JWSS - Journal of Water and Soil Science

---

The main objective of the present study was to investigate the production and marketing of Iranian saffron. About 99% of Iranian saffron is produced in Khorasan Province. Therefore, Khorasan was selected for the current study. Data were collected through the stratified random sampling method from 232 saffron producers in Torbat Heidarieh, Ghaenat and Gonabad regions through interviews in fall 1999. The production functions of saffron were estimated by using transcendental forms for the three study regions. Technical efficiencies for saffron producers were estimated using transcendental stochastic frontier production functions. Finally, wholesale, retail and marketing margins as well as marketing efficiency were estimated.

The results of the current study revealed that farmers were not using some of the inputs optimally. Study of the technical efficiency of saffron growers indicated that there was a considerable possibility of increasing production by increasing farmers’ efficiencies. The average of wholesale, retail and marketing margins of one kilogram of saffron were estimated to be 483, 410 and 893 thousand Rials, respectively, in the three study regions. Also, marketing efficiency was calculated at 155%. Finally, a marketing channel as a part of marketing strategy was proposed for Iranian saffron.

---

In order to compare the effect of drip and furrow irrigation methods with different quantities of water (50%, 75%, and 100% of the amount of water evaporated from class A pan evaporation during irrigation intervals) on yield and quality of tomato, an experiment was conducted on a silty loam soil in Mashhad Agricultural Research Station. The experimental design was a factorial trial with completely randomized blocks and. four replications.

The results showed that the highest yield (51 t/ha) was obtained from the treatment of drip irrigation with 100% water application. This amount was 4.5 tons higher than the yield from furrow irrigation treatment. Deficit irrigation by 25 and 50 percent decreased total yield by 34.7% and 67.95% in the drip irrigation method and by 27.57% and 64.29% in the furrow irrigation, respectively. Water use efficiency in drip irrigation was two times higher than that in the furrow treatment. Quality and chemical composition of the fruits were not significantly different in the two irrigation methods. Increasing the water deficit, however, increased the amount of soluble solids of the fruits.

---

The main objective of the present study is to analyze the effects of agricultural crop insurance on farmers’ technical efficiency and risk attitude. Required data came from questionnaires that were completed by the Institute for Planning and Agricultural Economics of the Ministry of Agriculture. Farmers’ technical efficiency and attitude toward risk were estimated using stochastic frontier production function and equally likely certainty equivalent method for both insured and non-insured groups. Results revealed that effects of agricultural insurance on farmers’ technical efficiency were significantly positive in the three study regions.

Results of estimating risk aversion coefficients of study farmers showed a positive effect of insurance on risk aversion coefficients. However, this effect was significant only in two of the climatic regions under study.

---

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.

---

The main objective of the present study is to investigate the production and marketing of fresh figs in Garmsar Region. Semnan Province has the largest area under fresh figs in Iran. About 84 percent of this area is in Garmsar region, hence, it was selected as the study area. Data were collected by random sampling method through interviews with a sample of 70 fresh fig producers in Garmsar region in summer 1999. The production functions of fresh figs were estimated using translog form for the study region. Technical efficiencies for fresh fig producers were estimated using translog stochastic frontier production function. Results of the current study revealed that farmers are not using some of the inputs optimally. Study of technical efficiency of fresh fig producers did not show the possibility of increasing production by increasing farmers’ technical efficiencies. The average of retail, wholesale and marketing margins of one kilogram of fresh figs were estimated to be 900, 550 and 1450 Rials, respectively. Also, marketing efficiency was calculated as 151%.

---

In order to investigate the effects of different nitrogen fertilizer levels and water stress during milky and dough stages on grain yield, yield components and water use efficiency of corn hybrid SC 704 (late maturing, non prolific and dent type), a field study was conducted. The factorial design of the study comprised of a randomized complete block with four replications. Four levels of nitrogen fertilizer (0, 92, 184 and 276 kg/ha nitrogen) along with three levels of irrigation (water stress imposed at milky stage, dough stage and a season-long optimum irrigation) were used as treatments. Results showed that water stress during milky and dough stages significantly decreased grain yield and thousand kernel weight. Also, effect of nitrogen fertilizer on grain yield, kernel number per ear, kernel weight per ear and thousand kernel weight was significant. Maximum grain yield was produced with 276 kg/ha nitrogen, although no significant differences were found among 92, 184 and 276 kg/ha nitrogen levels. Regarding water use efficiency during water stress, maximum efficiency was observed at milky stage but, as water stress declined with optimum irrigation, water use efficiency decreased.

