The labor shortage and rising costs in the greenhouse industry have driven the development of automation, with the core of autonomous operations being positioning and navigation technology. However, precise positioning in complex greenhouse environments and narrow aisles poses challenges to localization technologies. This study proposes a multi-sensor fusion positioning and navigation robot based on ultra-wideband (UWB), an inertial measurement unit (IMU), odometry (ODOM), and a laser rangefinder (RF). The system introduces a confidence optimization algorithm based on weakening non-line-of-sight (NLOS) for UWB positioning, obtaining calibrated UWB positioning results, which are then used as a baseline to correct the positioning errors generated by the IMU and ODOM. The extended Kalman filter (EKF) algorithm is employed to fuse multi-sensor data. To validate the feasibility of the system, experiments were conducted in a Chinese solar greenhouse. The results show that the proposed NLOS confidence optimization algorithm significantly improves UWB positioning accuracy by 60.05%. At a speed of 0.1 m/s, the root mean square error (RMSE) for lateral deviation is 0.038 m and for course deviation is 4.030°. This study provides a new approach for greenhouse positioning and navigation technology, achieving precise positioning and navigation in complex commercial greenhouse environments and narrow aisles, thereby laying a foundation for the intelligent development of greenhouses.

This research combined micro/nano bubble techniques with ozone disinfection to determine feasibility of applying micro/nano bubble ozonated water in preventing tomato airborne disease. Results indicated that dissolving ozone in micro/nano bubbles is more efficient than using a mixing pump. In our in vitro studies, when dissolved ozone concentration was 1.6 mg/L, a 5.2 to 3.3 log reduction in Alternaria solani Sorauer conidia was observed; with concentration of 1.8 mg/L, there was a 5.0 to 3.7 log reduction in Cladosporium fulvum conidia. Furthermore, spraying ozonated water in a certain concentration range (0.6–1.8 mg/L) had no significant negative effects on tomato growth.

As a promising environmental protection technology, the application of ultraviolet B irradiation in vegetable production has been widely considered. However, the effect of UVB irradiation varies with different plant varieties. In this study, we investigated the effects of two UVB intensities (0.7, 1.4 W m⁻²) on the accumulation of phenolics and flavonoids, and antioxidant activity of green-leaf and red-leaf lettuce (Lactuca sativa L.) 7 days prior to harvest. The results indicated that short-term (within 2 days) UVB treatment could promote the increase in total chlorophyll content of red-leaf lettuce and green-leaf lettuce, which increased by 49.8% and 20.6% compared with day zero, respectively, and was beneficial to the synthesis of carotenoids of red-leaf lettuce. Extending UVB exposure time significantly decreased chlorophyll a/b value of green-leaf lettuce from 0.92 to 0.63, and simultaneously increased the accumulation of antioxidant substances such as flavonoids, which were increased by 90.0% and 183.4% compared with day zero for UVB-0.7 and UVB-1.4 treatments of red-leaf lettuce, 84.1% and 110.9% of green-leaf lettuce. In contrast, red-leaf lettuce had a higher accumulation level of secondary metabolites, faster scavenging rate of free radicals, and stronger ability to resist UVB stress. Our results suggest that supplementation of low-dose UVB radiance prior to harvest can improve the secondary metabolite content and antioxidant activity of the two kinds of lettuce. This research provided a theoretical basis for improving lettuce quality by pre-harvest UVB treatment in controlled environmental agriculture.

Transplanting is a critical step in vegetable production, and the application of automatic transplanters can significantly reduce labor intensity, improve production efficiency, and enhance the precision and consistency of operations. However, automatic transplanters are structurally complex, with diverse components, each design and function offering its own advantages and limitations. To assist industry professionals in quickly understanding and selecting transplanters suited to specific crops and environments, this paper reviews three key technologies in current vegetable transplanters: planting mechanisms, automated seedling picking and placing, and tray conveyance. Each technology is classified, compared, and analyzed to evaluate its applicability. Based on the current state of technology, the paper identifies major challenges in the development of vegetable transplanters in China, including insufficient integration of machinery and agronomy, high demands for equipment adaptability, lack of standardized systems, and delays in the development of core technologies for fully automated transplanting. Solutions are proposed for each of these issues. Finally, the paper discusses future directions for the development of automatic transplanters, including enhancing transplanting efficiency, achieving autonomous navigation, digitalizing operations, developing supporting systems for transplanting, and unmanned transplanting.

Root-zone temperature (RZT) is an indispensable environmental factor for the proper growth and development of plants. Low RZT is one of the major limitations for agricultural production during cold seasons. In this study, the physiological responses of tomato seedlings to low RZT stress (10 °C) and its recovery were investigated with hydroponic cultivation in an artificial climate-controlled chamber. The stress reaction of tomato seedlings was evaluated by combining various indexes, including photosynthesis, chlorophyll fluorescence, root activity, hydrogen peroxide, and antioxidants. The results showed that low RZT adversely affected root activity, and in response to the limited root-source water and mineral elements, supply for shoot metabolism, leaf photosynthesis, and chlorophyll fluorescence were negatively influenced, which led to inhibited leaf area development and biomass accumulation. Hydrogen peroxide (H ₂ O ₂ ), malondialdehyde (MDA), and proline accumulated with the time of low RZT stress. When restored to normal temperature (∼20 °C), the physiological parameters recovered to a certain degree, although most parameters were not at a similar level with the control. In crop production during cold seasons, it is necessary to improve the RZT to achieve high quality and yield production.

In this study, Dianthus caryophyllus L. was used as the experimental plant to investigate the effects of rooting substrate and exogenous auxin concentration on the adventitious rooting of the stem cuttings. Our results showed that the formulated substrates with different physicochemical properties significantly affected the root formation. The substrate with a ratio of cocopeat to perlite at 1:1 (v:v) resulted in the optimum rooting of D. caryophyllus cuttings. Different Indole-3-butyric acid (IBA) and 1-naphthalene acetic acid (NAA) concentrations affected the rooting percentage and seedling rate of D. caryophyllus . Application of NAA at 1000 mg·kg ⁻¹ with IBA at 100 mg·kg ⁻¹ resulted in the greatest rooting percentage and improved breeding speed. The rooting percentage and seedling rate did not increase with the increase in auxin concentration. Based on these results, we concluded that an appropriate rooting substrate is required to fulfill proper rooting of D. caryohhyllus cuttings, whereas an exogenous application of IBA and NAA at 1000 mg·kg ⁻¹ and 100 mg·kg ⁻¹ promoted the rooting and a higher auxin concertation inhibited rooting.