Journal of Agricultural Science and Technology
Volume:11 Issue: 3, Jul 2009

The population density and spatial distribution pattern of Empoasca decipiens Paoli were determined in Tehran area, Iran, during 2004-2005 on four species of common bean Phaseolus vulgaris (L.) var. Talash, lima bean P. lunatus (L.) Savi ex Hassk. var. Sadaf, rice bean P. calcaratus Roxb. var. Goli and cowpea Vigna sinensis (L.) var. Parastoo. The higher and lower mean population densities of E. decipiens per leaf were observed on Parastoo cowpea (18.85 in 2004 and 29.94 in 2005) and Talash common bean (1.08 in 2004 and 0.37 in 2005), respectively. Spatial distribution pattern of E. decipiens was described on these four bean species using variance to mean ratios, Taylor''s power law coefficients and Iwao''s patchiness regression methods. The spatial distribution pattern of this pest in most cases was aggregated and in a few cases random. In 2004, collected data were in a better fitting with Taylor''s model in comparison with Iwao''s model on Talash common beans (r2= 0.879) as well as on Goli rice bean (r2= 0.967). Iwao''s model explained the distribution data of 2004 and 2005 on Sadaf lima beans (r2= 0.746 and 0.906, respectively) more appropriately than Taylor''s model (r2= 0.541 and 0.828, respectively). It is concluded that bean species influence the population density and spatial distribution pattern of E. decipiens. Spatial distribution parameters can be employed to develop a sampling program and to estimate the population density of this pest.

In this study, an electrostatic sprayer which had been previously designed and constructed was evaluated in order to quantify the charging of droplets. Liquid atomization was achieved by using an ultrasonic nozzle. The nozzle maximum flow rate was 25 milliliters per minute and vibration frequency was about 30 kHz. The induction method was used for charging the output droplets. All experiments were carried out within a closed environment with a fixed ambient humidity and temperature to reduce the effect of environmental factors. The independent parameters in this study included: voltage at four levels of 1.5, 3, 5 and 7 kV; air flow speed at six levels of 14, 14.9, 17, 20.2, 21.6 and 23 m s-1; charging electrode radius in two levels of 10 and 15 millimeters, horizontal distance between the electrode and nozzle tip at four levels of 1.5, 6, 10 and 15 millimeters; and liquid flow rate at three levels of 5, 12 and 25 milliliters per minutes. For evaluation of the system, the charging quantities of droplets were measured in different states. The maximum charging occurred at 5 ml min-1 flow rate, voltage of 7 kV, air flow speed of 23 m s-1 and the resulting current was 0.24 µA. On dividing the electrical current by the liquid flow rate and changing the scale, the mean charge to mass ratio was 1.032 µC g-1. Increasing voltage increased the charging quantity slightly but higher voltages and lower air speeds decreased it. The effect of the faster air speed on droplet charging phenomena is positive and the smaller electrode radius causes less charge induction on the droplets. The quantity of droplets charging first increased with increased distance between ring electrode and nozzle tip, and then it was either reduced and/or fixed.

A project was established to develop a procedure for the selection, design, installation, test and evaluation of mass-flow rate measurement systems for root crop harvesting and to assess the consistency and precision of the weighing systems incorporated into crop feed arrangements in both laboratory and field studies. Studies were conducted to evaluate conveyor belt weighing systems using an experimental apparatus and a commercial potato harvester. Two weighing systems were evaluated: (a) cantilever transducers fitted to the conveyor belt mechanism and (b) a load cell system supporting the total weight of the conveyor and crop. The results of laboratory studies with sugar beet/potatoes showed that the standard cantilever transducers gave the smallest percentage of standard deviation from the mean experimental error ranging from 1.43 kg (connected to one idler roller) to 2.61 kg (connected to three idler rollers) with an appropriate value equal to 0.54 kg (connected to two idler rollers). The load cell supporting system also gave the smallest percentage of standard deviation from the mean experimental error ranging from 1.56 kg (continuous side feeding) to 2.25 kg (side feeding from right side) with an appropriate value equal to 0.84 kg (steady state side feeding). Experiments were conducted in the laboratory and field to assess the effects of belt inclination and extraneous vibration, transferred from the tractor to the harvester, on the measurements of crop mass. The results of field studies with potatoes using the cantilever transducers showed that the most precise system performance was obtained when using the 125 mm idler wheels with standard deviation of the mean experimental error of the sample yield equal to 0.99 kg. The results of barn studies with potatoes using the load cell supporting system showed that there was a good linear relationship between the measured and weighed mass of the potato samples with standard deviation of the mean experimental error equal to 0.34 kg.