---

Three potato cultivars (Solanum tuberosum L.), spring Marfona, autumn Cosima and Marfona, obtained from Isfahan Province, were stored under different conditions: 4^oC, darkness 12^oC, fluorescent light room temperature, darkness and room temperature, daylight. Relative humidity of the above stores was 85 to 90%. Analyses were carried out to determine total glycoalkaloids, α-solanine, specific gravity and total solids, during 30 days for the spring cultivar and 90 days for the autumn cultivars in stored tubers. α -Solanine content of each cultivar was determined by HPLC, in mg per 100 g dry weight, at the beginning, the midinterval, and the end of storage periods. Also, amounts of α-solanine in autumn cultivars, which showed the highest levels after storage for sixty days, were determined before and after heat processing for frying and cooking. Data were analyzed statistically by completely randomized design with Duncan’s multiple range test. The results revealed that the amount of α-solanine of the spring cultivar considerably increased under 12^oC and flourescent light as compared with the other storage conditions. The amounts of α-solanine considerably increased during the storage of autumn cultivars which were stored at 12^oC under flourescent light compared with those stored at room temperature and daylight, room temperature and darkness, and at 4^oC and darkness, respectively. The amount of α-solanine decreased due to spring conditions during the storage period for cultivars stored at room temperature and darkness. In spite of the decreasing effect of peeling, before frying and after cooking, frying and cooking processes had no effect on the amount of α-solanine in the samples. Therefore, according to the above results, the most appropriate storage conditions to prevent increasing effect of α-solanine in potato tubers was 4^oC in darkness.

---

In this study, efficiency of apple producers in Khorasan Province was determined by a cross sectional data of 212 apple producers. Mean technical, allocative, and economic efficiencies were estimated to be around 31, 28, and 9 percent, respectively. A high potential was also detected for increasing these efficiencies. Apple producers’ age and education had positive effects and risk aversion had a negative effect on technical efficiency. Waste reduction, optimal use of inputs, introduction of technical-extension services, and apple insurance are suggested to increase efficiencies.

---

The changes of main sugars and organic acids of Red delicious and Golden delicious apples from Semirom region in Isfahan Province were determined by high performance liquid chromatography (HPLC). The apples were harvested, graded and packed in three kinds of wood, car-board and perforated polyethylene film packages and stored for eight months at 0±0.5^oC and 90 to 95% relative humidity for further analysis. Sucarose, glucose and fructose, as well as citric and L-malic acids were detected and quantified in all packed samples. The obtained data were analyzed with factorial experiment in completely randomized design and mean were compared by Duncan^,s muliple range test. The results showed that fructose was dominant in both cultivars in all packages compared to other sugars. Golden delicious apples contained more sucrose and less glucose than Red delicious. All sugars decreased in packed apple samples during the storage period. The dominant organic acid of both cultivars was L-malic. Citric acid increased to its maximum level in Red or Golden delicious after one or two months of storage, respectively, and then decreased gradually by the end of storage period. In general, apples kept in perforated polyethylene films exhibited the best physiochemical properties during eight months of cold storage.

---

This study was conducted to determine the problems of marketing channels of damask roses and to seek appropriate solutions to enhance marketing efficiency. The results of the study revealed that traditional and industrial rose production lacked the quality demanded by the market. The efficiency index was % 92.9 in traditional and %55 in industrial production. In addition, with regard to the marketing parameters for each type of production, the share of the factors was calculated. So we can conclude that the reducing units have the most important roles in this process. According to the study, traditional units with %47.2 had a greater share compared with the industrial units (%44.5). The results have also shown that production retailer wholesalers and middlemen shares were in the lower ranks respectively. Marketing cost coefficient results showed that %70 of the retailer selling price for 1 kg of the product was related to the marketing costs. The costs for industrial units with high and low capacity were %67.7 and %65.4, respectively.

