فصلنامه تحقیقات مهندسی کشاورزی
سال سیزدهم شماره 1 (بهار 1391)

Sulfur polymer concrete (SPC) is a construction material composed of melted modified sulfur cement (MSC) and fine and coarse aggregates. This research investigated the effects of the quantity of MSC and curing time on the mechanical and physical properties of SPC. Samples were prepared using five levels of MSC and four curing times. The MSC used contained olefin hydrocarbon polymeric additive and the aggregates were those commonly used for conventional concrete. The mechanical and physical properties of the samples (compressive strength, yield point and Young's modulus, unit weight, voids in the aggregate and concrete air content) were determined. The results showed that increasing in the amount of MSC up to a specific threshold value (depending on aggregate gradation) improved the mechanical properties of samples. Beyond the threshold point, a decreasing trend was observed. The SPC in the present study gained an average of 70% of its 28-day compressive strength by three days from concrete placement. The greatest 28-day compressive strength was achieved using the densest aggregate gradation, a sufficient amount of MSC to fill voids in the aggregate and the maximum unit weight of SPC.

This study evaluates the effect of irrigation method on the water use efficiency and yield of onions at the Zahak agricultural research station in Sistan province. The testing was conducted using a split plot arrangement and a randomized complete block design with three replications during the 2005-2006 crop seasons. Irrigation methods were basin and drip tape irrigation and the irrigation levels tested were 100% (T1), 75% (T2) and 50% (T3) of the water requirement of the plants. Analysis of data from two years of study showed that a change of basin irrigation to drip tape significantly increased the performance of the bulb. The maximum bulb weight and height of the plant was significantly influenced by irrigation type and amount on all levels. A comparison of the mean performance showed that full irrigation produced the greatest amount of bulbs (24.75 ton\ha). It also showed that the amount of water used for the drip tape treatment 3.86 kg/m3 was significantlygreater than for the basin irrigation method (2.80 kg/m3). There was a small significant difference between irrigation treatments with the highest value for both treatments shown for T2.

Lysimeter tests were conducted on shallow groundwater that supplies part of the maize water requirements to determine crop yield. Twenty-four 0.8 m diameter lysimeters were buried in the test field at a depth of 1.2 m. The lysimeters were filled with the field soil (silty loam) and planted with summer maize. The groundwater depth in the lysimeters was set at 0.6 m using Marriotte bottles. Three groundwater salinity levels (2.5, 5 and 7.5 dS/m) at deficit and full irrigation levels (70% and 100% of evaporation from pan class A before irrigation, respectively). The water was replenished on a weekly basis. A factorial experiment was used in a randomized complete block design with three replications. The control treatment was maize planted and watered with full irrigation and no ground water. The results indicated that the percent of groundwater contribution at full irrigation for the three salinity treatments were 5.28, 4.61 and 3.76, respectively. For deficit irrigation, the results were 25, 22.09 and 19.71, respectively. All differences were significant for the 0.05 Duncan multiple range test. For deficit irrigation, the grain yield was 23.6, 28.3 and 30.1 % less, respectively, than for the control for the three salinity treatments. Dry matter was 33.2, 35.8 and 36.6 % less, respectively, than for the control. At full irrigation, the grain yield was, respectively, 19.2, 25.6 and 22.2 % reduced and the dry matter was 25.6, 31.2 and 24.5 % less than for the control. At full irrigation, the groundwater contribution decreased as the groundwater salinity increased. Lower evaporation from the soil surface may cause decreased amounts of salt rising into the root zone, resulting in an increase in relative yield.

Samanoo is a traditional Iranian dessert that has a high nutritional value. Its consumption is on the rise. Samanoo is made using a mixture of wheat sprout extract (wheat malt) and whole wheat flour. It is mainly prepared at home or at in small businesses and there is no standard method of preparation. This study investigates the effects of wheat cultivar (Hirmand and Tabasi) and the ratio of wheat flour to the weight of the wheat sprouts (2:1 and 3:1) on physicochemical (total sugar, reduced sugar, pH, acidity, protein, ash content, color, brix, moisture content, water activity), sensory, and rheological properties (flow behavior, apparent viscosity, time dependency) of samanoo. In addition, the impact of storage (50 days at 3°C) on the pH, acidity, and growth of molds was determined. Results showed that wheat cultivar and wheat flour ratio and their interaction had significant effects on most properties (p < 0.05). Based on these findings, samanoo made using the Hirmand cultivar with a mixing ratio of 1:2 achieved the best scores in terms of quality.

