JOURNAL OF AGRICULTURAL ENGINEERING RESEARCH
Year:2007 | Volume:8 | Issue:1|Papers Count:20

Apricot is climacteric and its ripening process is regulated by ethylene, therefore, inhibiting ethylene biosynthesis or action should slow the ripening process. This study was conducted to decrease materials losses and increase storage life of fruit by proper packaging. Different packaging (polyethylene film, polyethylene film with ethylene absorbent, shrink pack and control) were used. After 0, 15, 30, 45, 60 days of storage time fruit quality and sensors evaluation  were examined. A factorial experiment of design was laid out in completely randomized design with 4 replications for each one of stages. All the data were subjected to analysis of variance and Duncan’s multiple range tests to compare the treatment means. Results showed that the best packaging was polyethylene film with ethylene absorbent that could preserve fruit quality for 60 days.

Many mathematical models have been applied and developed for simulation of water and solute transport in irrigated agriculture. Using a model, it should be first calibrated and validated for different regions. SWAP is a field scale model that simulates water, solute and heat movement in the soil profile. In this study, the SWAP model was evaluated for two years (2001 and 2002) on wheat in a semi-arid area in North of Gorgan. Required data were collected by field experiments. The experiments were consisted of four water quantity levels (50, 75, 100 and 125 percent of crop water requirements) and four water quality levels including S1, S2, S3 and S4 having 1.6, 7.9, 10.8 and 13.6 dS/m in the first year and 1, 9.3, 12.2 and 14.7 dS/m in the second year, respectively. The experimental design was performed by randomized complete block design as a split plot layout with three replications. Based on statistical analysis, results from the simulation of SWAP model were in good agreement with the field measurements of water content (q), salinity (ECe) along the soil profile and wheat relative yield. In all cases, correlation coefficient (R), was higher than 80 percent and root mean square error (RMSE) was less than standard division (Sd). In the first year, bottom boundary condition was supposed to be free drainage, but due to fluctuations of water table in harvest time, model under predicted soil water content in 80-100 cm depth. Since the high frequency of rainfall (especially in second year) and elimination of deep percolation, the discrepancy between the measured and predicted ET was not satisfied.

This study was conducted to investigate the effects of irrigation frequency and substrates on some parameters of greenhouse tomato (CV. Hamra) during 1381-1382 at research greenhouse of agriculture college, in Ferdowsi University of Mashhad. The experiment was based on split plots in the form of completely randomized design and in four replications. Irrigation frequency in three levels of 12, 8, and 4 times per day at primary plots, and three substrates of Perlite, leca, and mixture of Perlite and leca at secondary plots. Parameters such as number of ties, ties spacing on main trunk, length and diameter of main trunk, dry weight of stem and leaf, number of fruits, and mean fruit weight were measured. Generally most of parameters, except crop production and mean weight of fruit per plant, did not influenced by different irrigation treatments. Mean weight of fruit and crop production were at their highest level under 12-day irrigation frequency. No significant difference was found for all of the parameters and under different substrates. The highest crop production and mean fruit weights were due to leca substrate and 12-day irrigation frequency. There were no significant differences as compared to 8-day irrigation frequency.

The aim of this research was to investigate performance of two combined plows compared to conventional plow. The experiments were conducted in a loamy soil texture with moisture content of 16-18% in Karaj region of Iran. Combination of moldboard + chisel plow and disk plow + chisel plow were compared with conventional moldboard plow as three treatments. Data was statistically analyzed using RCBD in three replications. Parameters of penetration resistance, bulk density, mean weight diameter and reversed residue percentage were measured or calculated and then analyzed. The results indicated that bulk density decreased 30.8% by moldboard + chisel plow particularly at depth range of 25-35cm. The results of penetration resistance (CI) confirmed the effect of this treatment on plowpan. Hence this combined machine can be recommended for a field with existing plowpan. Moreover diskplow + chisel treatment created the least clod size (MWD) in shallow soil layer. Therefore it can be recommend for reducing secondary tillage operation. The results of residue reversing noted that disk plow + chisel treatment left maximum of 68% crop residue. Therefore for conservation tillage system with residue reversing concern this combined machine is recommended.

In order to improve irrigation water productivity (WP) at rice production, a field experiment was conducted at Shahid Fozveh research station (Esfahan region) during 2001-2003. Experiment was arranged in a split plot design (RCBD) with three replications. The treatments were: three levels of irrigation managements including I1: permanent flooding under 3.5cm water during growth period, I2: permanet flooding under 2.2cm water during growth period and I3: 0-1.5cm alternative wetting and drying (AWD)) considered as main plots and eight advanced rice cultivars consisting Geredeh mahali, Zayandeh-rud, Sazandegi, Hasani, 67-97, 67-113, 67-47 and 67-72 as sub plots. The treatments were compared based on yield grain and water productivity for irrigation management and rice varieties. Results showed that maximum WP obtained from AWD irrigation management and Zayandeh-rud rice variety, its amount was 9.1 kg.mm-1. At this treatment with 33.4 percent reduction of water use, only 11.1 percent decreased paddy grain yield. Results showed that it is not necessary to maintain the rice field submerged in whole grouwth period.