---

This study was conducted to evaluate the effects of four levels of irrigation (irrigation of plants after I₁ = 40, I₂ =60, I₃ = 80 , and I₄ = 100mm of evaporation from class A pan) and four plant densities(D₁ = 30, D₂ = 40, D₃ = 50 and D₄ = 60 plants/m²) on the seed yield and seed quality in three soybean cultivars(V₁=Hobit, V₂=Williams and V₃=Hill) in a split factorial design, based on the completely randomized blocks, with three replication for two years(2001 and 2002). The Irrigation treatments were assigned to the main plots, and the plant densities and cultivars to the sub plots. Results indicated that soybean seed yield was influenced by the different irrigation and plant density levels in the both years. Irrigation levels I₂ produced the highest and I₄ the lowest seed yield. It was also revealed that the plant density D₃ produced the highest and D₁ the lowest seed yields. Among the cultivars under investigation, V₂ produced the highest and V₃ the lowest seed yield . Seed oil and its protein contents both were affected significantly by the irrigation levels, plant densities and cultivars in both years. The plants receiving I₁ treatment had the highest and those having I₄, the lowest percentages of seed oil. Changes in the plant densities also affected seed oil and protein content. The plant density of D₁ caused the seeds to have the highest oil and lowest protein percentages. However, D₄ decreased oil and increased protein percentages. The highest water use efficiency was obtained from I₃ and that of the lowest value from I₁. The results also indicated that D₄ had the highest and D₁ the lowest water use efficiencies. Therefore, it could be concluded that the water use efficiency can be increased by increasing the plant density per unit area. The highest efficiency for biological and grain yield belonged to V₂ and V₁ respectively where as the lowest efficiency for those two mentioned characters belonged to V₁ and V₃, respectively. However, the treatment I₂V₂D₂ is recommended for higer the seed yield production per unit area.

---

Studies show that excessive rotation of rice, when the grains revolve inside the milling chamber, increase the breakage. Ease of grain movement in the milling chamber could minimize this problem by utilizing screw conveyor at the first part of rotor. In this study the rotor of a conventional milling was equipped with a screw conveyor. The effects of two rotor types (modified and conventional rotors), three output rates (412, 654 and 915 kg/h) and three blade distances from the agitator (11, 12 and 13mm) were examined on indices of rice quality using a split-split plot design. In this experiment, the percentage of whole white rice and breakage, degree of milling and milling performance index were either measured or calculated. Results showed that only the effect of blade distance on percentage of breakage was significant whereas the effect of feed rate on all measured parameters was significant. In addition, the interaction effects of rotor type and blade distance, rotor type and feed rate on percentage of whole white rice and breakage were significant, respectively. The milling performance index showed that the best conditions for both rotors can be obtained at output rate of 412kg/hr and 11or 12mm blade distance from the agitator. For this adjustment, the average of percentage of breakage in the modified and conventional rotors were 20.5 and 23, respectively.

---

In Iran, fertilizers are mainly applied directly to soil. In such conditions, the yield and fertilizer use efficiency are usually low. The simultaneous application of fertilizers and irrigation water (fertigation) is an appropriate alternative to increase the efficiency of applied water and fertilizers. The objective of this study was to investigate the effect of various irrigation and fertilizer amounts on efficiency of applied fertilizers when used as fertigation in a Tape irrigation system. A field experiment was carried out with sunflower as a completely randomized design with 20 treatments and 3 replicates. The fertilizers were applied by fertigation. Four levels of the water (60, 80, 100 and 120% treatments I1 to I4) and five rates of the recommended fertilizers (0, 60, 80, 100, and 120% treatments F₀ to F₄) were applied.The recommended amounts consisted of 400 kg CO(NH₂)₂, 50 kg KCl, 30 kg FeSO₄, 30 kg MnSO₄, 50 kg ZnSO₄, 30 kg CuSO₄, and 30 kg H₃BO₃ per ha. Tape irrigation was used for every treatment. The results indicated that in fertigation method, there were significant differences ( P≥0.01) in fertilizer use efficiency (FUE) for the total dry matter and grain yield between treatments. The results showed that by increasing applied water, fertilizer use efficiency was increased and affected by fertilizers treatments. Thus due to higher availability of nutrients, fertilizer use efficiency increased. was Fertilizer use efficiency also decreased by increasing fertilizer rate. The results also demonstrated there were significant differences in all the treatments. The results showed that fertilizer use efficiency of K is higher than N and N is higher than P.

---

Understanding the nitrogen remobilization by plant, in order to obtain cultivars with higher quality, has specific importance in plant physiology. In this experiment, a bread and a durum wheat cultivar, were treated with different rates and times of nitrogen application, by using split factorial on the basis of randomized complete block design with three replications at Shiraz region during 2001-2002. Main plots consisted of two levels of cultivars ( Falat and Yavaros) and sub plots included nitrogen (40, 80 and 160 (kg ha^-1) and times of nitrogen application (T1= all N fertilizer at planting , T2= 1/2 at planting + 1/2 during stem elongation and T3= 1/3 at planting + 1/3 during stem elongation + 1/3 at heading stage). The results showed that there was a significant difference between cultivars in flag leaf nitrogen content at maturity stage, N remobilization and its efficiency from flag leaf to grains and also grain protein percentage. Durum wheat was more efficient in nitrogen remobilization and therefore, had a higher grain protein percentage. Increase in rates and times of nitrogen application had significant effect on most of the measured traits. There were significant interactions between cultivars, rates and times of N application, indicating that durum wheat was more efficient in N remobilization from flag leaf to the grain. It appeared that N remobilization efficiency was the important factor affecting the grain protein percentage. Also increases in yield are associated with corresponding decreases in wheat protein.

