The main reason for the massive loss of rapeseed in mechanized harvesting is the mismatch between the harvester requirements and the pod shatter resistance and plant branching characteristics. Low pod resistance, entanglement caused by excessive branches, and inconsistent pod maturity are primary mismatch problems. However, studies on rape characteristics by integrating agricultural machinery and agronomy are limited. A total of 15 varieties were planted for research from 2016 to 2018. In this paper, the Two-Degree-of-Freedom (2-DOF) collision method was adopted to evaluate the pod shatter resistance taken from the field, and the plant agronomic characteristics and their correlation were investigated. In 2020, a screened variety of C6009 with higher shatter resistance and suitable plant features for mechanized harvesting was planted in large areas and harvested by machines for verification. The test results demonstrated that the compact plant varieties with high branches might be more favorable for yield and shatter resistance. The field harvest loss of the screened variety was significantly less than that of the control group. It provides a reliable reference for agronomic experts in terms of rape variety improvement and agricultural machinery experts regarding the optimization of rape harvesters.

In order to solve the current problems of time-consuming manual work and low harvesting efficiency during the harvesting of potato breeding trials and the inability of traditional harvesting machinery to meet the requirements of potato single plant harvesting, a single plant harvester for potato breeding with a combined excavation device and a conveying and separating device with alternating concave and straight units is designed. This paper analyzes the force, motion, and collision of potato plants in the digging transition stage and conveying and separating stage. The key factors affecting the rate of single plant integrity and the rate of injured potatoes are determined. A three-factor quadratic regression orthogonal rotating combination experiment is conducted with the rate of single plant integrity and the rate of injured potatoes as experiment indexes, forward speed, conveying speed to forward speed ratio, and the rotational speed of the rear-vibration device as influencing factors. Based on the experiment results, a mathematical regression model is established, and response surface analysis and parametric analysis are conducted to determine that when the forward speed is 0.65 m∙s⁻¹, the ratio of conveying speed to forward speed is 0.98, and the speed of the post-vibration device is 11.52 rad∙s⁻¹, the single plant integrity rate is 97.14% and the rate of injured potatoes is 0.67%. The machine can better meet the requirements of potato single plant harvesting and solve the problem of plant mixing. From the perspective of potato damage rate, potato breeding harvesters are also suitable for traditional potato harvesting.

In this paper, a low-damage flexible drum-shaped threshing element is designed to address the stringent requirements for seed harvesting, specifically targeting the issues of high seed breakage rates, low threshing rates, and elevated entrainment loss rates during the mechanized harvesting process of rice seed propagation. Initially, a mathematical model was developed to determine the maximum normal impact force exerted by the threshing elements on rice seeds throughout the threshing process, derived from a comprehensive mechanical analysis. Subsequently, experimental research was conducted to investigate the physical properties of rice, leading to the establishment of a flexible, multi-level hollow stem discrete element rice model. This model facilitated an examination of the normal and tangential threshing forces from a microscopic perspective, thereby validating the performance of the flexible drum-shaped threshing element. Optimization simulation tests were then performed, with drum speed, feeding amount, and threshing gap serving as test factors, while the crushing rate and loss rate were used as test indexes. The results indicate that, under the optimal structural parameters of the threshing element, the ideal configuration includes a drum speed of 900 rmp, a feeding amount of 3.734 kg/s, and a threshing gap of 23.214 mm, resulting in a normal force of 18.05 N and a tangential force of 12.96 N, with a loss rate of 0.929%. Finally, a field harvest verification test was conducted based on these optimization results. Under identical working parameters, the breakage rate of the newly designed flexible threshing element was reduced by 55.9% compared to the traditional steel nail teeth, while the loss rate decreased by 15.3%, thereby fulfilling the high-quality harvesting requirements for rice seeds.

To address seed contamination, narrow-row mechanized cutting difficulties, and potential damage to maternal plants in muddy paddy fields during hybrid rice seed production, a walk-behind self-propelled hybrid rice male parent pulverizing and cutting machine was designed. The machine primarily consists of three key structures: a key cutting device, a gravity-free crop dividing device, and a crawler walking mechanism. The cutting device features an innovative mechanism where main-shaft rotation drives flail blades into inertial autorotation, while a stopper bar physically constrains their maximum swing amplitude to guarantee a 500 mm working width. Crucially, the gravity-free crop dividing device safely pushes aside adjacent maternal plants to effectively prevent accidental mechanical injury. A flexible plant model and a kinematic model were established using DEM software EDEM. A three-factor, three-level orthogonal experiment indicated the primary order of influence on the male parent cutting rate is: forward speed > flail blade rotational speed > blade arrangement. The optimal simulation parameters were a 0.4 m/s forward speed, a 1700 r/min blade rotational speed, and a straight-curved blade arrangement, yielding a simulated cutting rate of 97.60%. Furthermore, field tests demonstrated that under these optimal parameters, influenced by complex paddy conditions and natural plant lodging, the actual average cutting rate was 91.39%. The machine exhibited excellent passability and pulverizing performance, thoroughly satisfying the requirements of agronomic and agricultural machinery integration.

To address seed contamination, narrow-row mechanized cutting difficulties, and potential damage to maternal plants in muddy paddy fields during hybrid rice seed production, a walk-behind self-propelled hybrid rice male parent pulverizing and cutting machine was designed. The machine primarily consists of three key structures: a key cutting device, a gravity-free crop dividing device, and a crawler walking mechanism. The cutting device features an innovative mechanism where main-shaft rotation drives flail blades into inertial autorotation, while a stopper bar physically constrains their maximum swing amplitude to guarantee a 500 mm working width. Crucially, the gravity-free crop dividing device safely pushes aside adjacent maternal plants to effectively prevent accidental mechanical injury. A flexible plant model and a kinematic model were established using DEM software EDEM 2024. A three-factor, three-level orthogonal experiment indicated that the primary order of influence on the male parent cutting rate is forward speed > flail-blade rotational speed > blade arrangement. The optimal simulation parameters were a 0.4 m/s forward speed, a 1700 r/min blade rotational speed, and a straight–curved blade arrangement, yielding a simulated cutting rate of 97.60%. Furthermore, field tests demonstrated that under these optimal parameters, influenced by complex paddy conditions and natural plant lodging, the actual average cutting rate was 91.39%. The machine exhibited excellent passability and pulverizing performance, thoroughly satisfying the requirements of agronomic and agricultural machinery integration.