نشریه ماشین های کشاورزی
سال دهم شماره 1 (پیاپی 19، نیمسال اول 1399)

Non-chemical treatments are an approach for improving seed germination. In order to evaluate the effects of the magnetic field application on onion seed germination and seedling growth indices, a quadrupole magnetic field system was designed and fabricated. It was also compared with a dipole magnetic field system. In the quadrupole system, each coil consisted of three layers and the cores were moved inside the coils. These arrangements make it possible to change the magnetic field intensity in addition to input current setting. The experiments were conducted based on factors including the type of system (bipolar and quadrupole), magnetic flux density (75, 150, 300 and 600 μT) and duration of the field application (15, 30, 60 and 120 min). Germination percentage, germination rate, mean germination time, seedling vigor index, shoot length, root length, fresh weight of shoot and root, fresh weight of seedling, dry weight of shoot and root were measured. The results showed significant effects on seed germination and seedling growth of onion. In most germination characteristics, the quadrupole system had a better impact than the bipolar system. For many traits (except for weights), the increase in field intensity degraded the traits. Quadrupole system that applied the magnetic field of 600 μT for 15 minutes, yielded 63% increase in the total seedling weight. Most of the germination traits were not affected by exposure time. Further investigations are required for shorter exposure times compared to used durations in this study.

The aim of this study is to design, fabricate and evaluate a new type of up-cut rotary tiller and to develop correct formulas to estimate its torque and draft force using the laws of classical mechanics. In order to verify the model, a real-sized prototype of the rotary tiller was tested. It was hypothesized that four processes are involved to create the rotary tiller torque, namely soil cutting, soil lifting, soil-metal friction, and soil velocity. Furthermore, it was assumed that the horizontal components of soil cutting and soil-metal friction forces create the required draft of the machine. Based on these hypothesizes, mathematical formulas were developed to calculate torque, and draft requirements of the machine. To facilitate performing necessary calculations, the developed formulas were entered in a worksheet of the MS Excel software. According to the results of this study, the average experimental draft and torque of the machine tilling a silty clay loam soil were 16.8 N and 12.8 Nm, respectively. Furthermore, the average theoretical draft and torque of the machine were 13 N and 11.8 Nm respectively. These promising results can be considered as the accuracy check of the formulas developed herein.

In this paper, performance of a no-till corn planter in a soil covered with previous wheat residue was evaluated. Three levels of crop residue cover (CRC): 30, 45 and 60%, two planting schemes; on-bed and in-furrow and two forward speed: (4 and 8 km h-1) were considered as treatments. The field was evaluated by ground and air observations. The purpose of this study was to investigate the capability of aerial images captured by an unmanned aerial vehicle (UAV) in identifying the distances between corn seedlings and as a result, assessing the quality of planter performance. Collected data from ground and aerial imagery were used to calculate seed establishment indices including multiple index, miss index, quality of feed index, precision index and also emergence rate index (ERI), for each plot. Images captured from10 m altitude (4.5 mm pixel-1) could give satisfactory results in relation to our objectives. Our results show that acceptable correlations existed between terrestrial and aerial seedlings spacing data sets (0.94<R<0.98) suggesting the aerial imagery is a good choice for evaluating the seed establishment and estimating ERI. Aerial imagery data source underestimated quality of feed and precision indices, overestimated miss index and could not provide processed data range needed for computing multiple index due to low image resolution, weeds presence within crop rows and overlapping of leaves.

Fire Blight (FB) is the most destructive bacterial disease of pome fruit trees around the world. In recent years, spectrometry has been shown to be an accurate and real-time sensing technology for plant disease detection. So, the main objective of this research is early detecting FB of pear trees by using Visible-Near-infrared spectrometry. To get this goal, the reflectance spectra of healthy leaves (ND), non-symptomatic (NS), and symptomatic diseased leaves (SY) were captured in the visible–NIR spectral regions. In order to keep the important information of spectra and reduce the dimension of data, three linear and non-linear manifold-based learning techniques were applied such as, Principal Component Analysis (PCA), Sammon mapping and Multilayer auto-encoder (MAE). The output of manifold-based learning techniques was used as an input of the SIMCA (Soft independent modeling by class analogy) classification model to discriminate NS and ND leaves. Based on the results, the best classification accuracy obtained by using PCA on the 1st derivative spectra, with accuracy of 95.8%, 89.3%, and 91.6% for ND, NS, and SY samples, respectively. These results support the capability of manifold-based learning techniques for early detection of FB via spectrometry method.

The overall objective of this research is to check the abilities of two non-destructive techniques, the digital imaging (DI) and laser light backscattering imaging (LLBI), on detection of α-solanine toxicant in potatoes. Potato samples were classified in healthy and toxic categories based on the amount of α-solanine. For quantifying α-solanine in potato tubers, high-performance liquid chromatography (HPLC) has been used. The results of classification showed that single layer perceptron neural networks can classify potatoes with the accuracies of 94.28% and 98.66% by DI and LLBI systems (Donald cultivar), respectively. It can be said that LLBI systems might take precedent over DI systems due to their high accuracy, rapidity, and industrial capability.