---

The main objective of this study was determining the best sprinkler system and ranking total operational sprinkler systems in Isfahan province. The data was collected through 262 questionnaires completed by farmers in Feridan and Semirom cities in Isfahan province. Ranking and comparing the systems were done via criteria matrix and qualitative efficiency of objects and compromise programming. Based on the results of this study, hand-move sprinkler irrigation and then solid-set sprinkler irrigation were found to be the best systems in most of the regions. However, solid-set sprinkler irrigation was the best in some other areas. Results also showed that there were trivial differences between farmer selection in sprinkler irrigation and suitable system in the region. Also, comparison of suitable system and conventional irrigations used by farmers showed that the current systems of farmers are not usually an optimal system.

---

  A labyrinth spillway is an overflow spillway to regulate and control flow in canals, rivers and reservoirs. The main hypothesis for the development of such a spillway is to increase the discharge per unit width of structure for a given headwater. This type of structure is often an efficient alternative to a gated-spillway type where either the increase of the flood-passage capacity or the control of the water surface upstream is concerned. This study was aimed to investigate the hydraulic performance of labyrinth spillways of general trapezoidal planform with simple curved apexes. In the experimental work, twelve spillway models with double cycles were considered using three different curved apexes (R/w= 0.15, 0.2, 0.25), each with four different crest heights (w/P= 1.5, 2, 3, 4). Based on the cited recommendations, the length magnification was set to a constant ratio of (l/w= 3) the crest shape was to be of a semi-circular form with simple radius (r= 15 mm) and the spillway walls were vertical with the thickness of T= 2r. An intensive experiment was carried out over a wide range of flows, providing 720 flow data ranging from free flow to submerged flow conditions. 1D flow equation was presented using combined mathematical and dimensional analysis. A coefficient of discharge, C_d, was introduced to represent the influence of the effective geometric and hydraulic parameters on the flow capacity over the spillway. Modular limit was also controlled to see whether the flow over the spillway would be submerged. The results of the study indicate that the modified curved planform of the spillway apexes with consistent divergence in the downstream channel introduces a significant improvement in the flow efficiency over the labyrinth spillways. Spillways with narrower curved apexes (i.e. R/w≤ 0.2), and with the vertical-aspect ratio of (2≤w/P<3) provide more stable and higher hydraulic performance than any other labyrinth planforms over a wide range of flows (i.e. 0.10/P<0.6). In terms of the flow capacity, the proposed spillway model is shown to be more efficient than other zig-zag planforms (i.e. triangular and trapezoidal shapes) with an identical crest length.

---

To investigate yield and water use efficiency (WUE) of potato with tape and furrow irrigations, an experiment was performed at Hamadan Agricultural and Natural Resources Research Center (Ekbatan station) in 2004. The experiment was arranged in a split-plot experimental design based on completely randomized block with 3 replications of irrigation water amount as the main factor (75%, 100%, 125% of cumulative evaporation from class A pan) and sub-factor of irrigation method [including tapes in the middle of furrow ridge on soil surface (T_D0), tapes in the middle of furrow ridge at the depth of 5 cm (T_D5), tapes on the sides of furrow ridge on soil surface (T_S0), and furrow irrigation (F)]. The results indicated that yield of potato increased with increasing water use. Regardless of irrigation method, maximum (32.51 ton/ha) and minimum (19.33 ton/ha) yield of potatoes was achieved with 125% and 75% irrigation water treatments, respectively. The lowest yield (21.35 ton/ha) was obtained in furrow irrigation and the highest yield (28.91 ton/ha) belonged to tape irrigation (T_D5 treatment). The highest WUE (4.68 kg/m³) belonged to tape irrigation (T_D5 treatment) and the lowest WUE (3.32 kg/m³) belonged to furrow irrigation (F). The difference in WUE between 75% and 100% irrigation water treatments was not significant. The highest WUE (4.49 kg/m³) was achieved in treatment 125%. Also, it is more economical to use irrigation water treatment of 125%, as compared with other irrigation water treatments.

