To address the challenges of manually excavating deep-rooted medicinal herbs in the cold and arid regions of northwest China, such as low efficiency, high costs, and difficulties with mechanized methods, a self-propelled fork-tooth digger was developed for use in hilly and mountainous terrains. Key components, including the fork-tooth excavation device, hydraulic control system, and reverse trapezoidal crawler chassis, were designed and analyzed. A multi-body dynamics model (MBD) and discrete element model (DEM) for Astragalus and soil were developed, employing a DEM-MBD coupling method to simulate the harvesting process. Field trials demonstrated an excavation efficiency of 98.2%, a stem damage rate of 1.8%, a loss rate of 3.0%, and a maximum digging depth of 600 mm, all meeting existing industry standards. The results confirmed the design's effectiveness in meeting the mechanization needs for harvesting rhizome medicinal herbs.

In China's Yangtze River and Yellow River basin cotton-growing regions, the complex terrain, scattered planting areas, and poor adaptability of the existing machinery have led to a mechanized cotton harvesting rate of less than 10%. To address this issue, we designed a crawler chassis for a brush-roller cotton harvester. It is specifically tailored to meet the 76 cm row spacing agronomic requirement. We also conducted a theoretical analysis of the power transmission system for the crawler chassis. Initially, we considered the terrain characteristics of China's inland cotton-growing regions and the current cotton agronomy practices. Based on these, we selected and designed the power system and chassis; then, a finite element static analysis was carried out on the chassis frame to ensure safety during operation; finally, field tests on the harvester's operability, stability, and speed were carried out. The results show that the inverted trapezoidal crawler walking device, combined with a hydraulic continuously variable transmission and rear-drive design, enhances the crawler's passability. The crawler parameters included a ground contact length of 1650 mm, a maximum ground clearance of 270 mm, a maximum operating speed of 6.1 km/h, and an actual turning radius of 2300 mm. The maximum deformation of the frame was 2.198 mm, the deformation of the walking chassis was 1.0716 mm, the maximum equivalent stress was 216.96 MPa, and the average equivalent stress of the entire frame was 5.6356 MPa, which complies with the physical properties of the selected material, Q235. The designed cotton harvester crawler chassis features stable straight-line and steering performance. The vehicle's speed can be adjusted based on the complexity of the terrain, with timely steering responses, minimal compaction on cotton, and reduced soil damage, meeting the requirements for mechanized harvesting in China's inland small plots.

In Tigray, northern Ethiopia, prickly pear (Opuntia ficus-indica) is an important crop that serves as a source of seasonal food and income, soil and water conservation, live fencing, and an all-year-round livestock feed. With the intention of increasing the benefits from the crop, an exotic insect, the cochineal (Dactylopius coccus), was intentionally introduced. Nevertheless, the insect has gone wild and caused severe damage to the crop. It has now become a serious threat to the survival of the plant species in the Tigray region. Thus, cactus pear populations and exotic materials were evaluated in the laboratory for their resistance to the insect. The cultivars were tested in 2018 using a complete randomized experimental design with five replications and several plants from three different species of cactus pear: (Opuntia ficus-indica, Opuntia stricta, and Opuntia robusta). Each cladode of the test entries was artificially inoculated with 30 crawlers (mobile first instar) of Dactylopius coccus, less than 24 hours from hatching. Days to first and second molting, days to maturity and number of surviving crawlers on each infested cladode after 7, 14, 21 and 45 days were recorded. The number of crawlers in susceptible species, the weight, size and the relationship between weight and size of insects to the number of crawlers produced were also recorded. There was a highly significant difference among cactus pear species in their resistance to the insect, expressed in terms of the number of surviving crawlers and days to maturity. None of the cochineal crawlers on O. stricta and O. robusta test cultivars were able to reach maturity. On the other hand, most of the cochineal crawlers inoculated on the O. ficusindica lines were able to reach maturity and produce new offspring. The average period for first instar, second instar, maturity and life cycle of the female cochineal, was 19.4, 15.2, 40.4 and 75 days respectively. Thus, both O. robusta and O. stricta were resistant while all O. ficus-indica lines tested were completely susceptible. Besides, the number of crawlers produced per mature female cochineal was found to have a significant correlation coefficient with the size and weight of individual female cochineal. In areas where O. ficus-indica is challenged by D. coccus, suitable cultivars of O. stricta and O. robusta could perhaps perform the same services that were previously filled by O. ficus-indica.