The cutting device in the seedling grafting process was studied, which provided a reference for optimizing the structural parameters and working parameters of important shearing components in the seedling grafting line, thereby improving the performance of the cutting device. The dynamic cutting process of the cutting device was numerically simulated. The effects of four factors, the average cutting speed (X₁), the sliding angle (X₂), the cutting edge angle (X₃), and the cutter clearance (X₄) on the cutting force, were studied. The optimal combination of structural parameters and working parameters of the cutting device was determined. The simulation results showed that the sliding angle (X₂) and the cutting edge angle (X₃) affect the ultimate cutting stress. The average cutting speed (X₁) and the cutter clearance (X₄) affect the ultimate cutting force. When X₁, X₂, X_3, and X₄ are 579 mm/s, 39°, 25°, and 1.4 mm, respectively, it is the better combination parameter, and the ultimate cutting equivalent stress of the cutting device is 0.32 Mpa. A high-speed cutting device for grafted seedlings was built, and the cutting experiment was carried out. The experiment results showed that the simulated values fit well with the experimental data. Under the optimal combination of cutting parameters, the cutting stress of the cutting device was smaller. The finite element simulation of the seedling grafting cutting device reduces the experiment cost and provides a reference for developing the seedling grafting line.

To address the issues of low efficiency, high cost of manual harvesting, and the lack of mechanized harvesting technology and equipment for high-stem Chrysanthemum coronarium, a self-propelled orderly harvester was designed to perform key harvesting operations such as row alignment, clamping and cutting, orderly conveying, and collection. Based on the analysis of agronomic requirements for cultivation and mechanized harvesting needs, the overall structure and working principle of the machine were described. Meanwhile, the key components such as the reciprocating cutting mechanism and orderly conveying mechanism were structurally designed and theoretically analyzed. The main structural and operating parameters of the harvester were determined based on the geometric and kinematic conditions of high-stem Chrysanthemum coronarium during its movement along the conveying path, as well as the mechanical model of the conveying process. In addition, a three-factor, three-level Box-Behnken field experiment was also conducted with the experimental factors including the machine’s forward, cutting, and conveying speed, and evaluation indicators like harvesting loss rate and orderliness. A second-order polynomial regression model was established to analyze the relationship between the evaluation indicators and the factors using the Design-Expert 13 software, which revealed the influence patterns of the machine’s forward speed, reciprocating cutter cutting speed, conveying device speed, and their interaction influence on the evaluation indicators. Moreover, the optimal parameter combination, obtained by solving the optimization model for harvesting loss rate and orderliness, was forward speed of 260 mm/s, cutting speed of 250 mm/s, and conveying speed of 300 mm/s. Field test results showed that the average harvesting loss rate of the prototype was 4.45% and the orderliness was 92.57%, with a relative error of less than 5% compared to the predicted values. The key components of the harvester operated stably, and the machine was capable of performing cutting, orderly conveying, and collection in a single pass. All performance indicators met the mechanized orderly harvesting requirements of high-stem Chrysanthemum coronarium.

In order to yield a marketable product, hand fruit thinning (HFT) has become the major but costly management practice in modern pear planting. Two kinds of new blossom thinners for pear blossom thinning were developed, which are tractor-mounted three arms blossom thinner (TTBT) and hand-held electric blossom thinner (HEBT). Four treatments for 24 trunk type ‘Cuiguan’ pear trees (7 years) were tested. They are TTBT combined with HFT, HEBT combined with HFT, hand blossom thinning (HBT) combined with HFT, and HFT only. Pear trees were divided into 4 groups equally. Four indexes were used to evaluate the test: flower reserve rate, fruit set rate, work efficiency and cost, fruit yield, and quality. Pear canopy was divided into the inner, middle, and outer 3 layers in the top view. 20 inflorescence samples were selected for each layer. Field tests showed: there was no obvious difference in quality between mechanical blossom thinning and HBT, and the working stability of TTBT was higher than other treatments. Mechanical blossom thinning decreased the fruit set rate to a certain degree, but did not reduce the yield and quality of harvesting. TTBT could save 61.35% operation time compared with HFT, and the profitable area was 5845.76 m2. TTBT is suitable for large-scale sparse layer trunk-type pear orchards. HEBT could save 36.01% operation time compared with HFT, and the profitable area was 663.96 m2. HEBT is suitable for small and medium-sized trunk-type pear orchards. Blossom thinning can improve the average weight of high quality fruit and brix of sugar solids. Keywords: mechanical blossom thinning, pear orchard, trunk type, performance evaluation DOI: 10.25165/j.ijabe.20211404.6060 Citation: Lei X H, Lyu X L, Zhang M N, Lu D P, Wang S L, Chang Y H, et al. Performance evaluation of mechanical blossom thinning in trunk type pear orchard. Int J Agric & Biol Eng, 2021; 14(4): 106–112.

There is a close relationship between stem and leaf biological characteristics of mature broccoli plants and defoliation technology. Morphological parameters such as the spread degree and diameter of cauliflower stem and leaf and the connection performance of cauliflower stem and leaf were studied. These experiments are helpful to the research of defoliation devices and methods for large-scale manual transportation lines. In this paper, according to the damage forms that may be suffered in the separation process of mature broccoli stems and leaves, “sunny” broccoli varieties were selected. Firstly, the mechanical properties of mature broccoli stems were obtained through different loading methods such as stretching, compression, shearing and bending. Secondly, the stress relaxation characteristics of broccoli were analyzed by static compression of broccoli flower balls. Finally, the separation method of broccoli stems and leaves was simulated by ANSYS. The simulation results showed that shear fracture was more suitable for stem and leaf separation of broccoli than tensile fracture. Then, aiming at the separation of stems and leaves of broccoli, an artificial broccoli assembly line was proposed to ensure the efficiency of leaf removal through man–machine cooperation. The dynamic characteristics of the belt of broccoli leaf removal line were studied to ensure the efficient and stable operation of the conveyor system of broccoli artificial leaf removal line.

Design of a fixed-pipe cold aerosol spraying system for chemical application in greenhouse

Accurate canopy thickness measurement is vital for advancing smart orchard sprayers and reducing pesticide use. We present three FMCW radar-based algorithms to estimate canopy thickness and assess their accuracy through experiments. Laboratory tests on simulated canopies showed a strong correlation between estimated and actual thickness. However, stability and relative error were significantly affected by leaf area density (LAD) and detection distance. When distance was 40.0–110.0 cm, LAD 1.5–4.2 m²/m³, and actual thickness 30.0–120.0 cm, the coefficient of variation and relative error remained within ±14%. Preliminary outdoor trials on three isolated tree canopies served strictly as an early proof-of-concept, not a full orchard evaluation. The Db algorithm performed poorly, with relative error up to 74.9%, whereas the Da and Dc methods proved robust, with maximum relative errors of 11.93% and −15.19%, respectively. These findings highlight that, with further refinement, Da and Dc algorithms are highly promising for precision variable-rate spraying systems in orchards.