic levels which is about 10%, the fish production is estimated to be 2430 tons in Khore-e-Mousa area.
M. Bouyeh, J. Pourreza, A. H. Samie,
Volume 5, Issue 4 (1-2002)
Abstract
An experiment was carried out to determine the effects of different levels of lysine and protein on the performance of 240 Hy-Line W36 layers. Ten experimental diets were tested in a 2×5 factorial arrangement with a completely randomized design. Two basal diets (13 and 14% protein) were tested at different levels (10 and 20% lower than NRC, NRC and 10 and 20% above NRC recommendations). Dietary lysine levels were 0.56, 0.62, 0.69, 0.76 and 0.83%. During the three months of experimental period, egg production, egg weight, egg output, feed intake and conversion and lysine and protein intake were determined.
The results indicated that 0.76% lysine and more (10 and 20% above NRC recommendation) with 13% dietary protein led to significantly (P<0.05) higher egg production, egg output and better feed conversion, but there was no significant difference regarding egg weight. The difference in performance with different levels of lysine was lower in the 14% dietary protein than that in the 13% one. In the 14% dietary protein, the lowest level (0.56%) of lysine led to significantly (P<0.05) lower egg production and egg output and higher feed conversion. The best performance with the 14% dietary protein belonged to 0.62% dietary lysine (10% below NRC recommendation). The 14% dietary protein had significantly (P<0.05) higher egg production, egg output and feed intake than the 13% dietary protein, regardless of dietary lysine but there was no significant difference regarding egg weight and feed conversion. The best and most economical performance belonged to the 0.76% lysine and 13% protein diet. The results of this experiment indicated that reducing dietary protein and addition of lysine to the diets of post peak laying hens can obtain an equal performance to the higher dietary protein, thus reducing production costs.
Y. Ebrahim Nejad, J. Pourreza,
Volume 5, Issue 4 (1-2002)
Abstract
This experiment was carried out to study the effect of ionophore drugs (Salinomycin, Lasalocid and their combinations) on the performance of broiler chicks. Also their relationships with methionine (three levels) were evaluated. 1215 one-day-old commercial broiler chicks (Arian) were divided into 81 groups, 15 chicks per group, and tested in a completely randomized design with a 3×3×3 factorial experiment. Three drug types with three levels (0.0, the recommended level and 1.5 times the recommended level) of drugs and three levels (0.0, 0.1% and 0.2%) of supplemental methionine were used.
The results indicated that the effect of sex on plasma cholesterol and triglyceride, percentage of bone ash and percentage of abdominal fat was significant (P<0.0l). Drug type had no effect on the characteristics under study. Drug level influenced percentage of bone ash, percentage of eviscerated carcass, and percentage of abdominal fat significantly (P<0.0l), (P<0.01) and (P<0.00l), respectively. Also methionine level influenced cholesterol and triglyceride (P<0.0l) significantly. Interaction effect of drug type and drug level on plasma cholesterol and triglyceride was significant (P<0.05). Interaction effect of drug and methionine level on cholesterol and triglyceride was significant (P<0.0l). The results showed that levels of this drug influenced carcass composition and also supplemental methionine had no influence on the modulating effect of these drugs on carcass composition.
K. Tajadodi Talab, M. Shahedi, R. Shokrani, S. Dokhani,
Volume 5, Issue 4 (1-2002)
Abstract
Rice bran is the most important by-product of rice milling. It is a valuable source of edible oil in most rice producing countries. Rice bran oil is used in babyfood, biscuit, poultry, fish and farm animal feeds. The storage of rice bran without 'heat processing will result in hydrolysis and auto-oxidation of lipids, and to its decreased physicochemical, organoleptic and nutritional quality. Rice bran is rich in carbohydrates, free amino acids, lipids and different enzymes. The enzymes have destructive effects on the quality of rice bran components. Heat processing is an effective method to reduce the microbial and enzymatic activity of bran.
This study was carried out using a factorial experiment by completely randomized design with three replications to investigate the effect of heat treatment and storage time on rice bran crude oil properties. The parboiling treatment was effective on the rice kernel strength. The bran produced from parboiled rice milling had lower endosperm components. This type of bran had a lower starch but a higher oil percentage. The results of color of rice bran oil samples determined by Lovibond showed that the oil from parboiled rice bran before and during storage had better color than the other samples. Iodine value of bran oil from parboiled paddy decreased during the storage period. The results from studies on fatty acid composition of oil samples determined by gas chromatography (G.C.) showed that the quantitative trend of fatty acids of the control sample remained the same as that in the rice bran samples with the treatment process.
M. Javan Nikkhah, Gh. A. Hejaroud, A. Sharifi Tehrani, S. A. Elahi-Nia,
Volume 5, Issue 4 (1-2002)
Abstract
Rice bran is the most important by-product of rice milling. It is a valuable source of edible oil in most rice producing countries. Rice bran oil is used in babyfood, biscuit, poultry, fish and farm animal feeds. The storage of rice bran without 'heat processing will result in hydrolysis and auto-oxidation of lipids, and to its decreased physicochemical, organoleptic and nutritional quality. Rice bran is rich in carbohydrates, free amino acids, lipids and different enzymes. The enzymes have destructive effects on the quality of rice bran components. Heat processing is an effective method to reduce the microbial and enzymatic activity of bran. This study was carried out using a factorial experiment by completely randomized design with three replications to investigate the effect of heat treatment and storage time on rice bran crude oil properties.