The purpose of this study was to model and optimize the offline refinement operations of sugarcane harvester hydraulic oil using RSM. For this purpose, the effects of independent variables of operating hours (250, 500 and 750 hours), Twin Dip Filter Mesh (7, 9 and 11 microns) and hydraulic oil refining times (0, 1 and 2) on variables of water contamination, uncleanness level (NAS), silicon (Si), viscosity (Vis) and oil acid number (TAN) were evaluated. The results indicated that all models were suitable for water contamination, uncleanness level (NAS), silicon (Si), viscosity (Vis) and oil acid number (TAN) for describing experimental data. In addition, the desirability function showed that the optimum conditions for the offline refinement operations of the hydraulic oil of the sugar cane harvester included 728.61 operating hours, the 7-micron filter mesh, and the two refining times of the oil. Under this condition, the amount of water contamination, the uncleanness level (particles 5 to 15 micrometers), Vis, Si, and TAN were equal to 187.63 ppm, 234000, 5.91 ppm, 66.34 centistokes and 0.65 (mg KOH g-1), respectively.

Harvesting is one of the most important field operations in sunflower production. Seed damage and low separation efficiency are the top concerns of harvesting sunflower. In this study, a threshing cylinder with rubber teeth and a concave for harvesting sunflower were designed and evaluated. The variable parameters were threshing cylinder speed (TCS), threshing space (TS) and moisture content (MC) of sunflower head. Azargol variety was used to evaluate the threshing unit. The tests were performed at three cylinder speed levels (280, 380 and 480 rpm), two threshing spaces (8 and 10 cm) and two moisture content of sunflower head based on the crop condition (20% and 45% wet basis). An ANN model was developed to predict the amount of materials in each part of the concave. Results showed that the sunflower seeds had no damage during the threshing process and the presented model could predict the amount of materials in each part of the concave with a regression coefficient R2=0.95. Based on the ANN model, with a decrease in MC and TS, and an increase in TCS, the separation efficiency was increased. Furthermore, optimal parameters for the threshing unit which were suggested by Design Expert software to maximize the separation efficiency were 18% w.b, 450 rpm and 10.5 cm for MC, TSC, and TS, respectively and in this condition separation efficiency was determined to be 94.92%.

A robust numerical analysis was proposed for simulating the rebound velocity pendulum method for melon. For considered varieties (Zard-Eyvanekey and Sousky-Sabz varieties), the change in impact parameters (extracted from excitation by pendulum) was studied for five stages of ripening. With the melon ripeness, the rebound velocity, rebound height, relative rebound height, rebound angle, rebound energy and coefficient of restitution (velocity ratio) increased, while the absorbed energy decreased (from 37.6 to 27.9 MJ for Zard-Eyvanekey and from 38.5 to 27.9 MJ for Sousky-Sabz). The regression analysis showed a highly significant linear relationship (coefficient of determination, R² more than 0.8059) between impact parameters and five stages of ripening. So the results of the analysis are feasible in ripening detection and hence in the classification of the melon maturity.

The eggshell of birds, as a natural shield and package, protects the tissues inside it from microbial and mechanical damages. Proper intake of calcium, as an important and effective factor in increasing the strength and quality of the eggshell, could reduce complications. In this paper, the effect of dietary calcium at five different levels on engineering features of Japanese quail eggs in a in their first laying period was investigated. The values for an average of mass, volume, specific mass, shell thickness, major diameter, central diameter and rupture force along the longitudinal and transverse axes were measured. Rupture energy or toughness, slope of the rupture curve (hardness), deformation along the longitudinal and transverse axis to the point of rupture as well as longitudinal and transverse deformation of 450 tested quail eggs (3 period of time, 5 treatment of calcium, 5 replication, 6 observation) were measured. The characters of the specific mass, shell thickness, rupture force, and slope of the rupture curve of quail eggs indicate the strength of quail egg. In this study, variations in all parameters indicating shell strength at different levels of dietary calcium were consistent with each other. Five different treatments with 1.5%, 2%, 2.5%, 3%, and 3.5% calcium content were supplied for the study. By increasing the calcium content of the quail diet from 1.5 to 3 wt%, the volume and weight of quail eggs dropped and shell thickness was reinforced. According to the results, the shell strength of quail eggs along the transverse axis was slightly less than the longitudinal axis, but the flexibility and energy required for quail egg rupture were much greater across the longitudinal axis.

In this study, the effect of conservation tillage and irrigation methods on the soil properties, cotton yield, and water productivity was evaluated in a wheat-cotton cropping system in the form of a split-plot experimental design. The main plots were irrigation using the three methods including surface irrigation, drip tape irrigation, and sprinkler irrigation. Tillage methods including zero tillage, reduced tillage, and conventional tillage were considered as subplots in this research. Results showed that tillage methods had no significant effect on cotton yield; whereas, the cotton yield was significantly affected by irrigation methods (p˂0.05). Tape and sprinkler irrigation methods saved water compared to surface irrigation for 51% and 28%, respectively. The maximum water productivity (0.324 kg m-3) was obtained from the tape irrigation and the minimum water productivity (0.146 kg m-3) was related to surface irrigation. Results also indicated that irrigation and tillage methods had a significant effect on the soil bulk density and infiltration rate so that drip tape irrigation and conventional tillage had the highest infiltration rates, and tape irrigation and reduced tillage had the highest soil bulk density.