A project was established to develop a procedure for the selection, design, installation, test and evaluation of mass-flow rate measurement systems for root crop harvesting and to assess the consistency and precision of the weighing systems incorporated into crop feed arrangements in both laboratory and field studies. Studies were conducted to evaluate conveyor belt weighing systems using an experimental apparatus and a commercial potato harvester. Two weighing systems were evaluated: (a) cantilever transducers fitted to the conveyor belt mechanism and (b) a load cell system supporting the total weight of the conveyor and crop. The results of laboratory studies with sugar beet/potatoes showed that the standard cantilever transducers gave the smallest percentage of standard deviation from the mean experimental error ranging from 1.43 kg (connected to one idler roller) to 2.61 kg (connected to three idler rollers) with an appropriate value equal to 0.54 kg (connected to two idler rollers). The load cell supporting system also gave the smallest percentage of standard deviation from the mean experimental error ranging from 1.56 kg (continuous side feeding) to 2.25 kg (side feeding from right side) with an appropriate value equal to 0.84 kg (steady state side feeding). Experiments were conducted in the laboratory and field to assess the effects of belt inclination and extraneous vibration, transferred from the tractor to the harvester, on the measurements of crop mass. The results of field studies with potatoes using the cantilever transducers showed that the most precise system performance was obtained when using the 125 mm idler wheels with standard deviation of the mean experimental error of the sample yield equal to 0.99 kg. The results of barn studies with potatoes using the load cell supporting system showed that there was a good linear relationship between the measured and weighed mass of the potato samples with standard deviation of the mean experimental error equal to 0.34 kg.

This paper peresents a mathematical model for the thin layer drying of the Viliamz cultivar of soybean. The thin layer drying behaviour of soybean was experimentally investigated and the mathematical modelling performed by using thin layer drying models provided in the literature. Experiments were conducted at inlet drying air temperatures of 30, 40, 50, 60 and 70ºC and at a fixed drying air velocity of 1 m s-1. Thirteen different thin layer mathematical drying models were compared according to their r values, RMSE, c2 and EF by non-linear regression analysis. The effect of drying air temperature on the model constants and coefficients was predicted using multiple regression analysis. According to the results, the Midilli et al. model was found to be the best mathematical equation for modelling thin layer drying of soybean.

Proper conditions for producing crude beta-galactosidase from waste materials were determined. This enzyme is to be used in the production of lactose-hydrolyzed milk. Whey permeate was used as a basic medium. Twenty seven treatments were developed by 3 varying factors of: yeast extract (1, 2, and 3 %), wheat steep liquor (1, 2, and 3 %), and whey powder (0.5, 1, and 1.5 %). Crude enzyme extract was obtained by sonication of the cells collected from cultivation of Lactobacillus delbrueckii ssp. bulgaricus in various media at 43oC. The beta-galactosidase activity was assessed using Ortho-Nitro-Phenyl-beta-D-galactopyranoside (ONPG). Yeast extract and whey powder had both significant effects (P< 0.01), while wheat steep liquor proved to be ineffective. Yeast extract had the most pronounced effect on the production of beta-galactosidase. The effect of the interactions of yeast extract-whey powder and wheat steep liquor-whey powder were significant at 5 % level (P< 0.05), while the effect of the interaction of yeast extract-wheat steep liquor was significant at 1% level (P< 0.01). Interaction effect of the 3 factors on the production of beta-galactosidae was significant (P< 0.01). The best combination for production of beta-galactosidase (4.924 U ml-1) was 3% yeast extract, 1.5% whey powder and 2% wheat steep liquor.

Physical properties of four common Iranian varieties of canola seeds (Hyola, Okapi, Orient and SLM) were evaluated as a function of their moisture contents. The average seed length and thousand seed mass varied linearly from 1.925 to 2.262 mm and from 3.06 to 4.84 g, respectively. The average diameter, geometric mean diameter, and sphericity varied non-linearly from 1.475 to 1.911 mm, 1.625 to 2.02 mm and from 0.82 to 0.93, respectively in a moisture content range of 5.27 to 23.69% wet basis (w.b.). Among the varieties, Hyola had the highest values for length, diameter, geometric mean diameter, sphericity and thousand seed mass at all moisture levels. Maximum and minimum values of bulk density were obtained for SLM (738.8 kg m-3) and Hyola (666.06 kg m-3). The filling and emptying angles of repose ranges were determined as 25.37-28.54o and 25.48-28.68o, respectively. At all moisture content levels, the static coefficient of friction was the greatest against rubber (0.372-0.460), followed by plywood (0.358–0.449), galvanized iron sheet (0.301–0.419) while fiberglass sheet (0.260-0.414) while the least for glass sheet (0.253–0.392). Among the four canola varieties, Orient and SLM showed respectively the least and the greatest static coefficients of friction at all moisture levels studied.

