During the overwintering production of lettuce in solar greenhouses, there exist a short duration of sunlight and low light intensity, which are detrimental to the growth and development of lettuce. Supplemental lighting is an effective solution to this issue. This study aims to explore the influence of adding different wavelengths of red light to white LEDs for supplemental lighting on the growth and photosynthesis of lettuce leaves in solar greenhouses. Four experimental zones were established, namely white LED + 630 nm (T1), white LED + 660 nm (T2), white LED + 690 nm (T3), and no supplemental lighting (CK). The results indicate that supplemental lighting significantly increased the plant height, leaf area, biomass, and root indices. The chlorophyll content measurements showed higher photosynthetic pigment levels in the treated plants, enhancing the net photosynthesis rate (Pn). Thus, the combination of red and white light provides a more comprehensive spectrum and enhances the photosynthetic capacity of plant leaves. Simultaneously, under supplemental lighting, the plant fluorescence parameters Y(II), Fv/Fm, qP, and ETR were significantly elevated. It was found from the chlorophyll fluorescence frequency distribution graph that the leftward shift in Y(II) in the control group (CK) indicated that it was in a state of weak light stress, but supplemental lighting effectively ameliorated this stress environment. Among the types of supplemental lighting, the combination of white LEDs with 660 nm red light provides the most significant improvement in the growth and photosynthetic characteristics of lettuce under winter greenhouse conditions, and this combination holds great application potential in winter greenhouse lettuce production.

This study proposed a design method for forced-vibration subsoiling to reduce resistance and consumption. The vibration digging parameters of the Antlion larvae were obtained by high-speed camera, and a forced-vibration subsoiling shovel handle and six different shovel tips were designed by the non-smooth resistance-reducing surface design method. The resistance-reducing and consumption-reducing effects were verified in the field subsoiling experiment. The results showed that the resistance of subsoiling gradually decreased with the vibration frequency increasing. This vibration subsoiling method could not only reduce resistance but also reduce the total energy consumption, the resistance reduction rate reached 14.2–21.2%, and the total energy consumption was reduced by 11.2–16.5%. It could achieve the comprehensive subsoiling effect and create the soil conditions with the combination of loose and firmness. The non-smooth surface contributed to the reduction in resistance, and the forward speed had a more negligible effect on the resistance of subsoiling. The results had demonstrated that the combination of high-frequency vibration and non-smooth surfaces helped to reduce the cohesion of the soil, reduce the angle of internal friction in the soil, destroy the water film layer on the contact surface between the soil-touching components and the soil, change the soil flow state, and reduce the adhesion of the interface layer. The design method in this study could not only be applied to the design of vibration resistance reduction in the subsoiler but also had significance for the design of the other soil-contacting components.

Accurately obtaining roll angles is one of the key technologies to improve the positioning accuracy and operation quality of agricultural equipment. Given the demand for the acquisition of agricultural equipment roll angles, a roll angle monitoring model based on Kalman filtering and multi-source information fusion was established by using the MTi-300 AHRS inertial sensor (INS) and XW-GI 5630 BeiDou Navigation Satellite System (BDS), which were installed on agricultural equipment. Data of the INS and BDS were fused by MATLAB; then, Kalman filter was used to optimize the data, and the state equation and measurement equation of the integrated system were established. Then, an integrated monitoring terminal man–machine interactive interface was designed on MATLAB GUI, and a roll angle monitoring system based on the INS and BDS was designed and applied into field experiments. The mean absolute error of the integrated monitoring system based on multi-source information fusion during field experiments was 0.72°, which was smaller compared with the mean absolute errors of roll angle monitored by the INS and BDS independently (0.78° and 0.75°, respectively). Thus, the roll angle integrated model improves monitoring precision and underlies future research on navigation and independent operation of agricultural equipment.