---

  Effect of change from the conventional (flooding) to subsurface irrigation system was studied on mature pistachio trees (Cultivar Ohadi) in Kerman pistachio research station for four years. This experiment was carried out in a randomized complete block design including 7 treatments and 3 replications. The experiment also used two irrigation intervals (7&14 days) and three water rates according to pan coefficient (20%, 40%& 60% evaporation from surface of class A pan) for subsurface irrigation system with 6 treatments the conventional (flooding) irrigation system was tested as control. The pipes of subsurface irrigation system were installed at 90cm distance from trees trunk at each side of trees, and 50cm from soil surface. Mean of pressure and discharge in the pipes was 0.8 to 1 atmosphere and 5.4 Lh^-1m^-1, respectively. Different factors of quantity and quality pistachio yield, current vegetative growth, water use efficiency and soil electrical conductivity were measured. The results showed that change of conventional (flooding) to subsurface irrigation system is possible and the best treatment can have water rate of 7174 m³ha^-1y^-1 with 14 days irrigation interval. In comparison with other treatments, this treatment has better quantity and quality pistachio yield. Water use efficiency (WUE) of this treatment was 164g dry yield per cubic meter. Nevertheless, application of water rate of 4783 m³ha^-1y^-1 can result in the deficiency of irrigation water. At this water rate, WUE was 177g dry yield per cubic meter. However, it was found that the application of lower water rate (<4783 m³ha^-1y^-1) produced severe effects on the treated pistachio trees, e.g. decreasing the growth rate, yield and increasing the early splitting in pistachio fruits. Finally, it is concluded that 14-day interval irrigation is the preferred treatment for pistachio trees. Also, soil salinity showed considerable change in subsurface irrigation treatments after irrigation system was changed, especially in the first year.

---

In tea plantation regions of northern part of the country, application of supplemental irrigation during dry periods (lacking rainfalls) in conjuction with proper nitrogen fertilizer application can significantly improve tea yield per unit of plantation area. In order to quantify the effectiveness of proper irrigation and nitrogen management on tea, the response of tea to various levels of irrigation and nitrogen applications was studied in Fouman suburb of Guilan province. Tea crop production function and its crop coefficient (K_C) were determined. A line source sprinkler irrigation was used for creatiating a variable irrigation application and a split-split-plot statistical design was used. Irrigation treatments consisted of full irrigation (I₄), deficit irrigation (I₃, I₂ and I₁) and no irrigation(I₀). Nitrogen application treatments were N₁, N₂ and N₃ (100, 180 and 360 kg/ha) in three replications randomly arranged as main plots, while irrigation treatments as sub plots were not randomized. During the growing period, soil moisture up to the depth of 90 cm was determined gravimetrically and actual crop water use was calculated from mass balance equation weekly. Reference evapotranspiration (ETo) was estimated by Penman-Montieth equation and was used to estimate tea crop coefficient. During growing period, the actual tea water use of I₄ and I₀ were computed to be 457 and 256 mm. Tea crop coefficient during dry period (June, July and Augest) ranged from 0.8 to 0.9. Crop resistance factor (K_y) for tea was found to be 1.37. Results indicated that optimum rate of nitrogen (180 kg/ha) along with supplemental irrigation, increased yield and water use efficiency (WUE). Futhermore, supplemental irrigation increased yield and WUE more than nitrogen application. In I₀ and I₁ treatments, application of 100 kg/ha nitrogen resulted the highest yield and WUE.

---

Iron deficiency is a worldwide nutritional constraint in agricultural lands especially in calcareous soils. Cultivation of crops tolerant to Fe-deficiency is an approach to combat Fe deficiency. The aim of this investigation was to evaluate Fe-efficiency of selected important crops in Iran. A completely randomized block design in triplicates was conducted at IUT research greenhouse in fall 2006. Sweet corn (Hybrid K.S.C. 404), grain corn (Hybrid S.C. 500), safflower (cvs. S3110, S-411), sunflower (Hybrid Hyson) and durum wheat (cv. Shuga) were grown in a nutrient solution at two Fe levels (1 and 10 µM Fe-EDTA). The results showed significant (P < 0.01) variation among the studied crops in Fe-efficiency. Corn hybrids were more sensitive to Fe deficiency (FeE = 26%) as compared to other studied crops, and the greatest reduction was observed in their shoot dry matter at 0.1 mM Fe- EDTA treatment. In contrast, the lowest decrease in root and shoot dry matter weight under Fe-deficient condition was found for durum wheat (FeE=94%). Comparing the calculated Fe-efficiency using different indices showed that Fe concentration and content in the whole plant, shoot and root had no relationship with crop tolerance to Fe deficiency.