There are more than 37,000 hectares of land cultivated with date palm in Hormozgan Province producing around 145,000 tons of date annually. Therefore, increasing date yield and quality can render positive effects, especially on farmers, income in the region. One of the most important agricultural practices is mineral nutrition and soil fertility management that can improve yield and fruit quality of date palm. This research was conducted for a duration of three years to study the effect of essential nutrients application on Date Bunch Wilt and Dry disordr (DBWD) which has caused large production reductions in recent years. Two palm groves of “Mordasang” cultivar were chosen as experimental sites. One was afflicted with DBWD and the other one healthy. Fertilizer treatments were applied on the basis of soil and leaf analysis as follows: 1-Control (with no use of fertilizers) 2- Addition of balanced amounts of macro-nutrients and 3-Addition of balanced amounts of macro as well as micro-nutrients. The experiment was arranged with a complete randomized block design of five replications. Maintenance operations consisted of pollination, weeding, disease and pest control. Such plant responses as fruit yield, bunch number and percentage of bunches afflicted by DBWD were determined and compared among treatments. There was no significant difference observed between bunch numbers per tree in the fertilizer treatments. Application of essential nutrient elements (treatments 2 and 3) resulted in a considerable increase in date yield and a decrease in dried bunches percentage.

Reservoir dams are among the main storage systems employed in agriculture for the several past decades. Proper operation of these reservoirs is important for irrigation especially in such arid and semi-arid areas like Iran, and particularly during dry years. A computational framework for reservoir simulation and flood routing is hereby presented. A key aspect of the reservoir simulation is the ease of use by managers and model users. In this paper, an object-oriented toolkit for building computer models for simulation of reservoir operation and flood routing in Boukan reservoir dam is used. The modeling approach taken in this paper is significantly different from that typically employed in the development of water resources planning and management models. The medium in this kind of model provides a graphical object-oriented interface that allows the user(s) to model complex systems without even requiring a profound proficiency in computer programming. The Object Oriented Programming (OOP) environment chosen to develop the model of Boukan dam reservoir was STELLA Software. The probability of flood occurenceis also taken into account for a prediction of more accurate results.

Investigation of the interrelationships between yield and its components will improve the efficiency of a breeding program with appropriate selection criteria. In this study, the relationship among yield components and their direct and indirect influences on the total yield of melon were investigated. The study was based on evaluation of 49 entries generated from a 7×7 diallel involving Iranian melon landraces under two conditions of cultivation, pruning and non-pruning. A sequential path model was used for ordering the various variables in first and second-order paths based on their maximum direct effect and minimal colinearity. Two first-order variables, namely the number of fruits per plant and average weight of fruits per plant accounted for 91% and 83% of total variation in total weight per plant under the pruning and non-pruning conditions, respectively. The direct effects of these two variables on total weight per plant under non-pruning conditions were nearly equal, but the direct effect of average weight of fruits per plant in the pruning data set was much higher than the number of fruits per plant (1.14 vs. 0.73). All direct effects were found to be significant as indicated by bootstrap analysis. The results indicated the utility of the sequential path model for determining the interrelationships between yield and related traits in melon.

Runoff estimation is one of the main challenges encountered in water and watershed management. Spatial and temporal changes of factors which influence runoff due to heterogeneity of the basins explain the complicacy of relations. Artificial Neural Network (ANN) is one of the intelligence techniques which is flexible and doesn’t call for any much physically complex processes. These networks can recognize the relation between input and output. In this study ANN model was employed for runoff estimation in Plaszjan River basin in the central part of Iran. The models used are Multiple Perceptron (MLP) and Recurrent Neural Network (RNN). Inputs include data obtained from 5 rain gauges as well as from 2 temperature recording gauges, the output of the model being the monthly flow in Eskandari Hydrometric Station. Preprocessing of the data as well as the sensitivity analysis of the model were carried out. Different topologies of Neural Networks were created with change in input layers, nodes as well as in the hidden layer. The best architecture was found as 7.4.1. Recurrent Neural Network led to better results than Multilayer Perceptron Network. Also results indicated that ANN is an appropriate technique for monthly runoff estimation in the selected basin with these networks being also of the capability to show basin response to rainfall events.

The present study was carried out in Kharkeh Research Station, Kurdestan Province, western Iran to investigate the effects of the change in land use on the degradation of Mollisols, their organic carbon content, clay mineralogy and K+ status. The study area was partly under cultivation (for over 40 years) and partly preserved as rangelands. The results revealed that Mollisols are the dominant soils in non-cultivated natural rangelands. The adjacent cultivated soils, however, lack enough organic carbon to meet the requirements of Mollisols. Cultivation practices had exerted adverse effects on some such major soil properties as organic carbon, cation exchange capacity, as well as macro- and microstructure. Clay minerals and different forms of potassium did not show significant differences in the two land uses. Parent material rich in such potassium bearing minerals as feldspars and mica, as well as the dominance of illite in soils, were probably the main factors responsible for adjustment of the soil K+, rendering the changes relatively non-significant.