The parboiling treatment was effective on the rice kernel strength. The bran produced from parboiled rice milling had lower endosperm components. This type of bran had a lower starch but a higher oil percentage. The results of color of rice bran oil samples determined by Lovibond showed that the oil from parboiled rice bran before and during storage had better color than the other samples. Iodine value of bran oil from parboiled paddy decreased during the storage period. The results from studies on fatty acid composition of oil samples determined by gas chromatography (G.C.) showed that the quantitative trend of fatty acids of the control sample remained the same as that in the rice bran samples with the treatment process.
A. Jozyan, R. Ebadi,
Volume 5, Issue 4 (1-2002)
Abstract
In order to study the efficacy of Sunn pests' parasitoid flies, four overwintering sites of Sunn pest in Isfahan, including mountains of Kolahghazy, Panjeh, Jozdan and Sacepid were selected and from each site four different elevations were designated as sampling sites. During 1997, at least 6 and, in 1998, three samples were taken at each sampling site. In spring 1998, four wheat and barley fields were selected from Mahyar, Zeyar, Shahinshahr and Lavark regions and from each field eight samples were taken. In order to observe the larvae of parasitoids and to determine their efficiency, 100 Sunn pests were dissected from each sampling unit of aestivation, overwintering, wheat and barley fields.
The parasitism of prevalent species (Phasia subcoleoptrata L.) in spring 1998 was 15.39% for the 1st generation and 1.5% in 1997 and 3.5% in 1998 for the second generation of the pest. All other parasitoid species parasitized less than 1% of the pest population. In some regions, such as Lavark and Zeyar, chemical application against nymphs of Sunn pest were accomplished in spring 1998 at the peak of adult activity of parasitoids' 2nd generation. This application had negative effects on the population of parasitoids but in Shahinshahr where chemical application was accomplished at pupal stage of parasitoid, it did not have any direct adverse effects on the population of dominant parasitoid.
A. Erfani, G.h. Haghnia, A. Alizadeh,
Volume 6, Issue 1 (4-2002)
Abstract
A field study was conducted at the College of Agriculture, Ferdowsi University of Mashhad, to investigate the effect of irrigation with treated municipal wastewater on the yield and quality of lettuce and some soil characteristics. Five irrigation treatments were applied to a clay loam soil, classified as fine loamy mixed mesic Calcixerollic Xerochrepts, in a randomized block design with 5 replications. The treatments consisted of T1 (Irrigation with treated wastewater over all growing season), T2 (Alternate irrigation with treated wastewater and well water), T3 (Irrigation with well water and application of cattle manure), T4 (Irrigation with well water plus fertilizer N and P), and T5 (Irrigation with well water only as control). Chemical analysis of well water proved to be a suitable source for agriculture.
The results showed that the yield was higher in T1, T2, T3 and T4 as compared to the control treatment. Maximum fresh and dry yields were obtained from T3 & T1 and T1 & T3, respectively. Plant tissue analysis showed an increase in macronutrients (N, P, K) and heavy metal concentrations in shoots and roots of lettuce in the first four treatments as compared to the control. In T1, iron concentration was maximum while that of cadmium was minimum. Furthermore, microbial contamination was considerably higher in T1 and T2. Soil analysis indicated that in plots treated with wastewater, electrical conductivity, total nitrogen, available phosphorus, soluble boron and heavy metal concentration increased. However, their values were all below international standards. More experiments seem to be necessary in this regard.
H. Ramazanpour, A. Jalalian,
Volume 6, Issue 1 (4-2002)
Abstract
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 Feo (amorphous and organic-bound iron) was higher in surface horizons, whereas, the Fed (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 Fed-Feo, 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.
D. Qujaq, S.e. Mousavi,
Volume 6, Issue 1 (4-2002)
Abstract
The objective of this investigation is to measure pectinesterase activity by a simple method. The assay is done at 25°C. Oranges were obtained at a local supermarket in winter. They were peeled and 5 gr sections of the peeled tissue were homogenized in 10% NaCl and 0.5 M phosphate buffer in a homogenizer. The homogenates were centrifuged at 3500 rpm for 20 min. The supernatants were collected, their pH levels were raised to 7.25 using NaOH and the reaction was monitored at 485 nm in a spectrophotometer. The activity of pectinesterase was expressed as micromoles of methanol released per minute.
The results show that this method is reliable, sensitive, and capable of measuring pectinesterase activity of as low as 0.05 unit. The assay method proposed is a very useful analytical tool for the determination of the activities of pectinesterase.
M. Niknejad Kazempour,
Volume 6, Issue 1 (4-2002)
Abstract
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.
S.a. Safavi, Gh.r Rassulian Etal,
Volume 6, Issue 1 (4-2002)
Abstract
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. Ro 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.
G.a. G. A. Sharzei, M.a. M. A. Ghetmiri, M. M. Rastifard,
Volume 6, Issue 1 (4-2002)
Abstract
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.
M. Khalaji Pirbalouty, A.r. Sepaskhah,
Volume 6, Issue 1 (4-2002)
Abstract
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.
M. Shivazad, H. Janmohamadi,
Volume 6, Issue 1 (4-2002)
Abstract
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.