This study determined optimum conditions for drying pomegranate arils in a solar dryer. A cabinet solar dryer was used in active and mixed modes. The response surface method was employed with nine treatments (runs) and a control run (3 m/s air velocity and 2 cm in thickness) and five replications. The Bryte cultivar was tested and samples were dried to approximately 10% moisture. Drying time, vitamin C, color, acidity, and microorganisms were evaluated in the samples. The effects of thickness and air velocity on drying time and all qualitative factors were significant except for acidity and taste (p < 0.05). Drying time, yellowness (b factor in color) and microorganisms increased as thickness and air velocity increased. Brightness (L factor in color), redness (a factor in color), and vitamin C decreased with as thickness and air velocity increased. The quality of the dried products in the solar dryer was much better compared to the sun-dried control samples. Samples 0.6 cm in thickness with 3 m/s air velocity had the best quality in the solar dryer. Their drying time decreased 85% in comparison with sun drying.

This study estimated the effects of thermal treatment (3 days at 36°C) and the fungicide biphenyl (immersion in 4% biphenyl for 2 min) on shrink wrapping, quality and shelf life of tangerines in Jiroft. The testing was done in two locations (a warehouse and refrigerated storage) over three months. The rate of solid material in the juice (TSS), acid (TSS/Ta), hardening of tissue, color and freshness of fruit in all treatments were measured after 60 and 90 days and after the fruit was removed from the warehouse. Results show that 60 days of storage in the warehouse using fungicide and shrink wrapping was the best treatment. The best result for TSS/Ta was 90 days of refrigeration with the polyethylene cover. The best fruit color was produced with refrigeration for 60 days using shrink wrapping. The best results for tissue hardening and freshness of fruits was achieved with refrigeration for 60 days of treatment using shrink wrapping.

In this study, the effect was evaluated of thresher drum rotary speed (700, 800, 900, 1000 rpm), distance between thresher drum sieve (8, 10, 12, 14 mm) and stem height (50–60, 61–70, 71–80 cm) on the percent breakage into chipped kernals, half kernels, bits and fine particles. A Lexion 510 class combine harvester was used equipped with GPS and yield monitoring equipment. A randomized complete block design and split factorial arrangement with three replications and a Duncan test was used for statistical analysis. Testing was done at a Pasargad farm in Fars province. Marvdasht variety wheat was planted using an Amazon combinat. The results showed that the drum rotary speed had a significant effect on threshing loss and percentage of damaged grains. The best result was produced by a thresher drum rotary speed of 700 rpm, 10 mm distance between thresher drum and sieve and a stem height of 71– 80 cm.

South Khorasan province is the largest producer of barberries in Iran and the world, with 14000 hectares and 98.7% of the national barberry production. Knowledge of harvest timing, proper harvesting and drying methods increase the quality and improve the status of barberries on the domestic and global markets. This study investigated the effect of harvesting method (striking, picking up bunches, cutting branches), harvesting time (mid- October, late October and mid-November) and drying method (drying in shade, drying in sun, industrial dryer) on product quality. The results showed that the mass density of dried barberries is influenced by harvesting and drying methods. Cutting branches caused the lowest mass density (214.86 kg/m3). The lowest colorimetric quality samples were produced by drying in the sun after the first harvest time and the best quality was produced by drying in the shade after the third harvest time. Results showed that drying in the sun and industrial drying methods reduced the color quality of the product. The results of sensory tests confirmed that the best quality samples were harvested by picking up bunches at the second harvest time and shade drying. The lowest assessment was for samples harvested by striking at the first harvest time and sun drying.