In order to protect the color of dried pear slices from browning, a study was conducted using complete randomized factorial design with 4 factors and 3 replicates at agricultural research center in West Azarbaijan. The first factor was cultivar types including Shahmeive and Williams. The second factor was dipping time at 2 levels of 5 and 10 min. and the third factor was the concentration of acid at 3 levels of 0, 1 and 2%. Pear slices were then dried using direct solar drying method after treatment. The results analysis showed that, moisture content, acidity, pH and optic density of samples were significantly affected by cultivar types and acid concentrations. The mean comparison showed that, optic density or in the other words brown color formation of dried slices were significantly increased with acid concentration up to 1%, but there was no significant effect by increasing the acid concentration to 2%. The results of sensory evaluation also indicated that, the taste panel preferred dried pear slices which were produced from William cultivar. According to the results, it is recommended to use 1% of citric acid solution for 5 min in order to prevent the development of brown color in the slices.

In this study, performance of the two types of paddy separator (compartment type and tray type) on three prevelent paddy varieties (Kamfiruzi, Amol-3 and Nemat) were evaluated and compared in Fars province at a milling factory. A split plot design with five replications and Duncan’s multiple range test was used for statistical analysis. Three varieties of paddy and two types of paddy separator were selected as main plots and sub plots, respectively. Parameters such as percentage of paddy, brown rice, and rice breakage were measured by sampling from the outlet of husker, paddy separator and polisher in each treatment. Capacity and power requirement of paddy separators were measured and compared as well. The method of partial budgeting was used for economic comparison of two paddy separator types. Results showed that performance of the tray type paddy separator was better than compartment type in the three paddy varieties. There was a significant difference between the paddy separators from the view point of paddy percentage and brown rice. Tray type separator had more percentage of paddy 76.03% and brown rice 99.89% compared to compartment type paddy separator with 28.32% and 99.5% of paddy percentage and brown rice, respectively. Furthermore, rice breakage of tray type separator (18.34%) was significantly less than that of compartment type (21.75%). The capacity of tray type paddy separator was also one and half time as high as the capacity of compartment type, and the power requirement for compartment type was five times as high as the power requirement of tray type. Results of economic comparison showed that tray type paddy separator was proper for Amol-3 and Nemat varieties and compartment type was proper for Kamfiruzi variety.

In order to develop the pasture, soil conservation and increasing the soil infiltration by using the applicable methods such as agricultural machinery and no tillage or minimum tillage system are very important. In this regard, the husk properties as herbal mulch, and also the physical properties of species including Secale montanum, Festuca arundinacea and Bromus tomentellus, were studied. A mulch-planter was designed and then constructed, to place a band of mulch into the soil simply. Also planting seeds for developing of pasture land could provide an appropriate seed bed in the soil. For this purpose, a mechanism was constructed and installed on the machine, which could be able to plant seeds. The other advantage of mulch-planter was attaching to tractor three-point hitch, and used in no tillage system. The results of farm practices showed that using the machine was acceptable. This machine used two levels 1162 and 1744kg/ha of mulch and 6.7 to 18kg/hectare of species seeds. The forward speed of machine was 4km/h and the required energy was low. Three kinds of species, three amounts of mulch, and two depths of seed planting were examined. The results of the agronomic operations and application of mulch-planter with no tillage practices showed that the machine was efficient. At last, analysis of the data including number of growing plants and percentage of plant emerging showed that there was significant difference among factors. Use of mulch on species of Secale montanum seemed to be not advisable.

The Guelph Permeameter technique (GP) is a method for measurement of saturated hydraulic conductivity above the water table which has a strong theoric base and enable the experiments to be done with low cost and high speed. In this method soil's saturated hydraulic conductivity (Kfs) and matric flux potential (f m) are determined by Richard's two head analysis. In the Homogenous soils the result of the GP is satisfactory, but in the heterogeneous soils a high percentage of Kfs and fm values will be negative. GP analysis depended greatly on both the constant height of ponded water (H) and steady-state Q value in the hole. Therefore in this experiment the influence of increase or decrease of first and second ponding height (H1 and H2) on producing the negative values, in loam soils was studied. Results showed that the increasing H2 ratio to H1 caused a large number of Kfs and fm values to be positive, while there was no significant difference between their means.

The rotor of Enegelberg whitener was equipped with a screw conveyor to reduce broken rice percentage. According to preliminary experiments this modification could reduce broken rice percentage about 2.5%. Further experiment was performed to determine the effect of rotor speeds and blade positions on white rice quality. To do this, five rotor speeds, consisting 500, 600, 700, 800 and 900 r.p.m and three blade positions including, distance blade from entrance side of rotor was 7mm and from exit side was 9mm, distance blade from entrance side and exit side was 8mm equally, finally distance blade from entrance side of rotor was 9mm and from exit side was 7mm were examined using a experiment factorial randomized complete block design. The considered white rice quality measures were percentage of whole rice, broken rice, degree of milling and performance index. According to the result, rotor speed had significant effect on whole white rice and broken rice in level of 5%. Blade position and the interaction of rotor speed and blade position had significant effect on degree of milling and performance index at level of 1% and 5% respectively. Based on the results, the optimum operating conditions were 600 r.p.m and  distance blade from entrance side of rotor was 9mm and from exit side was 7mm. The rotor speed of 800r.p.m leads to same result.